JP5851819B2 - Data writing / reading apparatus and data writing / reading method - Google Patents

Description

  The present invention relates to a data writing / reading apparatus and a data writing / reading method, and more particularly to a data writing / reading apparatus and a data writing / reading method for storing sequentially generated data in a memory that cannot be overwritten.

  For alarm devices such as gas leaks and fires, the setting data (eg gas concentration alarm value) set at the time of shipment from the factory, the alarm history at the time of alarm occurrence, the failure history at the time of failure occurrence, the energization time, etc. are recorded in the EEPROM. ing. However, in order to store these data, it is necessary to increase the capacity of the EEPROM, which causes a problem in cost.

  Recently, it has been considered to use flash memory inside a microcomputer constituting an alarm device in place of EEPROM to store these data. This eliminates the need for an EEPROM and reduces costs.

  However, unlike the EEPROM, the flash memory cannot overwrite data. For this reason, conventionally, every time data is generated, all types of data (that is, setting data, energization time, alarm history, failure history) are added to the flash memory.

  This will be described in detail with reference to FIGS. That is, first, at the time of factory shipment, for example, when a shipment operation is performed, the CPU in the alarm device divides the flash memory area into two blocks B1 and B2 as shown in FIG. The data stored in both the blocks B1 and B2 are erased to make a free area.

  Next, as shown in FIG. 12B, the CPU in the alarm device writes the setting data received by communication from the outside at the head of the block B1. Next, the CPU in the alarm device writes in the block B1 in the order of energization time, alarm history 1 to 3, and failure history 1 to 3. Since it is the time of shipment at this time, 0 is written as the energization time. In addition, since no alarm or failure has occurred, empty data is written as the alarm histories 1 to 3 and the failure histories 1 to 3.

  Further, these energization times, alarm histories 1 to 3 and failure histories 1 to 3 all have the same data length, so that a data length adjustment area has a data length adjustment area shorter than the maximum data length. Is provided. For example, as the energization time, several tens of bytes are written together with long data such as alarm histories 1 to 3 and failure histories 1 to 3 where a few bytes can be written.

  Thereafter, when an alarm is generated, the CPU in the alarm device moves the alarm history 2 to the alarm history 1, the alarm history 3 to the alarm history 2, and the new alarm history as the alarm history 3 as shown in FIG. All types of data (setting data, energization time data, alarm histories 1 to 3 and failure histories 1 to 3) are added. Thereafter, when a failure occurs, the CPU in the alarm device moves the failure history 2 to the failure history 1 and the failure history 3 to the failure history 2 as shown in FIG. Append all types of data.

  Thereafter, when the clocking for each predetermined time is completed after the installation, the CPU in the alarm device adds all kinds of data with the new energization time obtained by adding the predetermined time as the energization time, as shown in FIG. . When writing to the end of the block B1, the CPU in the alarm device erases all the data stored in the block B2 to make a free space as shown in FIG. Next, as shown in FIG. 16B, the CPU in the alarm device has the latest all types of data (that is, the first of all types of data stored in the block B1) at the beginning of the erased block B2. Write back all data types).

  When a setting device that reads data in the flash memory is connected to this alarm device, the alarm device determines whether or not data has been written from the area after block B2, and reaches the area to which data has been written. Then, the energizing time, the alarm history 1 to 3 and the data for each equal data length of the failure history 1 to 3 are set as the latest failure history 3-1, the latest alarm history 3-1, the latest energizing time, and the setting device. Send to.

  Thus, conventionally, every time data is generated, all types of data (that is, setting data, energization time, alarm history, failure history) are additionally written in the flash memory, so that the efficiency is low. Further, since the flash memory has a smaller number of erasable times than that of the EEPROM, it is necessary to reduce the number of times data is written, and there is a problem in use in an alarm device.

  Therefore, the present invention provides a data writing / reading apparatus and a data writing / reading device that can reduce the number of times of erasing by reducing the amount of data to be written each time data is generated, and can efficiently use a memory that cannot be overwritten. It is an object to provide a method.

