TWI751466B - Time synchronization method and time synchronization system - Google Patents

Abstract

A time synchronization method and a time synchronization system are provided. The method includes: establishing a time mapping relationship between a Controller Area Network (CAN) device in a CAN system under a test mode of the CAN device; reading CAN time information of at least one data packet from the CAN device under a normal mode of the CAN device; and recording host time information of the at least one data packet according to the time mapping information and the CAN time information.

Description

Time Synchronization Method and Time Synchronization System

The present invention relates to a time synchronization technology, and in particular, to a time synchronization method and a time synchronization system.

A Controller Area Network (CAN) is a bus standard that can be used in automotive electronic systems or electronic systems in other industries to enable chips and/or electronic devices in the electronic systems to communicate with each other. Nodes in a CAN system are also referred to as CAN devices (or CAN bus devices). Multiple CAN devices can be connected to each other through twisted pairs for communication.

Generally speaking, when a CAN device receives a data packet, the CAN device adds a time stamp to the received data packet according to the built-in clock of the device, and temporarily stores the data packet in a register. Afterwards, the external computer device can read information such as data packets and related packet reception time from the register of the CAN device through communication protocols such as Universal Serial Bus (USB) or Ethernet. However, in practice, the built-in clock of a CAN device often has errors with the real time, and the clocks of different CAN devices may be out of sync with each other, resulting in misjudgment of the receiving time of the data packet by the application program.

The invention provides a time synchronization method and a time synchronization system, which can synchronize the reception time of the data packet received by the CAN device with the time of the host device.

An embodiment of the present invention provides a time synchronization method, which is used in a Controller Area Network (CAN) system. The time synchronization method includes: in a test mode of a CAN device in the CAN system, establishing the time mapping relationship between the CAN device and the host device; in the normal mode of the CAN device, read CAN time information of at least one data packet from the CAN device; and according to the time mapping relationship and the CAN time information, recording the host time information of the at least one data packet.

An embodiment of the present invention further provides a time synchronization system, which includes a host device and at least one CAN device. The at least one CAN device includes a first CAN device and is coupled to the host device. The host device is used for establishing a time mapping relationship between the first CAN device and the host device in the test mode of the first CAN device. The host device is further configured to read CAN time information of at least one data packet from the first CAN device in the normal mode of the first CAN device. The host device is further configured to record host time information of the at least one data packet according to the time mapping relationship and the CAN time information.

Based on the above, in the test mode of the CAN device, the time mapping relationship between the CAN device and the host device can be established. In addition, in the normal mode of the CAN device, CAN time information of at least one data packet can be read from the CAN device. According to the time mapping relationship and the CAN time information, the host time information of the at least one data packet can be recorded, so that the reception time of the at least one data packet is synchronized with the time of the host device.

FIG. 1 is a schematic diagram of a time synchronization system according to an embodiment of the present invention. Please refer to FIG. 1 , the time synchronization system 100 includes a controller area network (CAN) system 10 and a host device 12 . The CAN system 10 includes a plurality of CAN devices 11(1) to 11(n). The CAN devices 11( 1 ) to 11(n) can be connected to each other through twisted pairs to communicate with each other.

Each of the CAN devices 11(1)-11(n) may include a CAN controller (eg, a microcontroller) and a CAN transceiver. The CAN controller is used to control the operation of the CAN device, and the CAN transceiver can be used to receive data packets from other CAN devices or send data packets to other CAN devices.

Each of the CAN devices 11(1)-11(n) may be connected to one or more Electronic Control Units (ECUs). In one embodiment, it is assumed that the time synchronization system 100 and the CAN system 10 are installed in an in-vehicle system. Therefore, the ECU may be a controller for controlling specific vehicle electronic components in this vehicle system. Furthermore, multiple ECUs can communicate with each other via the CAN system 10 (eg, CAN devices 11(1)-11(n)). However, in another embodiment, the time synchronization system 100 and the CAN system 10 may also be installed in other types of electronic systems, not limited to the vehicle-mounted system.

