JP2012088066A - Mobile system and map storage device with communication function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of redundancy in error detection in a technology for acquiring map data for map display from a center by communication.SOLUTION: When map area data to be downloaded and an error correction code are transmitted from a center, an HCI 12 in a map storage device 6 executes control so that the map area data and the error correction code are written in a map storage medium 8 through an RX buffer 13d and a switch circuit 13f. When receiving an instruction for reading out the downloaded map area data from the map storage medium 8 from a navigation apparatus, the HCI 12 executes control so that the map area data and the error correction code stored in the map storage medium 8 are inputted to an ECC circuit 13e through the switch circuit 13f and the RX buffer 13d. The ECC circuit 13e executes error correction of the inputted map area data by using the inputted error correction code and outputs the error-corrected map area data to the navigation apparatus.

Description

  The present invention relates to a mobile system and a map storage device with a communication function.

  2. Description of the Related Art Conventionally, a technique for acquiring map data for map display from a remote center by communication is known (see, for example, Patent Documents 1 to 3).

  In the above technique, when the center transmits map data, the map data is transmitted with an error detection code (for example, ECC, CRC, checksum) added, and the reception side receives the received error detection code. It is common to detect errors in map data. By doing so, it is possible to detect an error during communication.

  Further, when the map data is recorded on the storage medium, this time, in order to reduce the deterioration of the data at the time of recording, the error detection code is added again and recorded, and when the recorded map data is read, the map data is read. Generally, an error detection code is read together with data, and an error in map data is detected using the error detection code.

  As shown in FIG. 15, an error control circuit for detecting an error at the time of reception and an error control circuit for adding an error correction code at the time of recording and detecting an error at the time of reading are separately provided. It is common to have.

JP 2009-264875 A JP 2004-77254 A JP 2007-85768 A

  However, as described above, performing error detection separately at the time of communication and at the time of recording / reading is redundant as a system, increasing the processing load and increasing the number of error control circuits.

  The present invention has been made in view of the above points, and it is an object of the present invention to prevent redundant error detection in a technique for acquiring map data for map display from a remote center by communication.

  In order to achieve the above-mentioned object, the invention according to claim 1 communicates with the center (2) that transmits the map area data to be downloaded with the error detection code of the map area data to be downloaded added thereto. A map display device (3) for displaying a map and a map storage device (6) with a communication function, the map storage device (6) with a communication function comprising a map storage medium (8), a control Interface (11, 12), radio unit (13a, 13b, 7), error control circuit (13e), and radio unit (13a, 13b, 7) can be connected to the map storage medium (8) And a connection circuit (13c, 13d, 13f) capable of connecting the map storage medium (8) to the error control circuit (13e), and the wireless unit (13a, 13b, 7), Above The radio signal including the map area data to be downloaded and the error detection code transmitted by the computer (2), performing frequency conversion and demodulation on the received radio signal, and the control interface (11, 12) The data of the map area to be downloaded and the error detection code obtained as a result of frequency conversion and demodulation by the radio unit (13a, 13b, 7) are transmitted via the connection circuit (13c, 13d, 13f). And the control interface (11, 12) issues a read command to read the map area data to be downloaded from the map storage medium (8). Based on the reception from the display device (3), the map storage medium (8) stores the The map area data to be downloaded and the error detection code are controlled to be input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f), and the error control circuit (13e) When the data of the map area to be downloaded and the error detection code are input from the map storage medium (8) via the connection circuit (13c, 13d, 13f), the download target using the error detection code The map area data is detected in error, and the error-detected map area data without error is input to the control interface (11, 12). The control interface (11, 12) The data of the map area to be downloaded after the detected error is output to the map display device (3). This is a mobile system.

  Thus, the map area data and the error detection code received from the center (2) are recorded in the map storage medium (8) without going through the error detection process, and the map display device (3) uses the map area data. When the data is used, errors in the map area and the error detection code are input to the error control circuit (13e) to detect errors. Since detections can be combined into one, error detection redundancy can be prevented. Also in this way, it is possible to detect data errors at the time of reception and data errors at the time of recording and reading.

  According to a second aspect of the present invention, in the mobile system according to the first aspect, the control interface (11, 12) stores from the map display device (3) the data of the map area to be acquired is not specified. A map adjacent to the map area including the data of the map area including any section in the predetermined route based on the reception of the start request or the position of the map storage device with communication function (6) The area data is the map area to be downloaded.

  As described above, the control interface (11, 12) of the map storage device with communication function (6) spontaneously selects the map area to be downloaded without receiving the designation of the map area data from the map display device (3). Can be identified. In this way, in the map display device (3), the load for specifying the map area to be downloaded is reduced, and map area data that is likely to be required later in map display is prefetched. can do.

  In the mobile system according to claim 1, the radio unit (13a, 13b, 7) receives the position of the radio base station wirelessly transmitted by the radio base station in the mobile system according to claim 1, When the control interface (11, 12) receives from the map display device (3) a store start request that does not specify the data of the map area to be acquired, the radio unit (13a, 13b, 7) The received map area data adjacent to the map area including the position of the wireless base station is used as the map area to be downloaded.

  As described above, the communication on the map storage device with communication function (6) side can identify the data of the map area that is highly likely to be required later in the map display, so the current on the map display device (3) side There is no need to use the position specifying function, and the load on the map display device (3) side is reduced accordingly.

According to a fourth aspect of the present invention, in the mobile system according to any one of the first to third aspects, the control interface (11, 12) acquires data of a specific map area by communication. When receiving a recording / transfer command for instructing to output to the map display device (3) while recording in the map storage medium (8), the specific map is transmitted via the radio unit (13a, 13b, 7). A data request signal including an area ID is transmitted to the center (2), the center (2) receives the data request signal, and the specific map area indicated by the ID included in the data request signal. When the data error detection code of the map area is added to the data and transmitted, the radio unit (13a, 13b, 7) transmits the data of the specific map area transmitted by the center (2). And a radio signal including the error detection code, frequency conversion and demodulation are performed on the received radio signal, and the control interface (11, 12) has a communication speed with the center (2) stored in the map memory. Compared with a predetermined writing speed to the medium (8), and the control interface (11, 12) determines that the wireless section (13a, 13b, 7) if the communication speed is lower than the writing speed as a result of comparison. Control is performed so that the data of the specific map area and the error detection code obtained as a result of frequency conversion and demodulation are written to the map storage medium (8) via the connection circuit (13c, 13d, 13f). And the data of the specific map area obtained as a result of frequency conversion and demodulation by the radio unit (13a, 13b, 7) and Control signal is input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f), and the control interface (11, 12) When the speed is higher than the writing speed, the data of the specific map area and the error detection code obtained as a result of frequency conversion and demodulation by the radio unit (13a, 13b, 7) are stored in the map storage medium (8). To the error control circuit (13e) via the connection circuit (13c, 13d, 13f) without being recorded, and the error control circuit (13e) is connected to the connection circuit (13c, 13d, 13f), when the data of the specific map area and the error detection code are input, the error detection code is used to input the data of the specific map area. Data is input to the control interface (11, 12) without error and the error is detected in the specific map area.
The control interface (11, 12) outputs the input data of the specific map area after error detection to the map display device (3), and the control interface (11, 12) When the communication speed is higher than the writing speed, after the data of the specific map area and the error detection code are input to the error control circuit (13e), the center (2) The ID of the specific map area is transmitted via the radio unit (13a, 13b, 7) so as to transmit the data as the data of the map area to be downloaded together with the error detection code of the data of the specific map area. Is transmitted to the center (2).

  Thus, when the control interface (11, 12) is instructed to communicate and acquire data of a specific map area from the map display device (3) and output it to the map display device (3), When the communication speed with (2) is lower than the writing speed to the map storage medium (8), that is, when there is a margin for writing, the received data of the specific map area and the error detection code are sent to the map storage medium ( 8) and output to the map display device (3), if the communication speed is higher than the writing speed, that is, if writing cannot catch up, give up writing to the map storage medium (8) Data of a specific map area and error detection code data can be received from the center (2) and recorded in the map storage medium (8).

  According to a fifth aspect of the present invention, in the mobile system according to any one of the first to fourth aspects, the map display device (3) is according to any one of the first to fourth aspects. The mobile system includes a work memory (31) and a calculation circuit (33), and is a navigation device that calculates a guidance route from the current location to the destination. The calculation circuit (33) is the control interface (11, 12). The work memory (31) has a larger capacity than the memory provided in the control interface (11, 12), and the arithmetic circuit (33) has the same current location and the same destination. If it is determined whether or not it is in one map area, and if it is determined that it is in the same one map area, the guide route is sent to the control interface (11, 12). Calculation was done and when it is determined that there is no one and the same map area, characterized in that the calculation of the guidance route using the arithmetic circuit (33) itself the work memory (31).

  In this way, by causing the control interface (11, 12) to perform the guidance route calculation, the processing load on the arithmetic circuit (33) is reduced. However, since the calculation speed and memory capacity of the control interface (11, 12) are inferior to the calculation speed of the calculation circuit (33) and the memory capacity of the work memory (31), route calculation over a plurality of map areas is performed. Doing so will take a lot of time. Therefore, as described above, when the destination and the current location are not in the same one map area, the calculation circuit (33) calculates the guidance route, so that the route calculation does not take too much time. .

  Further, as described in claim 6, the feature of the in-vehicle device according to claim 1 of the present application can be understood as the feature of the invention of the map storage device with a communication function.