An invention according to claim 1 for solving the above-described problem is provided in a data writing / reading apparatus which is mounted on a device and sequentially writes a plurality of types of data generated in a non-overwriteable memory. The latest block setting means for setting one of the plurality of blocks as the latest block, and the occurrence of the data in order from the head of the empty area of the latest block every time the data is generated or every predetermined time elapses. Writing / reading means for writing data or data obtained by adding a data type or data length to elapsed time data from the start of use of the device, free space determining means for determining whether or not there is a free space in the latest block, If the free space determination means determines that there is no free space, the free space is determined as at least one of the other blocks excluding the latest block. And erasing means for totally erasing the data, after being totally erased by said erasing means, by the erasing unit of data from the most recent or current to a predetermined one before each type of data written in the newest block Data writing means for sequentially writing to the head of other erased blocks, and the latest block setting means sets the other blocks as the latest blocks after the writing by the data writing means is completed. It exists in the data writing / reading apparatus characterized.

According to the second aspect of the present invention, the data writing means reads data sequentially from the back of the latest block after being completely erased by the erasing means, and is based on the data type or data length to which the data is added. 2. The data from the back or from the back to a predetermined number of times is extracted every time, and the extracted data is written in order from the head of another block that has been completely erased by the erasing means. It exists in the data writing / reading apparatus of description.

  According to a third aspect of the present invention, overwriting means for overwriting at least one type of data among a plurality of types of data written by the writing / reading means in the overwritable second memory each time the writing / reading means writes the data. And the data writing means reads the data in order from the rear of the latest block after being completely erased by the erasing means, and based on the data type or data length added to the data, the second memory The data from the back or the back to the predetermined number is extracted for each type excluding the type overwritten by the data, and the data stored in the second memory and the extracted data are extracted by the erasing means 2. The data writing / reading apparatus according to claim 1, wherein writing is performed in order from the head of the other erased blocks.

  According to a fourth aspect of the present invention, the elapsed time data is written in the memory, the elapsed time data stored in each block is compared, and the block in which the maximum elapsed time is written is determined as the latest block. The latest block determination means, and the writing / reading means reads the data in order from the back to the front of the latest block, and determines the first for each type based on the data type or data length added to the data. The data writing / reading apparatus according to any one of claims 1 to 3, wherein the data from the back or from the back to a predetermined number is read.

  According to a fifth aspect of the present invention, the writing / reading means and the data writing means determine a data length from a data type added to the data and determine an area in which the data is written. The data writing / reading apparatus according to claim 1, wherein the data writing / reading apparatus is provided.

According to a sixth aspect of the present invention, in a data writing / reading method for writing a plurality of types of data that are sequentially generated in a memory that is mounted on a device and cannot be overwritten, a plurality of blocks are provided in an area of the memory, The latest block setting step for setting one of the blocks as the latest block, and from the start of use of the generated data or the device in order from the top of the empty area of the latest block every time the data is generated or every predetermined time elapses A writing / reading process for writing data obtained by adding a data type or a data length to the elapsed time data, an empty area determining process for determining whether or not there is an empty area in the latest block, and an empty area by the empty area determining process If it is determined that there is no data, the data stored in at least one of the other blocks excluding the latest block is erased completely. A step, after being all erased by the erasing step, the by each type of the latest or the erasing step the data from the most recent to the predetermined or pre-out data written in the newest block of the other blocks has been totally deleted A data writing step of sequentially writing to the head, wherein the latest block setting step sets the other block as the latest block after the writing by the data writing step is completed. Exist.

  As described above, according to the first and sixth aspects of the invention, by adding a data type or a data length to data, every type of data is added every time a predetermined time elapses. Even if only the generated data is added later, it is possible to read the data from the latest block to the latest or a predetermined number of data from the latest block for each type. As a result, the amount of data to be written can be reduced each time data is generated, the number of erasures can be reduced, and a memory that cannot be overwritten efficiently can be used. The predetermined number is determined in advance for each type of data, and may be partially different for each type.