The host device 12 is coupled to the CAN system 10 . The host device 12 can be connected to and communicate with the first CAN device in the CAN system 10 via a communication protocol such as Universal Serial Bus (USB) or Ethernet. For example, host device 12 may be any type of computer device or computer host. For example, the host device 12 may include a central processing unit (CPU), or other programmable general-purpose or special-purpose microprocessors, digital signal processors (DSPs), programmable controllers, special Application Specific Integrated Circuits (ASIC), Programmable Logic Device (PLD) or other similar devices or combinations of these devices.

In one embodiment, the host device 12 may establish a time mapping relationship (also referred to as a time mapping relationship) between the first CAN device and the host device 12 in the test mode of the first CAN device. This time mapping relationship can be used to synchronize the clock of the host device 12 with the clock of the first CAN device.

In one embodiment, the test mode is also referred to as a loopback mode. When the first CAN device is in the test mode, if the first CAN device receives a packet (also referred to as a test packet) from the host device 12, the first CAN device can directly return the test packet to the host device 12 without This test packet is sent to the rest of the CAN devices in the CAN system 10 .

In one embodiment, the host device 12 may read CAN time information of at least one packet (also referred to as a data packet) from the first CAN device in the normal mode of the first CAN device. For example, when the first CAN device receives a data packet from the remaining CAN devices in the CAN system 10, the first CAN device can record the time at which it received the data packet (ie, CAN time information). In other words, the CAN time information of a data packet can reflect the time when the first CAN device received the data packet. The first CAN device can store the received data packet and related information (eg, packet ID, packet content and CAN time information) in its internal register. When the first CAN device is in the normal mode, the host device 12 can read the data packet and information related to the data packet (eg, the CAN time information) from the register of the first CAN device.

In one embodiment, the host device 12 may record the host time information of the data packet according to the time mapping relationship and the CAN time information of the data packet. The host time information refers to the time indicated by the clock of the host device 12 when the first CAN device receives a certain data packet. In other words, after reading the CAN time information of a data packet from the first CAN device, the host device 12 can convert the CAN time information of the data packet into when the first CAN device receives the data according to the time mapping relationship The time indicated by the clock of the host device 12 at this time (ie, the host time information) when the packet is being packaged.

In the following embodiments, the CAN device 11(1) is used as an example of the first CAN device. However, in another embodiment, the first CAN device may also refer to one or more of the CAN devices 11(2)˜11(n).

FIG. 2 is a schematic diagram of establishing a time mapping relationship between a first CAN device and a host device according to an embodiment of the present invention. Referring to FIGS. 1 and 2 , within the time range 21 , the host device 12 may set the CAN device 11 ( 1 ) to a test mode (also referred to as a first test mode). In the first test mode (ie, within the time range 21 ), the host device 12 may send a test packet (also referred to as a first test packet) PT( 1 ) to the CAN device 11 ( 1 ). Then, the host device 12 may record the host time information (also referred to as the first host time information) TP(1) of the test packet PT(1) and the CAN time information (also referred to as the first CAN time) of the test packet PT(1). Information) TC(1).

In one embodiment, when the test packet PT(1) is sent, the host device 12 may record the host time information T1(Tx) when the test packet PT(1) is sent. For example, the host time information T1(Tx) may reflect the time when the host device 12 sends the test packet PT(1). When the CAN device 11(1) receives the test packet PT(1), the CAN device 11(1) can record the CAN time information TC(1) of the test packet PT(1). For example, the CAN time information TC(1) may reflect the time when the CAN device 11(1) receives the test packet PT(1). When the host device 12 receives the test packet PT(1) returned by the CAN device 11(1), the host device 12 may record another host time information T1(Rx) of the test packet PT(1). For example, the host time information T1(Rx) may reflect the time when the host device 12 receives the test packet PT(1). The host device 12 may determine the host time information TP(1) according to the host time information T1(Tx) and T1(Rx). For example, the host time information TP(1) may be equal to (T1(Tx)+T1(Rx))/2. In one embodiment, the operation of recording the host time information TP(1) and the CAN time information TC(1) is similar to establishing a mapping relationship between the host time information TP(1) and the CAN time information TC(1).

After recording the host time information TP(1) and the CAN time information TC(1), within the time range 22, the host device 12 can control the CAN device 11(1) to switch from the first test mode to the normal mode. In the normal mode of the CAN device 11(1) (ie, within the time range 22), the host device 12 can read CAN time information of at least one data packet from the CAN device 11(1).