In order to achieve the above object, the invention described in claim 1
In addition, the code | symbol in the bracket | parenthesis in the said and the claim shows the correspondence of the term described in the claim, and the concrete thing etc. which illustrate the said term described in embodiment mentioned later. .

1 is a configuration diagram of a communication system according to an embodiment of the present invention. It is a block diagram of the map storage apparatus 6 with a communication function. It is a figure which shows the structure of a packet. It is a figure which shows the structure of a management table. It is a flowchart of the process which a main CPU performs at the time of the data reception and recording of a map area. It is a flowchart of the process which API performs at the time of the data reception and recording of a map area. It is a flowchart of the process which HCI performs at the time of the data reception and recording of a map area. It is a flowchart of the process which main CPU performs at the time of calculation of a guidance path | route. It is a flowchart of the process which HCI12 performs at the time of recording of the data of a guidance path | route. It is a flowchart of the process which API performs in order to acquire data from the map storage apparatus 6 with a communication function. It is a flowchart of a communication necessity determination process. It is a flowchart of the process which HCI performs in order to send data to the navigation apparatus 3, acquiring data through communication. It is a flowchart of the process which HCI performs in order to send data to the navigation apparatus 3, acquiring data from the map storage medium 8, without communicating. 4 is a flowchart of processing executed by an API for erasing data in a map storage medium 8; It is a block diagram which shows the example of the conventional mobile system.

  Hereinafter, an embodiment of the present invention will be described. FIG. 1 shows a configuration of a communication system according to the present embodiment. This communication system includes an in-vehicle system 1 mounted on a vehicle, and a center 2 that is installed in a building in a remote place outside the vehicle and can communicate with the in-vehicle system 1. Communication between the in-vehicle system 1 and the center 2 is realized via a wide area network (for example, the Internet) to which the center 2 is connected and a wireless base station connected to the wide area network. Radio base stations are arranged at a plurality of locations, and each communicable range has a radius of about 5 kilometers centering on the radio base station. When the in-vehicle system 1 is within the communicable range of any one of these radio base stations, the in-vehicle system 1 wirelessly connects to the one radio base station and communicates with the center 2 via the radio base station and the wide area network. .

  The center 2 transmits map area data to the in-vehicle system 1 in communication with the in-vehicle system 1. The map area is each section when the geographic range is divided into a plurality of sections, and the map area data is map data of roads (links, nodes), facilities, and the like in the map area. In the present embodiment, it is assumed that the map area is a rectangular geographical section of 10 km long × 10 km wide.

  The center 2 includes, for example, a CPU, a RAM, a ROM, a large-capacity storage medium (for example, a magnetic storage medium, a flash memory, etc.), and a device provided with a communication interface for connecting to a wide area network. Data of each map area is recorded, and the CPU reads the data of the map area recorded on the large-capacity storage medium based on receiving the data request signal of the map data via the communication interface, and performs communication. The map area data and the like are transmitted to the in-vehicle system 1 using the interface.

  The in-vehicle system 1 includes a navigation device 3 (corresponding to an example of a map display device), a display device 4, a radio tuner 5, a map storage device 6 with a communication function, and an RF circuit 7. The display device 4 is a device that displays an image to the user according to the control of the navigation device 3. The radio tuner 5 is a device that receives a radio broadcast according to the control of the navigation device 3 and outputs a sound of the radio broadcast to a speaker (not shown).

  The navigation device 3 is a device that calculates a guidance route from the current location to the destination and guides movement along the calculated guidance route. The navigation device 3 includes a ROM 30, a work memory (for example, RAM) 31, a position detection unit 32, a main CPU ( (Arithmetic circuit) 33 is provided. The position detection unit 32 includes various sensors for specifying the current position of the in-vehicle system 1 such as a GPS receiver, a gyro sensor, and a vehicle speed sensor. The main CPU 33 executes various programs recorded in the ROM 30 to realize various processes described later using the work memory 31.

  The map storage device 6 with a communication function is a device for receiving and recording map area data and the like for use by the navigation device 3 from the center 2. In FIG. 2, the structure of the map preservation | save apparatus 6 with a communication function is shown. The map storage device 6 with a communication function includes an RF circuit 7, a map storage medium 8, and a control unit 9. The control unit 9 includes an API 11, an HCI 12, and a baseband unit 13. The baseband unit 13 includes a modulation unit 13a, a demodulation unit 13b, a TX buffer 13c, an RX buffer 13d, an ECC circuit 13e, and a switch circuit 13f. have.

  An API (Application Interface) 11 is an interface device that exchanges signals with the main CPU 33 of the navigation device 3. For example, an API (Application Interface) 11 may be realized by a microcontroller including a CPU, work memory (RAM), ROM, and I / O. Good. Hereinafter, various processes executed by the API 11 are realized by the CPU of the API 11 reading a predetermined program from the ROM and executing it using the work memory.

  The HCI (Host Control Interface) 12 controls the baseband unit 13 and the map storage medium 8 according to the content of the signal received from the API 11, thereby communicating with the center 2 and writing data to the map storage medium 8 and the map. This is an interface device that controls reading of data from the storage medium 8, and may be realized by, for example, a microcontroller including a CPU, a work memory (RAM), a ROM, and an I / O. Hereinafter, various processes executed by the HCI 12 are realized by the CPU of the HCI 12 reading a predetermined program from the ROM and executing it using the work memory.

  The map storage medium 8 is a large-capacity storage medium (for example, flash memory) for recording map area data and the like, and receives control signals such as address designation, chip select (CS), read (RD), and write (WE). The control terminal for receiving is connected to the HCI 12, and the data terminal (DATA) for inputting / outputting data is connected to the switch circuit 13f.

  The RF circuit 7 performs frequency conversion, amplification and the like on the signal output from the modulation unit 13a, and transmits the resultant signal as a radio signal using an antenna. Further, the RF circuit 7 performs frequency conversion, amplification, etc. on the radio signal received from the antenna, and inputs the resulting signal to the demodulation unit 13b.

  The modulation unit 13 a modulates the data input from the TX buffer 13 c and inputs a signal obtained as a result to the RF circuit 7. The demodulator 13b demodulates the signal input from the RF circuit 7, and inputs the resulting data to the ECC circuit 13e via the RX buffer 13d.

  The TX buffer 13c temporarily holds the data input from the ECC circuit 13e, and then sequentially inputs the data to the modulation unit 13a. The RX buffer 13d temporarily holds the data input from the demodulation unit 13b, and then inputs the held data to the ECC circuit 13e according to control from the HCI 12.

  The ECC circuit 13e adds an error correction code to the transmission packet received from the HCI 12, and inputs the data of the transmission packet obtained as a result to the TX buffer 13c. The ECC circuit 13e receives the data input from the RX buffer 13d, and corrects the error of the packet using an error correction code included in the packet that the received data constitutes. Error correction is a process of detecting an error in data in a packet and correcting the detected error. Packets for which no error was found even after error detection (that is, packets that had no error after error detection), and packets that were found to be error-detected and were corrected by error correction (that is, error detection) The error-free packet) is output to the HCI 12, but an error is detected by error detection, but the error is not corrected by error correction (ie, an error-detected packet that has undergone error detection) is It may or may not be output to the HCI 12.

  With this configuration, when the HCI 12 inputs a transmission packet to the ECC circuit 13e in the map storage device 6 with a communication function, the ECC circuit 13e adds an error correction code to the transmission packet and adds a TX buffer 13c. The TX buffer 13c temporarily holds the transmission packet data input from the ECC circuit 13e and then inputs the data to the modulation unit 13a. The modulation unit 13a modulates the data input from the TX buffer 13c. The RF circuit 7 performs frequency conversion on the signal input from the modulation unit 13a and transmits it as a radio signal.

  Further, the RF circuit 7 performs frequency conversion on the received radio signal, and inputs the resulting signal to the demodulator 13b. The demodulator 13b demodulates the signal input from the RF circuit 7, and the result Data is input to the RX buffer 13d. The RX buffer 13d temporarily holds the data input from the demodulator 13b and then inputs the data to the ECC circuit 13e. The ECC circuit 13e receives the data input from the RX buffer 13d. Error correction of the packet is performed using an error correction code included in the packet to be configured, and an errored packet after error detection is output to the HCI 12. In this way, the map storage device 6 with a communication function can communicate with an external device (for example, the center 2).

  The switch circuit 13f is a circuit capable of switching between a state in which the TX buffer 13c and the data terminal of the map storage medium 8 are connected and a state in which the RX buffer 13d and the data terminal of the map storage medium 8 are connected. Switching is realized by control.

  The main CPU 33 of the navigation device 3 has a higher calculation speed than the API 11 and the HCI 12, and the work memory 31 has a larger capacity than the work memory (RAM) provided in the API 11 and the HCI 12.

  Here, before describing the operation of such a communication system, a packet transmitted and received between the map storage device 6 with a communication function and the center 2 will be described. A packet is a data transmission unit. As illustrated in FIG. 3, the map area data or the like is divided into a plurality of pieces, and one packet is generated for each divided data. One packet includes a packet ID unique to the packet, a data ID unique to the data before division (corresponding to an area ID when the data before division is map area data), and one of the divided data A plurality of packets are generated by adding an error correction code (ECC) for correcting an error of the divided data and a CRC (a kind of error detection code) of the packet. In addition, the data of each map area of this embodiment is comprised by the same packet number.

  A management table for managing the contents of data recorded in the map storage medium 8 will be described. As shown in FIG. 4, the management table has one record (corresponding to one line of data in FIG. 4) for each data (mainly map area data, otherwise guidance route data) recorded in the map storage medium 8. Is provided).