  According to the second aspect of the present invention, the latest block is read from the latest block or the predetermined number of pieces of data for each type, that is, the latest or latest piece of data is read from the latest block, and the beginning of another block is read. Can be written on.

  According to the third aspect of the present invention, the type of data stored in the second memory can be moved to another block without sequentially reading from the back of the latest block.

  According to the invention described in claim 4, the latest block determination means compares the elapsed time data stored in each block and determines the block in which the maximum elapsed time is written as the latest block. Even if it does not have, it can be determined which of the blocks is the latest block.

  According to the fifth aspect of the present invention, the writing / reading means and the data writing means determine the data length from the data type added to the data, and determine the area where the data is written. Therefore, since the data can be specified without making the data length of each type of data the same, there is no need to provide a data length adjustment area for adjusting the data length of each type of data to be the same. Data is not stored in memory.

It is a block diagram which shows one Embodiment of the alarm device incorporating the data writing / reading apparatus of this invention. It is a figure which shows the structure of the energization time written in the flash memory which comprises the data writing / reading apparatus shown in FIG. 1, setting data, an alarm history, and a failure history. It is a flowchart which shows the data writing / reading process procedure of CPU shown in FIG. It is a figure which shows the data stored in the flash memory at the time of factory shipment of the alarm device shown in FIG. It is a figure which shows the data stored in the flash memory at the time of normal time writing of the alarm device shown in FIG. It is a figure which shows the data stored in the flash memory at the time of the alarm generation of the alarm device shown in FIG. It is a figure which shows the data stored in the flash memory at the time of failure occurrence of the alarm device shown in FIG. It is a figure which shows the data stored in the flash memory when writing to the last of the block B1 of the alarm device shown in FIG. It is explanatory drawing for demonstrating the operation | movement at the time of the reading of the alarm device shown in FIG. It is a figure which shows the structure of the energization time written in the flash memory in another embodiment, setting data, an alarm history, and a failure history. It is a figure which shows the structure of the energization time written in the flash memory in another embodiment, setting data, an alarm history, and a failure history. FIG. 0 is a diagram showing data stored in a flash memory at the time of conventional factory shipment. It is a figure which shows the data stored in the flash memory at the time of the conventional alarm generation. It is a figure which shows the data stored in the flash memory at the time of the conventional failure occurrence. It is a figure which shows the data stored in the flash memory at the time of the conventional energization time writing. It is a figure which shows the data stored in the flash memory when writing to the last of the conventional block B1.

  The data writing / reading apparatus and data writing / reading method of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an alarm device incorporating the data writing / reading apparatus of the present invention. As shown in the figure, an alarm device 1 as a device includes a microcomputer (hereinafter referred to as μCOM) 2 that controls the alarm device 1 as a whole, a sensor 3 that detects an abnormality such as a gas leak or a fire, and a setting device described later. 4 and an input / output terminal 5 for connecting the terminal 4.

  The μCOM 2 includes a CPU 2A that performs various processes according to a processing program, a ROM 2B that stores a program for processing performed by the CPU 2A, a work area that is used in various processes in the CPU 2A, a data storage area that stores various data, and the like. And a flash memory 2D, which is a non-overwritable non-volatile memory. The CPU 2A performs an alarm generation process for generating an alarm based on an output from the sensor 3, a failure detection process for detecting a failure, and the like.

  The flash memory 2D is provided with two blocks B1 and B2 in the memory area. In the flash memory 2D, data such as energization time, set value data, alarm history, and failure history are sequentially written. As shown in FIGS. 2A to 2D, the data such as energization time, setting data, alarm history, and failure history include an area in which a checksum is written at the beginning and a data type at the end (that is, energization time, setting). An area for writing data), and an area for writing the data itself between the checksum and the data type. These data have different data lengths depending on the data type, the longest setting data, the longest alarm history and failure history, and the shortest energization time.