It should be noted that, in the embodiment of FIG. 2 , the CAN time information TC(k) of the data packet PN(k) is read as an example. The data packet PN(k) is a data packet temporarily stored in the register of the CAN device 11(1), and the CAN time information TC(k) can reflect the time when the CAN device 11(1) received the data packet PN(k) . The host device 12 may record the CAN time information TC(k) of the data packet PN(k). The number of data packets PN(k) can be one or more, which is not limited in the present invention.

After recording the CAN time information TC(k) of the data packet PN(k), within the time range 23, the host device 12 can set the CAN device 11(1) to the test mode (also referred to as the second test mode) again. In the second test mode (ie, within the time range 23), the host device 12 may send a test packet (also referred to as a second test packet) PT(2) to the CAN device 11(1). Then, the host device 12 may record the host time information (also referred to as the second host time information) TP(2) of the test packet PT(2) and the CAN time information (also referred to as the second CAN time) of the test packet PT(2). Information) TC(2).

In one embodiment, when the test packet PT(2) is sent, the host device 12 may record the host time information T2(Tx) when the test packet PT(2) is sent. For example, the host time information T2(Tx) may reflect the time when the host device 12 sends the test packet PT(2). When the CAN device 11(1) receives the test packet PT(2), the CAN device 11(1) can record the CAN time information TC(2) of the test packet PT(2). For example, the CAN time information TC(2) can reflect the time when the CAN device 11(1) receives the test packet PT(2). When the host device 12 receives the test packet PT(2) returned by the CAN device 11(1), the host device 12 can record another host time information T2(Rx) of the test packet PT(2). For example, the host time information T2(Rx) may reflect the time when the host device 12 receives the test packet PT(2). The host device 12 can determine the host time information TP(2) according to the host time information T2(Tx) and T2(Rx). For example, the host time information TP(2) may be equal to (T2(Tx)+T2(Rx))/2. In one embodiment, the operation of recording the host time information TP(2) and the CAN time information TC(2) is similar to establishing a mapping relationship between the host time information TP(2) and the CAN time information TC(2).

3 is a schematic diagram of recording host time information of a data packet according to a time mapping relationship and CAN time information according to an embodiment of the present invention. Referring to FIGS. 1 to 3 , the host device 12 can use the host time information TP( 1 ), the CAN time information TC( 1 ), the host time information TP( 2 ), the CAN time information TC( 2 ) and the data packet PN(k ) of the CAN time information TC(k) determines the host time information TP(k). The host time information TP(k) can reflect the time indicated by the clock of the host device 12 when the CAN device 11(1) receives the data packet PN(k).

In one embodiment, the host device 12 can convert the CAN time information TC(k) according to the host time information TP(1), the CAN time information TC(1), the host time information TP(2) and the CAN time information TC(2). ) maps to the host time information TP(k). In one embodiment, the host device 12 can obtain the offset time information of the CAN time information TC(k) compared to at least one of the CAN time information TC(1) and TC(2). Then, the host device 12 can obtain the host time information TP(k) according to the host time information TP(1), the host time information TP(2) and the offset time information.

In one embodiment, the host device 12 can obtain the difference values r(1) and r(2) according to the CAN time information TC(1), TC(2) and TC(k). The difference r(1) reflects the time difference between the CAN time information TC(1) and TC(k) (for example, r(1)=TC(k)−TC(1)). The difference r(2) reflects the time difference between the CAN time information TC(k) and TC(2) (eg r(2)=TC(2)−TC(k)). The difference r(1) and/or r(2) may be the offset time information. The host device 12 may use the ratio of the difference r(1) to r(2) (or the ratio of the difference r(1) to (r(1)+r(2))) to calculate the host time information TP(1) The host time information TP(k) is determined between TP(2).

It should be noted that there is a difference r(3) between the host time information TP(1) and the determined host time information TP(k), and the host time information TP(2) and the determined host time information TP( There is a difference r(4) between k). The difference r(3) reflects the time difference between the host time information TP(1) and TP(k) (eg, r(3)=TP(k)−TP(1)). The difference r(4) reflects the time difference between the host time information TP(k) and TP(2) (eg, r(4)=TP(2)-TP(k)). The ratio between the differences r(3) and r(4) may be the same (or substantially the same) as the ratio between the differences r(1) and r(2).