  A record corresponding to data of a certain map area includes an area ID of the map area, a storage address of the data of the map area in the map storage medium 8, a priority of the data of the map area, a map of the data of the map area It includes data of the update date and time (date and time last received from the center 2 and recorded) in the storage medium 8.

  In addition, a record corresponding to data of a certain guidance route includes a guidance route ID indicating that the data is guidance route data, a storage address of the guidance route data in the map storage medium 8, and priority of the guidance route data. The update date and time (date and time last written in the map storage medium 8) of the guidance route data is included. This management table is recorded in the map storage medium 8.

  The guidance route data is a list of roads and intersections from the current location to the destination. The area ID of the map area to be read is assigned to the intersection information. A necessary map area can also be specified based on the area ID recorded in this way.

  The correspondence relationship between the area ID of the map area and the geographic area covered by the map area is determined in advance, and the correspondence table is recorded in the ROM of the main CPU 33, API 11, and HCI 12. The main CPU 33, API 11, and HCI 12 can refer to this correspondence.

  Hereinafter, the operation of such a communication system will be described.

[Reception and storage of map area data]
First, a process of receiving map area data and the like from the center 2 and storing it in the map storage medium 8 will be described. While the navigation device 3 is operating, the main CPU 33 repeatedly executes a process as shown in FIG. 5 by executing a predetermined program.

  In this process, the main CPU 33 repeatedly determines in step 105 whether or not a new trigger condition is satisfied until it is satisfied. That is, it waits until a new trigger condition is satisfied.

Any trigger condition may be used. For example, the following is used.
(1) A predetermined time (for example, 10 minutes) has elapsed since the last trigger condition was satisfied.
(2) The necessity to read out data in the map area has occurred.
(3) Reading the guidance route data.
The above condition (2) is that, for example, when a map centered on the current position is displayed on the display device 4, the map displayed on the display device 4 is scrolled as a result of the movement of the vehicle, and the current display is performed. This is established when it is necessary to display an area different from the map area.

  If it is determined in step 105 that the trigger condition is satisfied, then in step 110, whether or not communication with the center 2 is possible (wireless connection with any one of the radio base stations) is repeatedly determined until communication is possible. When communication is possible, in step 115, a store start request is output to the API. This store start request does not include data specifying a specific map area. That is, this store start request is a store start request that does not specify data of the map area to be recorded. After outputting the store start request, the process returns to step 105, and it is repeatedly determined whether or not the next trigger condition is satisfied until it is satisfied.

  Receiving the store start request output from the main CPU 33, the API 11 starts executing the process shown in FIG. 6 and determines whether or not the guidance route data to the destination is set in step 120. Whether or not the guidance route data is set is based on whether or not the guidance route data is recorded in the map storage medium 8, that is, whether or not a record having the guidance route ID is included in the management table. Judgment based on.

  Similar to the map area data described later, the HCI 12 can read out data recorded in the map storage medium 8 such as a management table via the RX buffer 13d and the ECC circuit 13e, and the API 11 stores the management table in the HCI 12. , It is possible to acquire data recorded in the map storage medium 8 such as a management table from the HCI 12.

  If it is determined that the guidance route data is set, in step 125, the guidance route data recorded in the map storage medium 8 is read out based on the storage address of the guidance route data in the management table. The area ID of the map area including any section in the guide route set in the route data is specified, a list of area IDs of the specified map area is created, and the list is recorded in the RAM as an area list.

  If it is determined that it is not recorded in step 120, it is determined in step 130 whether or not the area ID of the latest read area which is the map area read last is recorded in the API 11 RAM. If it is determined, a list of map areas adjacent to the latest read area is created and used as an area list.

  When the API 11 reads a map area from the map storage medium 8, the area ID of the read map area is recorded in the RAM as the map area read last. Therefore, in many cases, the area ID of the latest read area is recorded in the RAM of the API 11. However, it may be determined that the latest read area is not recorded in the API immediately after the power is turned on, for example, because it is not recorded in step 130.

  If it is determined that it is not recorded in step 130, then in step 140, the radio base station position is set with respect to the radio base station currently wirelessly connected by radio communication using the RF circuit 7 and the baseband unit 13. It is determined whether or not the position of the wireless base station transmitted by the wireless base station as a response to the inquiry can be received via the RF circuit 7 and the baseband unit 13. If it is determined that it has been received, in step 145, a list of area IDs of the map areas adjacent to the map area including the position of the base station is created and used as an area list.

  This is realized when the communication between the base station and the in-vehicle system 1 is within a distance (communication distance) within 5 km, and the vertical and horizontal length of one map area is about 10 km. This is because it is longer than the communicable distance. That is, since there is a high possibility that the base station and the in-vehicle system 1 are in the same map area, acquiring the data of the map area adjacent to the map area including the base station position is a function of the map storage device 6 with a communication function. This is almost the same as acquiring data of a map area adjacent to the map area including the position.

  As described above, the communication on the map storage device 6 with communication function side can identify the data of the map area that is highly likely to be required later in the map display, so the current position detection unit 32 on the navigation device 3 side There is no need to use the position specifying function, and the load on the navigation device 3 side is reduced accordingly.

  If it is determined in step 140 that the signal could not be received, the process proceeds to step 170. After the area list is created in steps 125, 135, and 145, in step 150, the area list is compared with the management table, and the map area included in the area list is included in the management table. It is determined whether there is a shortage map area that is not a map area (that is, a map area that is not stored in the map storage medium 8), and if it is determined that there is no shortage map area, the process proceeds to step 170.

  If it is determined in step 150 that there is a shortage map area, then in step 155, it is determined whether or not the free space of the storage medium is greater than the necessary capacity necessary for recording the data in the shortage map area. The capacity necessary for recording data of a certain map area is a predetermined value determined in advance. If it is determined that the required capacity is exceeded, the shortage map area is set as the reception area in step 160 as it is, and if it is determined that the required capacity is not exceeded, the next store condition for setting the write mode to the overwrite mode is set in HCI 12 in step 165. After setting, the lack map area in step 160 is set as the reception area. In step 170, “null (may be empty data)” indicating that there is no map area to be read is set in the reception area.

  Subsequent to steps 160 and 170, in step 175, the processing code indicating the start of storage, the area ID of the reception area, and the storage method indicating whether overwriting or appending to an empty storage area are output to the HCI 12. . Note that the default value of the saving method to be output is appending, and the saving method is overwritten only when the saving method is set to overwrite in step 165. After step 175, the process of FIG. 6 ends.

  Further, during operation, the HCI 12 always executes the processing shown in FIG. 7 and waits until the store start processing code, the reception area ID, and the storage method are received from the API 11 in step 205. Note that the number of area IDs in the reception area may be one, plural, or empty (null). If it is empty, the received store start processing code is discarded, and in step 205, the receipt of the store start processing code is awaited again.

  When the number of area IDs of the reception area received together with the store start processing code is 1 or more, the process proceeds to step 210 to control the switch circuit 13f to connect the RX buffer 13d to the data terminal of the map storage medium 8. . At this time, the modulator 13a and the demodulator 13b are kept operating.

  Subsequent to step 210, the processing of steps 215 to 275 is executed once for each of the data of one or more map areas indicated by the received area ID of the reception area. Below, the process of steps 215-275 about one map area (henceforth a target area) is demonstrated.

  First, in step 215, it is determined whether the recording method is overwriting or additional writing according to the storage method acquired in step 205.

  If it is determined that the data is overwritten, the process proceeds to step 225 to start communication, and a transmission packet including the area ID of the target map area is input to the ECC circuit 13e. As a result, a transmission packet signal (corresponding to a data request signal) including the area ID of the target map area is transmitted to the center 2 via the ECC circuit 13e, the TX buffer 13c, the modulation unit 13a, and the RF circuit 7. The

  Then, the CPU of the center 2 receives the data request signal via the communication interface by executing a predetermined program in the ROM, reads the area ID in the packet included in the data request signal, and stores the area ID in this area ID. The corresponding target map area data is read from the large-capacity storage medium, the read target map area data is divided into a plurality of packets, and for each divided packet, the packet ID, the target map area area ID, the target map area Further including data ECC (Error Correction Code) and CRC (see FIG. 3), the radio signals of the plurality of packets are sequentially transmitted to the in-vehicle system 1, and the radio signals sequentially reach the map storage device 6 with a communication function. .

  The packet that reaches the map storage device 6 with the communication function is subjected to frequency conversion or the like by the RF circuit 7 and demodulated by the demodulator 13b. As a result, the RX buffer 13d has the capacity of the RX buffer 13d (for example, 32 bits). It accumulates sequentially.

  On the other hand, the HCI 12 that has transmitted the data request signal determines an address to which data in the target map area in the map storage medium 8 is to be written in the following step 230. If there is an area in which no data is recorded in the map storage medium 8, the address to be determined is one of the areas (for example, the start address of the area), and an area in which no data is recorded in the map storage medium 8 If it does not already exist, it may be one of the areas where the data of the map area with the oldest update date is recorded (for example, the start address of the area) in the management table, or the data of the map area with the lowest priority is stored. One of the recorded areas may be used.

  In subsequent step 235, whether or not the RX buffer 13d is in the full storage state by the packet of the data of the target map area received from the center 2 is repeated until it is determined that the RX is in the full storage state. The RX buffer 13d being in the full storage state means that the data input from the demodulation unit 13b (or the map storage medium 8) is stored in all the predetermined storage areas in the RX buffer 13d.