  Next, the operation of the data writing / reading apparatus having the above-described configuration will be described with reference to FIGS. FIG. 3 is a flowchart showing a processing procedure in the data writing / reading process of the CPU 2A constituting the data writing / reading apparatus shown in FIG. FIG. 4 is a diagram showing data stored in the flash memory 2D when the alarm device 1 shown in FIG. 1 is shipped from the factory. FIG. 5 is a diagram showing data stored in the flash memory 2D at the time of writing the energization time of the alarm device 1 shown in FIG. FIG. 6 is a diagram showing data stored in the flash memory 2D when an alarm is generated by the alarm device 1 shown in FIG. FIG. 7 is a diagram showing data stored in the flash memory 2D at the time of failure of the alarm device 1 shown in FIG. FIG. 8 is a diagram showing data stored in the flash memory 2D when writing to the end of the block B1 of the alarm device 1 shown in FIG.

  At the time of factory shipment, only the energization time (0 hour) and setting data are stored at the head of the latest block B1 of the flash memory 2D. Thereafter, the CPU 2A starts the data writing / reading process in response to power-on. The CPU 2A performs the alarm generation process and the failure detection process described above in parallel with the data writing / reading process. In step S1, the CPU 2A functions as an empty area determination unit and determines whether or not the latest block is full. Specifically, the CPU 2A reads data from the end of the latest block, and determines whether or not empty data “0” continues for a predetermined byte or more. The CPU 2A determines that the latest block is full if empty data is not continuous for a predetermined byte or more from the end, and determines that the latest block is not full if empty data is continuous for a predetermined byte or more from the end. This step S1 corresponds to a free space determination step in the claims.

  If it is determined that the latest block is not full (N in Step S1), then the CPU 2A determines whether or not the timing for every predetermined time started after the power is turned on (Step S7). If it is determined that the measurement of the predetermined time has ended (Y in step S7), the CPU 2A determines a predetermined energization time at the beginning of the empty area of the latest block (block B1 in the example of FIG. 5) as shown in FIG. The new energization time 2 added with the time is written, and the energization time stored in the RAM 2C is overwritten with the new energization time (step S8), and the process proceeds to the next step S9. By step S8, the latest energization time is always stored in the RAM 2C. If the measurement of the predetermined time has not ended (N in step S7), the CPU 2A immediately proceeds to step 9 without proceeding to step S8.

  In step S9, the CPU 2A determines whether or not data to be stored in the flash memory 2D is generated due to an alarm or failure, a setting data update request from the setting device 4, and the like. If there is no data to be stored in the flash memory 2D (N in step S9), the CPU 2A immediately returns to step S1. On the other hand, if data to be stored in the flash memory 2D has occurred (Y in step S9), the CPU 2A writes the generated data at the head of the empty area of the latest block (step S10), and then returns to step S1. .

  The details of step S10 will be described. For example, when an alarm is generated, the CPU 2A writes a new alarm history 2 at the head of the free area of the latest block (block B1 in the example shown in FIG. 6) as shown in FIG. . When a failure occurs, the CPU 2A writes a new failure history 3 at the head of the empty area of the latest block (block B1 in the example shown in FIG. 7) as shown in FIG. In steps S7 to S10 described above, the CPU 2A functions as a writing / reading unit. Steps S7 to S10 correspond to the writing / reading step in the claims.

  On the other hand, if it is determined that the latest block is full (Y in step S1), then the CPU 2A functions as an erasing unit as shown in FIG. The data stored in (block B2 in the example of FIG. 8) is completely erased to make a free area (step S2). This step S2 corresponds to an erasing step in the claims. Next, the CPU 2A writes the latest energization time stored in the RAM 2C at the head of another block (step S3).