In one embodiment, the host device 12 can obtain the time difference Td between the host time information TP(1) and TP(2). The host device 12 may multiply the time difference Td by (r(1)/(r(1)+r(2))) to obtain the difference r(3). Then, the host device 12 may add the host time information TP(1) to the difference r(3) to obtain the host time information TP(k). It should be noted that the host device 12 can also obtain the host time information TP(k) through other logical operation methods, as long as the above specification of the numerical ratio is met.

In one embodiment, the host device 12 may display the obtained host time information TP(k) of the data packet PN(k) on the display of the host device 12 . In this way, the operator of the host device 12 can clearly know that the data packet PN(k) was sent to the CAN device 11 ( 1) Receive. In addition, the application program of the host device 12 can process the data packet PN(k) according to the synchronized host time information TP(k).

FIG. 4 is a flowchart of a time synchronization method according to an embodiment of the present invention. Referring to FIG. 4 , in step S401 , in the test mode of the CAN device in the CAN system, a time mapping relationship between the CAN device and the host device is established. In step S402, in the normal mode of the CAN device, read CAN time information of at least one data packet from the CAN device. In step S403, the host time information of the at least one data packet is recorded according to the time mapping relationship and the CAN time information.

FIG. 5 is a flowchart of a time synchronization method according to an embodiment of the present invention. Referring to FIG. 5 , in step S501 , the CAN device is set to a test mode. In step S502, a receiver thread is established in the CAN device. In step S503, the test packet is sent from the host device and the time when the packet is sent is recorded. In step S504, the receiver of the host device schedules to receive the test packet returned from the CAN device and records the time when the host device and the CAN device respectively receive the test packet. In step S505, the host time information of the test packet and the CAN time information of the test packet are recorded according to the times recorded in steps S503 and S504. For example, the process and related operations of FIG. 5 may be performed within time ranges 21 and 23 in FIG. 2 .

FIG. 6 is a flowchart of a time synchronization method according to an embodiment of the present invention. Referring to FIG. 6, in step S601, the CAN device is set to the normal mode. In step S602, a record file is created. In step S603, at least one data packet and CAN information related to the at least one data packet are read from the CAN device, and the information is recorded in the log file. For example, the flow and related operations of FIG. 6 may be performed within the time frame 22 of FIG. 2 .

FIG. 7 is a flowchart of a time synchronization method according to an embodiment of the present invention. Referring to FIG. 7, in step S701, the record file is opened. In step S702, the CAN information of the at least one data packet is read from the record file, including CAN time information. In step S703, the host time information of the at least one data packet is recorded according to the established time mapping relationship and the CAN information. For example, for step S703 in FIG. 7 , reference may be made to the description of the embodiment in FIG. 3 , and details are not repeated here.

However, each step in FIG. 4 to FIG. 7 has been described in detail as above, and will not be repeated here. It should be noted that each step in FIG. 4 to FIG. 7 can be implemented as a plurality of codes or circuits, which is not limited by the present invention. In addition, the methods of FIG. 4 to FIG. 7 can be used in conjunction with the above exemplary embodiments, and can also be used alone, which is not limited by the present invention.

To sum up, in the test mode of the CAN device, the time mapping relationship between the CAN device and the host device can be established. In addition, in the normal mode of the CAN device, CAN time information of at least one data packet can be read from the CAN device. According to the time mapping relationship and the CAN time information, the host time information of the at least one data packet can be recorded, so that the reception time of the at least one data packet is synchronized with the time of the host device. In this way, the problems caused by the time synchronization between the clock of the CAN device and the clock of the host device in the past can be effectively improved (for example, the application of the host device misjudged the receiving time and/or sequence of the data packets).