  Whether or not the RX buffer 13d is in the full storage state is determined based on a notification signal from the RX buffer 13d. The RX buffer 13d sequentially stores the received data from the first bit storage area, and outputs a notification signal when the value of the last bit storage area changes. If it is determined that the full storage state is reached, then in step 240, a write command and a write address designation are output to the map storage medium 8. The write address designation value is the write address determined in the previous step 230.

  At this time, since the RX buffer 13d and the map storage medium 8 are connected, all the data input and held in the RX buffer 13d from the demodulator 13b by this write command and write address designation output The data is recorded in the map storage medium 8 in order from the write address, and the contents of the RX buffer 13d are cleared to empty.

  Subsequently, in step 245, it is determined whether or not all the data of the target map area has been recorded in the map storage medium 8, and whether or not the last packet of the data of the target map area has been recorded in the map storage medium 8 is recorded. If it is determined that it is not, the process returns to step 230. In this way, the write address is determined until all data in the target map area is recorded (step 230), waits until the RX buffer 13d is in the full storage state (step 235), and when the full storage state is reached, the RX The process of recording the contents of the buffer 13d in the map storage medium 8 (step 240) is repeated.

  Note that the write address of step 230 in this repetition is shifted by the size of the RX buffer 13d each time it is executed. In this way, map area data can be sequentially written to the RX buffer 13d.

  If it is determined in step 245 that all data of the target map area has been recorded in the map storage medium 8, then in step 250, the switch circuit 13f is controlled to connect the TX buffer 13c to the map storage medium 8, In order to inhibit wireless transmission and save power consumption, the operation of the modulation unit 13a is stopped.

  Subsequently, in step 255, a record to be added to the management table is input to the TX buffer 13c via the ECC circuit 13e, as in the case of data transmission. This record includes the area ID of the target map area, the data write address (start address) of the target map area, the priority having a value of zero, and the update date and time (that is, the current date and time).

  Subsequently, in step 260, a write address of the record in the map storage medium 8 is determined. The storage area of the management table in the map storage medium 8 is determined in advance, and the write address determined here is the address of an area that is not currently used in the storage area of the management table.

  In the following step 265, whether or not the TX buffer 13c is in the full storage state is repeated until it is determined that the TX buffer 13c is in the full storage state. The TX buffer 13c being in the full storage state means that the data input from the ECC circuit 13e is stored in all the predetermined storage areas in the TX buffer 13c. Whether the full storage state has been reached is determined based on a notification signal from the TX buffer 13c (output in the same procedure as the RX buffer 13d). If it is determined that the full storage state is reached, then in step 270, the write command and write address designation are output to the map storage medium 8. The write address designation value is the write address determined in the immediately preceding step 260.

  Since the TX buffer 13c and the map storage medium 8 are connected, all data held in the TX buffer 13c are recorded in the map storage medium 8 in order from the write address by this write command and write address designation output. The contents of the TX buffer 13c are cleared to empty.

  Subsequently, in step 275, it is determined whether or not the management table is recorded in the map storage medium 8. If it is determined that the management table is not recorded, the process returns to step 260. Thus, the write address is determined until the management table is recorded (step 260), and the TX buffer 13c is waited until the full storage state is reached (step 265), and the contents of the TX buffer 13c are reached when the full storage state is reached. Is recorded in the map storage medium 8 (step 270). Note that the write address of step 260 in this repetition is shifted by the size of the TX buffer 13c each time it is executed.

  If it is determined in step 275 that a new record of the management table has been recorded in the map storage medium 8, the process for the current target map area is terminated, and if there is a map area that has not yet been recorded, that is determined as the target map area. Return to step 215.

  If it is determined in step 215 that the data is additionally written, then in step 220, the free space of the map storage medium 8 is made redundant by adding the capacity of the target map area (packet ID, data ID, ECC, CRC). If it is determined that the data is smaller, the data of the target map area can be additionally recorded without any problem, and the process proceeds to step 225. Note that in step 230 when it is determined that additional writing is to be performed, the write address is always determined as the address of the free area.

  If it is determined in step 220 that the free space of the map storage medium 8 is smaller than the capacity of the target map area, the process proceeds to step 280 to notify the API 11 that writing has failed due to insufficient free space in the map storage medium 8. Thereafter, the HCL store process is returned to step 205. When the API 11 receives this notification, the API 11 outputs it to the main CPU 33 as it is. Upon receiving this notification, the main CPU 33 causes the display device 4 to display a writing failure.

  After the map area data of all area IDs received in step 205 is recorded in the map storage medium 8, a completion code indicating completion of writing is output to the API 11, and then the HCL store process is returned to step 205. The API 11 that has received the completion code outputs it to the main CPU 33 as it is.

  As described above, when the API 11 of the map storage device 6 with a communication function receives a store start request from the navigation device 3, the API 11 can spontaneously specify the map area to be downloaded without specifying the data of the map area. it can. In this way, the map display device 3 reduces the load for specifying the map area to be downloaded, and pre-fetches the map area data that is likely to be required later in the map display. Can do.

  In addition, by automatically acquiring the data in the adjacent area, the data can be pre-read even if there is an abnormality in the communication in the adjacent area, and the operation can be continued even if the communication navigation cannot be operated. it can.

  In the above description, when the API 11 receives a store start request from the main CPU 33, the API 11 immediately executes the processing of FIG. 6. However, the main CPU 33 adds a storage execution start condition (for example, 1) to the store start request. The API 11 may start the processing of FIG. 6 when the storage execution start condition is satisfied, including information on the time after the next map data is read. In other words, the reception of the map area data and the start of the recording can be notified in advance from the main CPU 33 to the API 11 so that the immediately preceding store start request is not required.

[Calculation of guidance route data, etc.]
Next, guidance route data calculation processing executed by the main CPU 33 will be described. When the user inputs a destination to an operation device (button, touch panel, etc.) (not shown) of the navigation device 3, the main CPU 33 calculates a guidance route from the current location detected by the position detection unit 32 to the destination. The execution of the process shown in FIG. 8 is started.

  First, in step 305, a map area necessary for calculation of the guidance route is specified based on the positions of the current location and the destination, and whether or not data of all specified map areas is stored in the map storage medium 8 is determined. This is determined by referring to the management table. The map area necessary for calculating the guidance route is, for example, a straight line having both the starting point and the destination as both ends, and the shortest distance from the straight line is 1/5 of the length of the straight line. An area is calculated, and all map areas that include such an area are set as map areas necessary for calculation of the guidance route.

  If it is determined that some of the map area data necessary for the calculation of the guide route is not stored in the map storage medium 8, the process proceeds to step 310, and the center 2 is transmitted to the center 2 using the map storage device with communication function. To send a route calculation request including the destination and current location. Upon receiving this route calculation request, the center 2 calculates a guide route from the current location to the destination included in the route calculation request recorded in the center 2, and transmits the calculated guide route data to the in-vehicle system 1. Then, in step 315, the main CPU 33 receives the guidance route data via the map storage device 6 with a communication function.

  If it is determined in step 305 that all the map area data necessary for the calculation of the guidance route is recorded in the map storage medium 8, then in step 320, the destination and current location are in the same map area. Is determined based on the above correspondence table.

  If it is determined that they are within the same one map area, then in step 325, in order to cause the API 11 to calculate the guidance route, a route calculation command including the current location and the position of the destination is output to the API 11. Upon receiving this route calculation command, the API 11 reads the map area data including the current location and the destination in the map storage medium 8 through the switch circuit 13f, the RX buffer 13d, and the HCI 12 based on the received current location and destination. Then, the guide route from the current location to the destination is calculated, and the calculated guide route is output to the main CPU 33, and the main CPU 33 acquires it. The details of the method for reading the map area data from the map storage medium 8 will be described later.

  In this way, the processing load on the main CPU 33 is reduced by causing the API 11 to perform the guidance route calculation. However, since the calculation speed and work memory capacity of the API 11 are inferior to those of the main CPU 33, it takes an enormous amount of time to calculate a route over a plurality of map areas.

  Therefore, if the destination and the current location are not within the same one map area in step 320, then in step 330, the main CPU 33 reads the necessary map area data from the map storage medium 8, and based on the read data. To calculate the guidance route. Thereby, it is possible to prevent the route calculation from taking too much time. Details of the method of reading the map area data from the map storage medium 8 will be described later.

  After obtaining the guidance route in steps 315, 325, and 330, in step 335, in order to record the guidance route data in the map storage medium 8, a guidance route store request is output to the API 11. This guide route store request includes a storage method indicating whether overwriting or appending to a free storage area. When step 315 or 330 is executed, guidance route data is also included in the guidance route store request. As a storage method, overwriting may be designated or additional writing may be designated. If overwriting is specified, it is possible to avoid the problem that the entire path data may not be recorded.

  When the API 11 receives this guide route store request, if it has calculated the guide route itself, it includes the guide route in the guide route store request and inputs it to the HCI 12. If it has not calculated the guide route itself, the API 11 stores the guide route store request. Is input to the HCI 12 as it is.

  When the HCI 12 receives the input guidance route store request, the HCI 12 starts executing the route store processing shown in FIG. 9. First, in step 410, the HCI 12 controls the switch circuit 13 f to connect the TX buffer 13 c to the map storage medium 8. In addition, in order to inhibit wireless transmission and save power consumption, the operation of the modulation unit 13a is stopped. The demodulator 13b is kept operating.