  Next, as shown in FIG. 8B, the CPU 2A searches the setting data stored in the latest block among the setting data stored in the latest block, and writes it after the energization time (step S4). . After that, as shown in FIG. 8C, the CPU 2A searches the alarm history from the back to the previous three out of the alarm histories stored in the latest block, writes it to the back of the setting data, and thereafter, FIG. As shown in (D), the fault history stored in the latest block is searched from the last three fault histories and written after the alarm history (step S5), and the process proceeds to step S6.

  The above search will be described in detail. First, the CPU 2A starts reading from the end of the latest block (block B1). The CPU 2A stores the data type added to the end of the data at the end. The CPU 2A determines the type of data written at the end of the block B1 from this data type. In the example shown in FIG. 8C, the CPU 2A determines that the alarm history 7 is written at the end of the latest block. The CPU 2A determines the data length of the data from the determined data type, and determines that the data in the area before the determined data length from the area where the data type is written is the data of that data type.

  In the example shown in FIG. 8C, the data in the area from the tail to the previous data length of the alarm history is determined as the alarm history 7. Further, the CPU 2A reads the data toward the head of the latest block, and determines the type of data written before the alarm history 7 from the data type stored in the area before the alarm history 7. In the example illustrated in FIG. 8C, it is determined that the alarm history 6 is written before the alarm history 7. As described above, the CPU 2A sequentially reads data from the back to the front, and searches the alarm history stored in the latest block from the back to the previous three.

  In the example shown in FIG. 8C, the alarm histories 7, 6, and 5 are searched as the alarm histories from the back to the previous three out of the alarm histories stored in the latest block. The CPU 2A sequentially writes the three alarm histories 7, 6, and 5 in the block B2 from the front. That is, the alarm history 5 is moved to the alarm history 1, the alarm history 6 is moved to the alarm history 2, and the alarm history 7 is moved to the alarm history 3. In the example shown in FIG. 8D, the failure histories 6, 5, and 4 are searched as failure histories from the last three to the previous failure histories stored in the latest block. The CPU 2A writes to the block B2 in order from the earliest of these three failure histories 6, 5, and 4. That is, the failure history 4 is moved to the failure history 1, the failure history 5 is moved to the failure history 2, and the failure history 6 is moved to the failure history 3 to be additionally recorded. In steps S3 to S5 described above, the CPU 2A functions as data writing means. Steps S3 to S5 correspond to the data writing step in the claims.

  In step S6, the CPU 2A functions as the latest block setting means, sets the other block (block B2 in the example shown in FIG. 8) as the latest block, and proceeds to the next step S7. This step S7 corresponds to the latest block setting step in the claims.

  Next, an operation when a history reading request is made by the setting device 4 will be described. First, the CPU 2A functions as the latest block determination means, compares the energization times written at the heads of the blocks B1 and B2, and determines the block in which the maximum value is written as the latest block. After that, the CPU 2A functions as a reading unit, reads from the back of the latest block, the first energization time found first is the latest energization time, the first setting data found is the latest setting data, the alarm history from the back to the previous three, and the failure The history is transmitted to the setting device 4 as the latest alarm history and the latest failure history.

  In the example shown in FIG. 9, the CPU 2A determines that the block B2 is the latest block, the energization time 3 is the latest energization time, the setting data 2 is the latest setting data, the alarm histories 4, 3, and 2 are the latest alarm history, and the failure history 3 2 and 1 are transmitted to the setting device 4 as the latest failure history.

  According to the above-described embodiment, the CPU 2A provides the two blocks B1 and B2 in the area of the flash memory 2D, sets one of the two blocks B1 and B2 as the latest block, and sets data (setting data, alarm history, Every time a (failure history) occurs or a predetermined time elapses, data is generated in order from the top of the empty area of the latest block, or a data type is added to the end of the energization time and stored. Further, the CPU 2A determines whether or not there is an empty area in the latest block, and when it is determined that there is no empty area, after erasing data of other blocks excluding the latest block, the data is read sequentially from the back of the latest block. Based on the data type added at the end of the data, the last or last three data is extracted for each type, and the extracted data is written in order from the top of the other blocks. Thereafter, the CPU 2A sets other blocks as the latest blocks after the writing is completed.