100: Time Synchronization System 10: Controller Area Network (CAN) system 11(1)~11(n): CAN device 12: Host device 21, 22, 23: time frame PT(1), PT(2): Test packets PN(k): data packet TP(1), TP(2), TP(k): host time information TC(1), TC(2), TC(k): CAN time information r(1), r(2), r(3), r(4): difference S401~S403, S501~S505, S601~S603, S701~S703: Steps

FIG. 1 is a schematic diagram of a time synchronization system according to an embodiment of the present invention. FIG. 2 is a schematic diagram of establishing a time mapping relationship between a first CAN device and a host device according to an embodiment of the present invention. 3 is a schematic diagram of recording host time information of a data packet according to a time mapping relationship and CAN time information according to an embodiment of the present invention. FIG. 4 is a flowchart of a time synchronization method according to an embodiment of the present invention. FIG. 5 is a flowchart of a time synchronization method according to an embodiment of the present invention. FIG. 6 is a flowchart of a time synchronization method according to an embodiment of the present invention. FIG. 7 is a flowchart of a time synchronization method according to an embodiment of the present invention.

S401~S403: Steps

Claims (8)

A time synchronization method for a controller area network (Controller Area Network, CAN) system, the time synchronization method comprising: setting a CAN device in the CAN system to a first test mode; In the mode, send a first test packet to the CAN device and record a first host time information of the first test packet and a first CAN time information of the first test packet; control the CAN device from the first test The mode is switched to a normal mode; in the normal mode of the CAN device, the CAN time information of at least one data packet is read from the CAN device; after reading the CAN time information of the at least one data packet from the CAN device , set the CAN device to a second test mode; in the second test mode, send a second test packet to the CAN device and record a second host time information of the second test packet and the second test a second CAN time information of the packet; and according to the first CAN time information, the first host time information, the second CAN time information, the second host time information and the CAN time information of the at least one data packet, A host time information of the at least one data packet is recorded. The time synchronization method of claim 1, wherein the step of recording the first host time information of the first test packet comprises: according to the time when the host device sends the first test packet and the time when the host device receives the first test packet via The timing of the CAN device sending the first test packet back to the host device is determined The first host time information. The time synchronization method as described in claim 1, wherein according to the first CAN time information, the first host time information, the second CAN time information, the second host time information and the at least one data packet For the CAN time information, the step of recording the host time information of the at least one data packet includes: according to the first host time information, the first CAN time information, the second host time information and the second CAN time information, The CAN time information of the at least one data packet is mapped to the host time information of the at least one data packet. The time synchronization method according to claim 3, wherein the at least one data packet is packaged according to the first host time information, the first CAN time information, the second host time information and the second CAN time information The step of mapping the CAN time information to the host time information of the at least one data packet includes: obtaining an offset of the CAN time information compared to at least one of the first CAN time information and the second CAN time information and obtaining the host time information of the at least one data packet according to the first host time information, the second host time information and the offset time information. A time synchronization system, comprising: a host device; and at least one CAN device, including a first CAN device and coupled to the host device, wherein the host device is used for: setting the first CAN device as a first test model; In the first test mode, send a first test packet to the first CAN device and record a first host time information of the first test packet and a first CAN time information of the first test packet; control the The first CAN device is switched from the first test mode to a normal mode; in the normal mode of the first CAN device, the CAN time information of at least one data packet is read from the first CAN device; After the CAN device reads the CAN time information of the at least one data packet, the first CAN device is set to a second test mode; in the second test mode, a second test packet is sent to the first CAN device and record a second host time information of the second test packet and a second CAN time information of the second test packet; and according to the first CAN time information, the first host time information, the second CAN time information , the second host time information and the CAN time information of the at least one data packet, record a host time information of the at least one data packet. The time synchronization system according to claim 5, wherein the operation of the host device recording the first host time information of the first test packet includes: according to the time when the host device sends the first test packet and the host The time at which the device receives the first test packet sent back to the host device via the first CAN device determines the first host time information. The time synchronization system of claim 5, wherein the host device is based on the first CAN time information, the first host time information, the second CAN time information, the second host time information and the CAN time information of the at least one data packet, the operation of recording the host time information of the at least one data packet includes: according to the first host time information, the first CAN time information, the second host time information and the second CAN time information, and the CAN time information of the at least one data packet is mapped to the host time information of the at least one data packet. The time synchronization system of claim 7, wherein the host device according to the first host time information, the first CAN time information, the second host time information and the second CAN time information, the at least The operation of mapping the CAN time information of a data packet to the host time information of the at least one data packet includes: obtaining the CAN time information compared to at least one of the first CAN time information and the second CAN time information and obtain the host time information of the at least one data packet according to the first host time information, the second host time information and the offset time information.

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