  Subsequently, in step 415, it is determined whether the recording method is overwriting or additional writing according to the storage method in the received guide route store request. If it is determined that the data is overwritten, in the subsequent step 425, the data of the guide route in the received guide route store request is input to the TX buffer 13c via the ECC circuit 13e by the same method as the wireless transmission. Specifically, the data of the guidance route is divided into a plurality of packets, and each divided packet further includes a packet ID, an ID indicating a guidance route, and a CRC, and sequentially outputs them to the ECC circuit 13e. Then, the ECC circuit 13e creates an ECC (error correction code) of the data (division data of the guidance path data) received from the HCI 12, further includes the created ECC in the packet, and sequentially inputs it to the TX buffer 13c. I will do it.

  In subsequent step 430, the address of the writing destination of the map storage medium 8 is determined. If there is an area in which no data is recorded in the map storage medium 8, the address to be determined is one of the areas (for example, the start address of the area), and an area in which no data is recorded in the map storage medium 8 If it is not already present, it may be one of the areas where the oldest data is recorded (the area with the oldest writing date) (for example, the start address of that area).

  In the subsequent step 435, it is repeated until it is determined that the TX buffer 13c is in the full storage state based on the packet of the guidance route data output from the ECC circuit 13e until it is determined that the full storage state is reached. Whether the full storage state has been reached is determined based on a notification signal from the TX buffer 13c. The TX buffer 13c sequentially stores the received data from the first bit storage area, and outputs a notification signal when the value of the last bit storage area changes.

  If it is determined that the full storage state is reached, then in step 440, a write command and a write address designation are output to the map storage medium 8. The write address designation value is the write address determined in the immediately preceding step 430.

  At this point, since the TX buffer 13c and the map storage medium 8 are connected, all data held in the TX buffer 13c is sequentially transferred from the write address to the map storage medium 8 by the output of the write command and the write address designation. It is recorded, and the contents of the TX buffer 13c are cleared to empty.

  Subsequently, in step 445, it is determined whether or not all the data of the guide route has been recorded in the map storage medium 8, and if it is determined that it has not been recorded, the process returns to step 430. As described above, the write address is determined until all the data of the guide route is recorded (step 430), and the TX buffer 13c is waited until the full storage state is reached (step 435). The process of recording the contents of 13c in the map storage medium 8 (step 440) is repeated. Note that the write address in step 430 in this repetition is shifted by the size of the TX buffer 13c each time it is executed.

  If it is determined in step 445 that all the data of the guide route has been recorded in the map storage medium 8, then in step 455, the data is added to the management table via the ECC circuit 13e in the TX buffer 13c as in the case of data transmission. The record of the guide route for inputting is input. This field includes a guidance route ID indicating that the data is guidance route data, a storage address (leading address) of the guidance route data in the map storage medium 8, and a priority (maximum value) of the guidance route data. The update date (current date) of the guidance route data is included.

  Subsequently, in step 460, the write address of the record in the map storage medium 8 is determined in the same manner as in step 260. In subsequent step 465, it is repeated until it is determined that the TX buffer 13c is in a full storage state or not. Whether the full storage state has been reached is determined based on a notification signal from the TX buffer 13c.

  If it is determined that the full storage state is reached, then in step 470, the write command and write address designation are input to the map storage medium 8, and the write address designation value is the write address determined in the immediately preceding step 460.

  Since the TX buffer 13c and the map storage medium 8 are connected at this time, all the data held in the TX buffer 13c is recorded in the map storage medium 8 in order from the write address by the output of the write command and the write address designation. In addition, the contents of the TX buffer 13c are cleared to empty.

  Subsequently, in step 475, it is determined whether or not all the data of the record to be added to the management table has been recorded in the map storage medium 8. If it is determined that it has not been recorded, the process returns to step 460. In this way, the write address is determined until the management table is recorded (step 460), waits until the TX buffer 13c is in the full storage state (step 465), and the contents of the TX buffer 13c when the full storage state is reached. Is repeatedly recorded in the map storage medium 8 (step 470), whereby the guidance route data (and accompanying data) is recorded in the map storage medium 8. Note that the write address in step 460 in this repetition is shifted by the size of the TX buffer 13c each time it is executed.

  If it is determined in step 415 that the data is to be added, then in step 420, the free capacity of the map storage medium 8 is the capacity of the guidance route data (capacity in units of packets after being made redundant and given ECC). ), And if it is not smaller, the guidance route data can be additionally recorded without any problem. In step 430 in the case where it is determined that writing is an additional writing, the write address is always determined as the address of the free area. If it is determined in step 420 that the size is small, the process proceeds to step 480 where the API 11 is notified that the map storage medium 8 has insufficient free space and the writing has failed, and then the processing in FIG. When the API 11 receives this notification, the API 11 outputs it to the main CPU 33 as it is. Upon receiving this notification, the main CPU 33 causes the display device 4 to display a writing failure. If it is determined in step 475 that the management table has been recorded in the map storage medium 8, a completion code indicating completion of writing is output to the API 11, and the processing in FIG. The API 11 that has received the completion code outputs it to the main CPU 33 as it is.

  By doing so, the guidance route data calculated by the main CPU 33 or the API 11 as needed is recorded in the map storage medium 8.

[Process of obtaining map data from the map storage device 6 with communication function]
Next, various processes for the main CPU 33 to acquire map data from the map storage device 6 with a communication function will be described. The main CPU 33 needs to acquire the data of the specific map area for the purpose of calculating the guidance route, displaying the map image of the specific map area on the display device 4, and the like, and the navigation device 3 is the center 2 If it is in a position where communication is possible (for example, it is determined by trying communication with the center 2), a data request is input to the API 11. This data request includes the area ID of the specific map area and information indicating that communication with the current center 2 is possible.

  Upon receiving such a data request, the API 11 executes an acquisition process as shown in FIG. First, in step 510, a communication necessity determination is performed which is a determination as to whether or not the specific map data needs to be acquired by communication.

  FIG. 11 shows details of this communication necessity determination. In the following, the data of the specific map area where the necessity of acquisition has occurred (hereinafter also referred to as necessary data) is referred to as necessary data. First, in step 511, it is determined based on the management table whether or not necessary data is stored in the map storage medium 8. If it is determined that it has not been saved, it is determined in step 512 that communication is necessary.

  If it is determined that it is stored, the process proceeds to step 513, where the update date / time of the necessary data in the map storage medium 8 is specified based on the management table, and whether the period from the current date / time to the update date / time is smaller than a predetermined threshold TH If it is determined that the necessary data in the map storage medium 8 is old, the process proceeds to step 512, where it is determined that communication is necessary. If it is determined that the data is small (required data in the map storage medium 8 is relatively new), the process proceeds to step 515 and the priority of the necessary data in the management table is increased by 1, and then communication is unnecessary in step 517. Is determined. The reason why the priority is increased by 1 is to increase the priority of the data as the number of times the data of the map area is read from the map storage medium 8 increases. After step 512 or 517, the communication necessity determination ends.

  After step 510 in FIG. 10, the process proceeds to step 520, where it is determined whether or not to perform communication according to the result of the communication necessity determination. The process for recording the necessary data to be acquired in the map storage medium 8 is executed. If it is determined not to be performed, the process proceeds to step 530 to execute processing for reading necessary data from the map storage medium 8 without performing communication.

  Specifically, in step 525, a record instructing the HCI 12 to output data to the navigation device 3 while acquiring and recording the data of a specific map area, which is necessary data, in the map storage medium 8.・ Outputs transfer instructions. This recording / transfer command includes the area ID of the map area, which is necessary data, and a storage method indicating overwriting.

  When receiving the acquisition / recording command, the HCI 12 starts the processing shown in FIG. First, in step 610, the switch circuit 13f is controlled to connect the RX buffer 13d to the map storage medium 8. At this time, the modulator 13a and the demodulator 13b are kept operating.

  Subsequently, in step 620, communication is started, and a data request signal including the area ID of the map area, which is necessary data, is sent to the center 2 via the ECC circuit 13e, the TX buffer 13c, the modulation unit 13a, and the RF circuit 7. Send.

  Then, the CPU of the center 2 receives the data request signal by executing a predetermined program in the ROM, reads out the data of the map area indicated by the area ID included in the data request signal from the mass storage medium, The read target map area data is divided into a plurality of packets, and each divided packet further includes a packet ID, an area ID, an ECC (error correction code), and a CRC as shown in FIG. The packet group sequentially reaches the map storage device 6 with a communication function.

  On the other hand, the HCI 12 that has transmitted the data request signal has a communication speed with the center 2 (that is, a bit rate of data received from the center 2) as a writing speed from the RX buffer 13d to the map storage medium 8 (step 625). It is determined whether it is smaller than (predetermined as a constant). If it is determined that the communication speed is lower than the writing speed (there is a margin for writing), the process proceeds to step 630.

  In step 630, as in step 230 of FIG. 9, the address of the write destination of the map storage medium 8 is determined. Further, in step 635, whether or not the RX buffer 13d is in the full storage state by the packet of the map area data received from the center 2 is repeated until it is determined that the RX is in the full storage state. If it is determined that the full storage state has been reached, then in step 640, the write command and write address designation are output to the map storage medium 8, and the data in the RX buffer 13d is acquired in the work memory of the HCI 12 via the ECC circuit 13e. To do. The write address designation value is the write address determined in the immediately preceding step 630. The HCI 12 outputs the map area data acquired in the work memory of the HCI 12 to the main CPU 33 via the API 11. Thereby, the main CPU 33 can acquire the data of the map area.