  As described above, when data is generated by adding the data type to the end of the data, all types of data (energization time, setting data, alarm history 1 to 3, failure history 1 to 3) are provided as in the conventional example. Even if only the generated data is added after the data, the latest data or the data from the latest to the previous three data can be read for each type from the latest block. As a result, the amount of data to be written can be reduced each time data is generated, the number of erasures can be reduced, and a memory that cannot be overwritten efficiently can be used. Also, the last or third data from the latest block can be read for each type from the latest block and written at the head of another block.

  Further, according to the above-described embodiment, the CPU 2A overwrites and saves the energization time in the RAM 2C, and after all erasure is performed, the latest energization time stored in the RAM 2C is sequentially written from the top of the other blocks. As a result, the latest energization time stored in the latest block can be moved to the beginning of another block without sequentially reading the energization time from the back of the latest block.

  Further, according to the embodiment described above, the CPU 2A compares the energization times stored at the heads of the blocks B1 and B2, determines the block in which the maximum energization time is written as the latest block, and determines the latest block. The data is read in order from the back of the data, and based on the data type added at the end of the data, the last of each type (in the case of energization time and setting data), or the last three (alarm history, Data in the case of a failure history) is read as the latest data, so it is possible to determine which of the blocks is the latest block without having information on the latest block.

  According to the above-described embodiment, the CPU 2A determines the data length from the data type added to the end of the data, and the data in the area up to the determined data length from the area where the data is written, It is determined that the data type is data. Therefore, since the data can be specified without making the data length of the energization time, the alarm history, and the failure history the same as before, the data length for adjusting the data length of each type of data to the same There is no need to provide an adjustment area, and useless data is not stored in the flash memory 2D.

  According to the above-described embodiment, the energization time is overwritten in the RAM 2C, but the present invention is not limited to this. The data written to the RAM 2C may be at least one of data written to the flash memory 2D, and may be an alarm history or a failure history. When the latest block is full, the energization time written in the RAM 2C is moved to another block as the latest one, but the present invention is not limited to this. The latest block of the flash memory 2D may be read and moved to another block.

  Further, according to the embodiment described above, only the energization time is overwritten in the RAM 2C, but the present invention is not limited to this. For example, all types of data stored in the flash memory 2D are overwritten in the RAM 2C in the RAM 2C, so that all types of latest data are stored in the RAM 2C. When the latest block becomes full, all types written in the RAM 2C are stored. The latest data may be moved to another block. In this case, it is not necessary to read the latest data from the latest block, and the processing is simplified.

  Further, according to the above-described embodiment, the CPU 2A determines the latest block from the energization time stored at the head of each of the blocks B1 and B2 at the time of reading by the setting device 4, but the present invention is not limited to this. Not a thing. For example, an area indicating the latest block may be provided in an area different from the blocks B1 and B2 of the flash memory 2D, and the block stored in the area may be determined as the latest block. In this case, when the latest block is full, it is not necessary to write the energization time at the beginning of the other blocks.

  In the embodiment described above, the data type is added at the end, but the present invention is not limited to this. The location where the data type is added need not be at the end. For example, as shown in FIG. 10, the data length is added to the end and the data length is set in the area before the end by a predetermined data length. The data type may be stored.

  In the embodiment, the history type is determined based on the data type added at the end, but the present invention is not limited to this. For example, if the data length is different for each type, the data length may be added before the end or before the end, and the type may be determined from the data length.