  In this way, all the data held in the RX buffer 13d is recorded in the map storage medium 8 in order from the write address, and all the data held in the RX buffer 13d is output to the ECC circuit 13e. In 13e, error correction is performed as necessary based on the ECC (error correction code) in the data, and the resulting map area data is input to the HCI 12. Thereafter, the contents of the RX buffer 13d are cleared to empty. The HCI 12 inputs the map area data input in this manner to the API 11, the API 11 inputs the input map area data to the main CPU 33, and the main CPU 33 inputs the input map area data. Is used to execute necessary processing (for example, map display processing using data of the specific map area).

  Subsequently, in step 645, it is determined whether or not all the data in the map area has been recorded in the map storage medium 8 based on whether or not the last packet of the data in the map area has been recorded in the map storage medium 8. If it is determined that it is not, the process returns to step 625. Thus, if the writing speed is faster than the communication speed until all the data of the specific map area that is necessary data is recorded (step 625), the writing address is determined (step 630), and the RX buffer 13d is fully stored. The process waits until the state is reached (step 635), and when the full storage state is reached, the contents of the RX buffer 13d are recorded in the map storage medium 8 and acquired by the HCI 12 (step 640). Note that the write address of step 630 in this repetition is shifted by the size of the RX buffer 13d each time it is executed.

  The processing contents of steps 650, 655, 660, 665, 670, and 675 are the same as those of steps 250, 255, 260, 265, 270, and 275 in FIG. However, the map area corresponding to the record to be added here is a record corresponding to the data of the necessary map area.

  If it is determined in step 625 that the communication speed is equal to or higher than the writing speed (writing cannot be caught up), the writing to the map storage medium 8 is abandoned and only the acquisition by the HCI 12 is performed. Whether or not the RX buffer 13d is in the full storage state is repeated until it is determined that the RX storage 13 is in the full storage state, based on the map area data packet received from. If it is determined that the full storage state is reached, then in step 685, the data in the RX buffer 13d is acquired in the work memory of the HCI 12 via the ECC circuit 13e in the same manner as in step 640, and further output to the main CPU 33. .

  Subsequently, in step 690, it is determined whether or not the HCI 12 has acquired all the data in the map area. If it is determined that the data has not been acquired, the process returns to step 680. In this way, every time the RX buffer 13d is in a full storage state (step 685) until the entire data of the map area that is necessary data is acquired (step 685), the content of the RX buffer 13d is acquired by the HCI 12 (step 685). repeat.

  If it is determined in step 690 that the HCI 12 has acquired all the data in the map area, then in step 695, store execution is performed. Specifically, by executing the processing of steps 215 to 275 in FIG. 7 with a specific map area (necessary data) that has been given up being recorded in the map storage medium 8 as a target map area to be downloaded, The map area data is recorded in the map storage medium 8, and then the processing of FIG.

  By doing in this way, the data which gave up recording in the map storage medium 8 with acquisition by HCI12 can be received again from the center 2, and can be recorded in the map storage medium 8 later. The store execution process in step 695 may be executed when the communication speed becomes lower than the write speed.

  As described above, when the API 11 is instructed by the navigation device 3 to acquire data of a specific map area through communication and output the data to the navigation device 3, the communication speed with the center 2 is transmitted to the map storage medium 8. When the writing speed is lower than the writing speed, that is, when there is a margin in writing, the received data of the specific map area and the error detection code are recorded in the map storage medium 8 and output to the navigation device 3, while the communication speed is written. When the speed is higher than the speed, that is, when the writing cannot catch up, the writing to the map storage medium 8 is given up, and the data of the specific map area and the data of the error detection code are received from the center 2 again later. Can be recorded.

  Further, the API 11 inputs a read command to the HCI 12 so as to read the map area, which is necessary data, from the map storage medium 8 in step 530 of FIG. This read command includes the area ID of the map area, which is necessary data.

  The HCI 12 starts the processing shown in FIG. 13 based on receiving this read command. First, in step 710, the demodulator unit 13f controls the switch circuit 13f to connect the RX buffer 13d to the map storage medium 8 and prevent unnecessary data from entering the RX buffer 13d by performing unnecessary reception. The operation of 13b is stopped. About the modulation | alteration part 13a, it may be made to operate | move and an operation | movement may be stopped. Subsequently, in step 715, the read address of the necessary data is determined by referring to the record including the area ID in the read command in the management table.

  In step 720, necessary data is read from the read address to the work memory of the HCI 12. Specifically, a read command and a read address designation are output to the map storage medium 8. The reading address designation value is the reading address determined in the immediately preceding step 715.

  At this point, since the RX buffer 13d and the map storage medium 8 are connected, the data recorded at the read address of the map storage medium 8 is output to the RX buffer 13d by the read command and the read address designation output. Read out.

  Subsequently, in step 725, the RX buffer 13d waits until the data read from the map storage medium 8 is in a full storage state. When the RX buffer 13d is in the full storage state, subsequently, in step 730, the contents of the RX buffer 13d are transferred to the ECC circuit 13e. To the work memory of the HCI 12. At this time, error correction is performed in the ECC circuit 13e. Note that the ECC circuit 13e waits until data for one packet is acquired from the RX buffer 13d, and at the time when one packet is acquired, error correction is performed on the data in the map area in the packet, and the corrected data is transferred to the HCI 12 Output to. Further, the HCI 12 outputs the data obtained in this way to the main CPU 33 via the API 11.

  Subsequently, in step 735, it is determined whether or not the HCI 12 has acquired all the data of the map area, which is necessary data. If it is determined that it has not been acquired, the process returns to step 710. Thus, until all the data in the map area, which is necessary data, is acquired, a read address is determined so that the necessary data can be read (step 715), and at the timing when the RX buffer 13d is in a full storage state (step 725), The process of acquiring the contents of the RX buffer 13d by the HCI 12 via the ECC circuit 13e (step 730) is repeated. Note that the read address in step 715 in this repetition is shifted by the size of the RX buffer 13d each time it is executed.

  Note that the read address in step 715 in this repetition is shifted by the size of the RX buffer 13d each time it is executed. In this way, necessary data can be sequentially read into the RX buffer 13d.

  If it is determined in step 735 that the HCI 12 has acquired all the data in the map area, the processing in FIG. 13 is terminated. By such processing of FIG. 13, the main CPU 33 of the data in the map storage medium 8 can acquire, and error correction can be performed by the ECC circuit 13e at the time of reading.

  When the ECC circuit 13e finds an error that cannot be corrected in step 730 of the process of FIG. 13, the ECC circuit 13e outputs that fact to the HCI 12, and the HCI 12 cannot correct it by performing the process of FIG. Data of the map area including the error may be received from the center 2 and acquired.

  In addition, when reading data from the map storage medium 8, not only the map area data as described above, but also guidance route data, management table data, peripheral facility and destination list data, history data 13 is read from the map storage medium 8 according to the processing shown in FIG. 13, and is input to the main CPU 33 via the RX buffer 13d, the ECC circuit 13e, the HCI 12, and the API 11. That is, the map storage medium 8 can be read and written by designating an address to the API 11 like a normal memory.

[Erase processing]
Next, erasure of data in the map storage medium 8 will be described. First, the main CPU 33 specifies an area ID of data to be deleted in the map storage medium 8 (or an ID of a route, which is the same in the following description of data deletion), and determines whether it is forced deletion. The erase command is output to the API 11. This erase command includes an area ID of data to be erased and a flag indicating whether or not to force erase.

  As a method for specifying the area ID of data to be erased by the main CPU 33, the area ID to be erased may be determined at random, or from the HCI 12 by the processing of step 825 or 835 described later. When the notification of the area ID having the lowest priority is received, the received area ID may be adopted as the area ID to be deleted.

  Whether or not to perform forced erasure may be fixedly determined according to a predetermined setting (for example, it is always determined that it is not forced erasure) or either according to a user's setting operation. You may come to decide.

  The API 11 that has received this erasure command executes processing as shown in FIG. First, in step 810, the area ID included in the erase command is read to identify the erase target. Subsequently, in step 815, it is determined whether or not forced erasure is performed by reading the flag included in the erasure command.

  If it is determined to be forced erasure, then, in step 845, an erasure command including the area ID is output to the HCI 12, and the processing in FIG. The HCI 12 that has received the erase command specifies an address corresponding to the area ID included in the received erase command from the management table, and inputs the address designation and erase command of the address to the map storage medium 8, thereby The ID data is deleted from the map storage medium 8. As a result, a new free area is created in the map storage medium 8.

  If it is determined in step 815 that it is not forced erasure, the process proceeds to step 820, where the priority corresponding to the area ID is compared with the priority corresponding to another area ID in the management table, and the area It is determined whether or not the priority corresponding to the ID is the lowest value. If it is determined that the value is the lowest value, the process proceeds to step 830.

  If it is determined in step 820 that the value is not the lowest value, the process proceeds to step 825 to notify the main CPU 33 of the other area ID having the lowest value in the management table, and then the deletion is stopped in step 840. The process of FIG. 14 is terminated. The area ID notified to the CPU 33 in this way is included in the erasure command later and input to the API 11, and erasure is realized at that time.

  In step 830, the update date / time corresponding to the area ID is compared with the update date / time corresponding to another area ID in the management table to determine whether the update date / time corresponding to the area ID is the oldest. . If it is determined that it is the oldest, the process proceeds to step 845, where a deletion command including the area ID is output to the HCI 12, and the processing of FIG. 14 is terminated, thereby deleting the data of the area ID from the map storage medium 8.

  If it is determined in step 830 that it is not the oldest, the process proceeds to step 835 to notify the main CPU 33 of the other area ID having the oldest update date and time in the management table, and then the erasure is stopped in step 840. FIG. Terminate the process. The area ID notified to the CPU 33 in this way is included in the erasure command and input to the API 11 later, and erasure is realized at that time.

If erasure is performed in step 845, the main CPU 33 is notified of the erasure. In this way, the data with the lowest priority or the data with the oldest update date / time can be preferentially erased.
[Specific operation example]
Hereinafter, specific operations using the above-described various processes (and other processes) in the communication system as described above will be exemplified.

  When the navigation device 3 is turned on and the navigation device 3 is activated, the main CPU 33 initializes the map storage device 6 with a communication function and establishes a connection between the main CPU 33 and the map storage device 6 with a communication function. . Thereafter, the main CPU 33 estimates the current location based on the signal from the position detection unit 32, includes the area ID of the map area including the current location in the API 11 in the data request, and inputs this data request to the API 11.

  Then, the API 11 executes the processing shown in FIG. 10, determines the necessity of communication depending on whether or not the data of the map area is stored (step 510), controls the HCI 12 according to the determination result, The HCI 12 performs the process of FIG. 12 or FIG. 13 according to this control, so that the main CPU 33 can acquire and display the specific map data. As described above, since the API 11 determines whether or not to perform communication, the main CPU 33 does not need to specify communication start.

  Thereafter, before starting another process, the main CPU 33 includes the storage execution start condition (for example, when reading the next map data after one hour) in the store start request, and inputs this store start request to the API 11. . Then, the API 11 starts the processing of FIG. 6 when the storage execution start condition in the store start request is satisfied, and records the data of the map area to be downloaded in the map storage medium 8.

  In the main CPU 33, it is necessary to initialize devices (display device 4, radio tuner 5, etc.) other than the map storage device 6 with a communication function. During this initialization, the map storage device 6 with a communication function automatically Completes the reception and storage of data in the map area adjacent to the map area including the current location. For this reason, even if not all maps are stored in the map storage medium 8 in advance, the necessary amount can be taken in with a simple procedure.

  Next, consider a case where the main CPU 33 acquires a map around the destination and displays it on the display device 4 in order for the user to set the destination. In this case, a map including the destination may be displayed by (1) a method of scrolling the map to display the destination and (2) name search, telephone number search, address search, genre search, or the like. As described above, the main CPU inputs a data request including the area ID of the map area to be displayed to the API 11, whether or not the map area data has been recorded in the map storage medium 8 at the time of activation. As a result, the map data can be acquired in the same manner as when all the maps are stored in the map storage medium 8.

  The reason why the API 11 determines whether or not to perform communication is that the product using the map storage medium 8 having a capacity capable of recording all necessary data can operate without communication. This is because there is no need to change the processing content of the main CPU 33 even when using a product or using a product using the map storage medium 8 that does not have the capacity to record all necessary data. In this way, the necessity of changing the design of the navigation device 3 according to the performance of the map storage device 6 with communication function is reduced.

  When the free space of the map storage medium 8 is small and the communication band with the center 2 is also small, the main CPU 33 cannot read the map area data in real time in accordance with the scroll operation even if a data request is input. As a result, there is a possibility that the map cannot be scrolled. In such a case, the method of reading the destination map (2) may be used. That is, when the map area to be displayed exceeds the scrollable area (the range of the acquired map area), a screen for searching for a destination by searching is displayed.

  In that case, the main CPU 33 determines in step 305 in FIG. 8 that all maps necessary for route calculation are not stored, and in step 310, sends the destination to the center 2 using communication, In step 315, the guidance route data is received from the center 2, the received guidance route is displayed on the display device 4, and the map area data including the destination is read from the map storage medium 8.

  Further, when the guide route is very long and all the route data of the guide route cannot be recorded in the map storage medium 8 as in a long-distance drive, the main CPU 33 first calculates only a part of the route and calculates the map storage medium. 8, a map area including a point at which the part of the route and the remaining route are switched is specified, and when the map area is read, the remaining route is calculated and recorded in the map storage medium 8. It may be.

  If the vehicle moves according to the route guidance of the guidance route, the main CPU 33 reads the map data in accordance with the area ID recorded in the guidance route data, and the map storage device with communication function 6 corresponds to the map data corresponding to the request of the main CPU 33. Is output. If the store start trigger condition is satisfied when the map area data is read out, the next map area is sequentially stored in the map storage medium 8 along the route data by the processing of FIGS. .

  Even if the route guidance is not performed, if the trigger condition is met when the map area data is read out, if it is, when the data in a certain map area is read out, Data of adjacent map areas is downloaded from the center 2 and accumulated in the map storage medium 8. As a result, the area that continuously travels in the same map area such as the neighborhood of the home, the priority of the data of the map area in that area is increased by the processing of FIG. 11, so that the necessary data is always stored in the map storage medium 8. Accumulated and communication for acquiring map area data gradually becomes unnecessary.

  As described above, when the data of the map area to be downloaded, the error correction code, etc. are transmitted from the center 2 to the in-vehicle system 1, the HCI 12 sends the data of the map area to be downloaded and the error correction code to the RX buffer 13d. Then, control is performed so as to be written into the map storage medium 8 via the switch circuit 13f (see steps 210 to 245 in FIG. 7).

  Further, the HCI 12 receives the read command from the navigation device 3 to read the downloaded map area data from the map storage medium 8, and the map area data stored in the map storage medium 8 and the error correction are stored. The code is controlled to be input to the ECC circuit 13e via the RX buffer 13d and the switch circuit 13f (see steps 710 to 735 in FIG. 13), and the ECC circuit 13e receives the data and error of the map area from the map storage medium 8. When a correction code is input, the error correction code is used to perform error correction of the map area data to be downloaded, and the error-corrected map area data is input to the HCI 12, and the HCI 12 The map area data is converted into a navigation device via API 11 And outputs it to.

  As described above, when the map area data and the error correction code received from the center 2 are recorded in the map storage medium 8 without passing through the error correction process, and the map area data is used by the navigation device 3, the map area By inputting the data and the error correction code into the ECC circuit 13e, the error correction performed separately at the time of data reception and at the time of data read can be combined into one by performing error correction. Therefore, redundancy of error correction can be prevented. Also in this way, data errors at the time of reception can be recorded and data errors at the time of reading can be corrected.

In the above embodiment, the navigation device 3 functions as an example of a map display device, the API 11 and the HCI 12 function as an example of a control interface, the ECC circuit 13e functions as an example of a correction code circuit, and the switch circuit 13f is a connection circuit. The modulation unit 13a, the demodulation unit 13b, and the RF circuit 7 function as an example of a radio unit.

(Other embodiments)
As mentioned above, although embodiment of this invention was described, the scope of the present invention is not limited only to the said embodiment, The various form which can implement | achieve the function of each invention specific matter of this invention is included. It is. For example, the following forms are also acceptable.

  (1) In the above embodiment, the API 11 automatically determines which of the map area data is to be deleted. However, in order to secure the storage area of the map storage medium 8 before moving over a long distance, or when returning to the home after moving over a long distance, the data of the map area to be deleted is sent to the user. The data designated by the inquiry and the user may be deleted. Or, when you have finished moving along a long-distance guidance route and returned to your home, ask the user whether to erase the long-distance movement guidance route data and the map area data that includes part of the guidance route. The presence or absence of erasure may be controlled according to the inquiry result.

  (2) Further, if the same data is stored for a long time, the map data may become old, or the data may be damaged due to retention or read disturb of the map storage device 6 with a communication function. As a countermeasure against this problem, the ECC circuit 13e performs data error correction. However, the API 11 or the main CPU 33 periodically receives data of all map areas in the map storage medium 8 from the center 2 to store the map. Rewriting may be performed on the medium 8. In this way, data can be retained for a longer time. For this reason, the API 11 or the main CPU 33 rewrites all data stored in the map storage medium 8 at regular intervals (or at regular intervals) after the navigation device 3 starts operating. It may be. However, reception and rewriting may be skipped when the update date is newer than a predetermined reference.

  (3) In the above embodiment, the ECC circuit 13e that performs error correction (error detection and correction) is employed as an example of an error control circuit that performs error detection. You may employ | adopt the error control circuit which does not perform. In this case, in this case, data used in the error control circuit is not an error correction code but an error detection code having no error correction function. An error correction code is also a kind of error detection code.

  (4) Further, in the above embodiment, the API 11 performs the following steps 125, 135, and 145 in FIG. 6: data on the map area near the guidance route, data on the map area adjacent to the map area read last, and wireless connection The data of the map area adjacent to the map area including the position of the other party's wireless base station is selected as the data to be received from the center 2 and recorded in the map storage medium 8. The map area data to be selected as the target data to be recorded on the medium 8 is not limited to such a person. For example, among the map areas including a part of the guide route, the map area including an area that cannot be communicated on the guide route. May be selected as data to be received from the center 2 and recorded in the map storage medium 8.

  (5) In the above embodiment, the API 11 and the HCI 12 are separate devices, but one microcontroller may realize both functions of the API 11 and the HCI 12.

  (6) In the above embodiment, the navigation device 3 is used as an example of the map display device. However, the map display device is not necessarily a navigation device, and the map storage medium 8 of the map storage device 6 with a communication function is used. Any device that does not have a navigation function may be used as long as the map display is performed using the recorded map data.

  (7) In the above embodiment, the navigation device 3 and the map storage device 6 with a communication function constitute an in-vehicle system mounted on a vehicle. However, the navigation device 3 and the map storage device 6 with a communication function are provided to a pedestrian. It may be a portable system. That is, the navigation device 3 and the map storage device 6 with a communication function may constitute a movable movement system.