  In the above-described embodiment, the data type is added to the tail and the history type is determined based on the data type. However, the present invention is not limited to this. For example, as shown in FIG. 11, the data length is added to each type of data, and the alarm history or failure history is the same for the alarm history and failure history (see FIG. 2) of the present embodiment. A data type that can be distinguished is added. As a result, the data length added to each type of data is read, and if there is only one type of data with the read data length, such as energization time and setting data, the data type is determined based on the data length. If there are two or more types of data with the read data length, the data type may be further read to determine the data type.

  Further, according to the embodiment described above, the flash memory 2D is provided with the two blocks B1 and B2. However, the present invention is not limited to this. As the block, two or more blocks may be provided, and three or four blocks may be provided.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

1 Alarm (device, data writing / reading device)
2A CPU (latest block setting means, writing / reading means, free area judging means, erasing means, data writing means, overwriting means, latest block judging means)
2C RAM (second memory)
2D flash memory (memory)
B1 block B2 block

Claims (6)

In a data writing / reading device for writing a plurality of types of data generated sequentially in a memory that is mounted on a device and cannot be overwritten,
A plurality of blocks are provided in the memory area,
Latest block setting means for setting one of the plurality of blocks as the latest block;
Each time the data is generated or every time a predetermined time elapses, the generated data or the data added with the data type or the data length is sequentially written from the top of the empty area of the latest block. Writing and reading means;
Free space determination means for determining whether or not there is a free space in the latest block;
If it is determined by the free area determination means that there is no free area, erasing means for erasing all data stored in at least one of the other blocks excluding the latest block;
After all erasing by the erasing means, the data from the latest or latest to a predetermined number of pieces of data written in the latest block in order to the head of the other blocks that are all erased by the erasing means Data writing means for writing,
The data writing / reading apparatus, wherein the latest block setting means sets the other block as the latest block after completion of writing by the data writing means. After the data erasing unit is completely erased by the erasing unit, the data is sequentially read from the back of the latest block, and the last or first data for each type based on the data type or data length to which the data is added. 2. The data writing / reading apparatus according to claim 1, wherein data from the back to a predetermined number is extracted, and the extracted data is written in order from the head of another block that has been completely erased by the erasing unit. Overwriting means for overwriting each time at least one type of data written by the writing / reading means is written to the overwritable second memory by the writing / reading means,
After the data erasing unit is completely erased by the erasing unit, the data is read sequentially from the back of the latest block, and is overwritten in the second memory based on the data type or data length added to the data. The data from the back or from the back to the predetermined number is extracted for each type excluding certain types, and the data stored in the second memory and the extracted data are all erased by the erasing means The data writing / reading apparatus according to claim 1, wherein writing is performed in order from the top of another block. The elapsed time data is written to the memory,
Comparing the elapsed time data stored in each block, further comprising a latest block determination means for determining the block in which the maximum elapsed time is written as the latest block,
The writing / reading unit reads data in order from the back to the front of the latest block, and based on the data type or data length added to the data, a predetermined number of data from the back or the back of each type The data writing / reading device according to claim 1, wherein the data writing / reading device is read. 5. The writing / reading means and the data writing means determine a data length from a data type added to the data, and determine an area in which the data is written. The data writing / reading apparatus according to claim 1. In a data writing / reading method for writing a plurality of types of data sequentially generated in a memory that is mounted on a device and cannot be overwritten,
A plurality of blocks are provided in the memory area,
A latest block setting step of setting one of the plurality of blocks as a latest block;
Each time the data is generated or every time a predetermined time elapses, the generated data or the data added with the data type or the data length is sequentially written from the top of the empty area of the latest block. Writing and reading process;
A free space determination step of determining whether there is a free space in the latest block;
If it is determined that there is no free space in the free space determination step, an erasing step of erasing all data stored in at least one of the other blocks except the latest block;
After all erasure by the erasing step, the data from the latest or latest to a predetermined number of types of data written in the latest block in order to the head of the other blocks that are all erased by the erasing step A data writing step for writing,
The data writing / reading method characterized in that the latest block setting step sets the other block as the latest block after completion of writing by the data writing step.

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