  (8) In the above embodiment, the switch circuit 13f is used as an example of a connection circuit for connecting the map storage medium 8 to the TX buffer 13c and the RX buffer 13d. However, the map storage medium 8 is for data writing. If there are two data read terminals and a data read terminal, the TX buffer 13c is connected to the first data write terminal and the second data write terminal and data read terminal are connected. A circuit in which the RX buffer 13d is connected to the terminal for use may be used as the connection circuit.

  (9) In the above embodiment, the switch circuit 13f is switched so as to be connectable to the TX buffer 13c. However, if there is no need to write from the TX buffer 13c to the map storage medium 8, the TX buffer 13c is switched. It is not necessary to be connected to the map storage medium 8 via the circuit 13f. In this case, the management table described above may be stored in a non-volatile storage medium (for example, flash memory) included in the HCI 12.

  (10) The trigger condition for determining that the main CPU 33 is established in step 105 in FIG. 5 may be settable by the user. For example, the trigger condition may be set as one of the operation settings of the navigation device 3 (screen color, guidance method, etc.).

  (11) Moreover, in the said embodiment, although the range of a map area is made into the range of 10 km square, it is not necessary to restrict to 10 km. Instead of the 10 km range, the range may be such that the number of times of reading the map area data is optimal. For example, a relatively wide map area may be adopted on a mountain road with a wide movement range, and a relatively narrow map area may be adopted in a city center where roads are crowded. It is also conceivable to set the range of the map area so that the travel time is constant.

  (12) In the above embodiment, the number of data packets in one map area is the same. For the management of map data, it is considered more convenient to have the same size. As described above, when the amount of information is extremely different depending on the map area, the number of communication packets may be changed for each map area. In such a case, the size of each map data may be recorded in the management table, and the number of map packets may be calculated when the map area is read.

  (13) In the above embodiment, the management table is recorded in the map storage medium 8, but is not stored in the map storage medium 8 but in a nonvolatile storage medium (for example, a flash memory) provided in the API 11. Or may be stored in a non-volatile storage medium provided in the HCI 12 or the work memory 31 of the navigation device 3.

  (14) In the above embodiment, each function realized by the main CPU 33, API 11, and HCI 12 executing a program is capable of programming hardware having those functions (for example, a circuit configuration can be programmed). (FPGA) may be used.

DESCRIPTION OF SYMBOLS 1 In-vehicle system 2 Center 3 Navigation apparatus 4 Display apparatus 6 Map storage apparatus 7 with a communication function RF circuit 8 Map storage medium 9 Control part 11 API
12 HCI
13 Baseband unit 13a Modulating unit 13b Demodulating unit 13c TX buffer 13d RX buffer 13e ECC circuit 13f Switch circuit 30 ROM
31 Work memory 32 Position detector 33 Main CPU

Claims (6)

An in-vehicle system that communicates with the center (2) that transmits the map area data to be downloaded with the error detection code of the map area data to be downloaded added thereto,
A map display device (3) for displaying a map and a map storage device (6) with a communication function;
The map storage device with communication function (6) includes a map storage medium (8), a control interface (11, 12), a radio unit (13a, 13b, 7), an error control circuit (13e), and the radio Connecting circuits (13c, 13d) that can connect the units (13a, 13b, 7) to the map storage medium (8) and can connect the map storage medium (8) to the error control circuit (13e). , 13f)
The radio unit (13a, 13b, 7) receives the radio signal including the data of the map area to be downloaded and the error detection code transmitted from the center (2), and performs frequency conversion on the received radio signal. And demodulate,
The control interface (11, 12) is configured such that the data of the map area to be downloaded and the error detection code obtained as a result of frequency conversion and demodulation by the radio units (13a, 13b, 7) are stored in the connection circuit ( 13c, 13d, 13f) to be written to the map storage medium (8),
In addition, the control interface (11, 12) receives the read command from the map display device (3) to read out the data of the map area to be downloaded from the map storage medium (8). Control is performed so that the data of the map area to be downloaded and the error detection code stored in the storage medium (8) are input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f). And
The error control circuit (13e) receives the map area data to be downloaded and the error detection code from the map storage medium (8) via the connection circuit (13c, 13d, 13f). The error detection code is used to perform error detection of the data of the map area to be downloaded, and the data of the map area to be downloaded without error that has undergone error detection is input to the control interface (11, 12),
The mobile system according to claim 1, wherein the control interface (11, 12) outputs the input map area data to be downloaded after the error detection to the map display device (3).   The control interface (11, 12) receives any store start request that does not specify the data of the map area to be acquired from the map display device (3), and is any section in a predetermined route. The map area data including the map area or the map area data adjacent to the map area including the position of the map storage device with communication function (6) is used as the download target map area. The moving system described in. The wireless unit (13a, 13b, 7) receives the position of the wireless base station wirelessly transmitted by the wireless base station,
When the control interface (11, 12) receives from the map display device (3) a store start request that does not specify the data of the map area to be acquired, the radio unit (13a, 13b, 7) 2. The mobile system according to claim 1, wherein the received map area data adjacent to the map area including the position of the wireless base station is used as the map area to be downloaded. The control interface (11, 12) is a recording / transfer command for instructing to output data to the map display device (3) while acquiring data of a specific map area by communication and recording it in the map storage medium (8). Is transmitted to the center (2) through the wireless unit (13a, 13b, 7), the data request signal including the ID of the specific map area,
When the center (2) receives the data request signal and transmits the data of the specific map area indicated by the ID included in the data request signal with the data error detection code of the map area being transmitted, The radio unit (13a, 13b, 7) receives the radio signal including the data of the specific map area and the error detection code transmitted from the center (2), and performs frequency conversion and demodulation on the received radio signal. And
The control interface (11, 12) compares the communication speed with the center (2) with a predetermined writing speed to the map storage medium (8),
In addition, the control interface (11, 12) may be configured to obtain the specific information obtained as a result of frequency conversion and demodulation by the wireless unit (13a, 13b, 7) when the communication speed is lower than the writing speed as a result of comparison. The map area data and the error detection code are controlled to be written into the map storage medium (8) via the connection circuit (13c, 13d, 13f), and the radio unit (13a, 13b, 7) is controlled. Control is performed so that the data of the specific map area and the error detection code obtained as a result of frequency conversion and demodulation are input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f). ,
Further, the control interface (11, 12) may be configured such that, when the communication speed is higher than the writing speed as a result of the comparison, the specific part obtained as a result of the frequency conversion and demodulation by the radio unit (13a, 13b, 7). The map area data and the error detection code are input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f) without being recorded in the map storage medium (8). Control
When the data of the specific map area and the error detection code are input via the connection circuit (13c, 13d, 13f), the error control circuit (13e) Error detection of map area data is performed, and the data of the specific map area without error that has passed through error detection is input to the control interface (11, 12),
The control interface (11, 12) outputs the input data of the specific map area after error detection to the map display device (3),
The control interface (11, 12), when the communication speed is higher than the writing speed as a result of comparison, the data of the specific map area and the error detection code are input to the error control circuit (13e). Later, the center (2) transmits the data of the specific map area as data of the map area to be downloaded together with an error detection code of the data of the specific map area so as to transmit the data. The mobile system according to any one of claims 1 to 3, wherein a data request signal including an ID of the specific map area is transmitted to the center (2) via 7). The map display device (3) includes a work memory (31) and an arithmetic circuit (33), and is a navigation device that calculates a guide route from a current location to a destination,
The calculation circuit (33) has a higher calculation speed than the control interface (11, 12), the work memory (31) has a larger capacity than the memory provided in the control interface (11, 12),
The arithmetic circuit (33) determines whether or not the current location and the destination are in the same one map area, and if it is determined that they are in the same one map area, the control interface (11, 12) ) To calculate the guidance route, and when it is determined that the route is not within the same one map area, the calculation circuit (33) itself uses the work memory (31) to calculate the guidance route. The mobile system according to any one of claims 1 to 4. A map storage device with a communication function for communicating with a center (2) for transmitting the map area data to be downloaded with an error detection code of the map area data to be downloaded,
The control interface (11, 12), the radio unit (13a, 13b, 7), the map storage medium (8), the error control circuit (13e), and the radio unit (13a, 13b, 7) are stored in the map storage. A connection circuit (13c, 13d, 13f) that is connectable to the medium (8) and that can connect the map storage medium (8) to the error control circuit (13e);
The radio unit (13a, 13b, 7) receives the radio signal including the data of the map area to be downloaded and the error detection code transmitted from the center (2), and performs frequency conversion on the received radio signal. And demodulate,
The control interface (11, 12) is configured such that the data of the map area to be downloaded and the error detection code obtained as a result of frequency conversion and demodulation by the radio units (13a, 13b, 7) are stored in the connection circuit ( 13c, 13d, 13f) to be written to the map storage medium (8),
Further, the control interface (11, 12) is based on receiving a read command for reading the data of the map area to be downloaded from the map storage medium (8) from the map display device (3) for displaying a map. The map area data to be downloaded and the error detection code stored in the map storage medium (8) are input to the error control circuit (13e) via the connection circuit (13c, 13d, 13f). To be controlled and
The error control circuit (13e) receives the map area data to be downloaded and the error detection code from the map storage medium (8) via the connection circuit (13c, 13d, 13f). The error detection code is used to perform error detection of the data of the map area to be downloaded, and the data of the map area to be downloaded after the error detection is input to the control interface (11, 12),
The said control interface (11, 12) outputs the data of the said map area of the download object after the input error detection to the said map display apparatus (3), The map storage apparatus with a communication function characterized by the above-mentioned.

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