KR20070117264A - Flexray-can gateway structure and message mapping method - Google Patents

Abstract

A FlexRay-CAN(Controller Area Network) gateway structure and a message mapping method are provided to reduce an influence of an overhead and an increase in a delay time caused by conversion of a transmission method between a CAN and a FlexRay each having a different transmission method. A message mapping table(270) stores and manages information about several signals included in CAN and FlexRay messages. A message filter(220) filters the CAN message based on the message mapping table(270), and divides and transmits it via an arbiter(230). A time-division-based queue(260) transmits a signal transmitted by the message filter(220) to a fixed slot(310) of a FlexRay network(300) at every time slot. A priority-based queue(250) attempts transmission of the signal which has been transmitted by the message filter(220) at every cycle, and when its priority level comes, the priority-based queue(250) transmits the signal to a variable slot(320) of the FlexRay network(300). If its priority level does not come, the priority-based queue(250) waits. A message filter(222) filters the FlexRay message based on the message mapping table(270) and transmits it. A priority-based queue(252) stores the signal which has been transmitted by the message filter(222) in a queue with determined CAN IDs, and when signals are all stored in the IDs, the priority-based queue(252) transmits them to a CAN network(100) via the arbiter(232) according to each priority level. A controller(210) controls each element and performs message conversion and transmission based on the message mapping table(270).

Description

Flexray-CAN Gateway Structure and Message Mapping Method

1A and 1B are frame diagrams of a general CAN message and a FlexRay message,

2 is a structural diagram of a FlexRay-CAN gateway according to the present invention;

3 and 4 are flowcharts illustrating a process of transmitting data from the CAN network to the FlexRay network through the gateway shown in FIG. 2;

5 is a flow chart for transmitting data from the FlexRay network to the CAN network through the gateway shown in FIG.

6 and 7 is a flow chart of the message mapping by policy from the CAN network to the FlexRay network according to the present invention,

8 is a flow chart of message mapping from a FlexRay network to a CAN network in accordance with the present invention.

<Description of the symbols for the main parts of the drawings>

100: CAN network 200: gateway

210: gateway controller 220,222: message filter

230,232: Arbitr 240,242: Gateway buffer

250,252: priority based queue 260: time division based queue

270: Message Mapping Table 300: FlexRay Network

310: fixed slot 320: variable slot

The present invention relates to a FlexRay-CAN gateway structure and a message mapping method, and more particularly, the communication from the FlexRay to CAN is priority-based queuing in a queue management scheme for the FlexRay-CAN gateway. Performs queuing, and communication from CAN to FlexRay performs priority and time division based queuing.

CAN (Controller Area Network) communication is a method of transmitting data having a size of 0 to 8 bytes to the network based on the priority of the ID using an ID for classifying the data according to the priority.

At this time, the network topology has a bus shape, and in order for several nodes in a network to communicate without error, the network topology is adjusted to transmit only one node having the highest priority.

The CAN communication is capable of communication at a baud rate of 500 kbps, and the bit fields in the CAN message frame 10 are respectively represented by a SOF (Start of Frame) field 11 and an Arbitration field (as shown in FIG. 1A). 12), control field 13, data field 14, cyclic redundancy check (CRC) field 15, acknowledgment (ACK) field 16, end of frame (EOF) field 17, and the like.

At this time, each field is assigned a bit number according to a predetermined scheme.

For example, the data to be exchanged between each controller and the CAN system is loaded into a data field 14 having a size of 0 to 8 bytes, and 16 bits are allocated to the CRC field 15 for cyclic redundancy check (CRC). It is a system.

In addition, the structure of the internal data memory of each CAN controller connected on the CAN bus has 15 CAN data message objects consisting of 8 bytes, and each message object has a different identifier (ID) for classifying data according to priority. Has

However, CAN network has been replaced by FlexRay, the next-generation automotive network, due to problems such as bandwidth limitation at 500kbps, lack of basic support of backup channel and increased delay of low priority message due to multiple access based on priority. It should be.

On the other hand, FlexRay, a communication protocol currently under development, is defined to use a time division multiple access (TDMA) scheme for static segments and a flexible time-division multiple-access (FTDMA) arrangement for dynamic segments.

The FlexRay transmits data having a size of 0 to 254 bytes to the network in a static slot scheme and a dynamic slot scheme based on priorities so that a specific node sends only a time allocated to the specific node. will be.

The FlexRay supports simultaneous time division and priority based multiple access schemes for flexible network configuration, and the network topology has bus and star shapes.

In addition, the transmission speed is up to 10Mbps, it is possible to improve the reliability of the communication by setting a backup channel.

The frame 20 of the FlexRay is composed of a header segment 20a, a payload segment 20b, a trailer segment 20c and a header segment 20a as shown in FIG. 1B. ) Is composed of an indicator 21, a frame ID field 22, a payload length field 23, a header CRC field 24, and a cycle count field 25.

The payload segment 20b is composed of a plurality of data fields 26a, 26b, ..., 26n, and the trailer segment 20c is composed of three CRC fields 27a, 27b, 27c, with a constant scheme for each field. The number of bits is assigned accordingly.

However, in the case of flexlay, there is a problem in that expensive equipment is used because the equipment is not yet generalized.

Therefore, the overhead of the conversion between transmission method between CAN and FlexRay, which is a gateway to help construct a hybrid network by enabling communication between the devices for CAN and FlexRay, which are already spread and widely used. In order to reduce the effects of delays and increased latency, a message mapping method is needed.

The present invention has been made to solve the above-mentioned problems, to enable the communication between the equipment for CAN and the equipment for flex-lay to configure a hybrid network, the transmission method between CAN and FlexRay different transmission methods The objective is to provide a FlexRay-CAN gateway architecture and a message mapping method that can reduce the effects of overhead and latency.

According to an embodiment of the present invention, a FlexRay-CAN gateway structure includes a message mapping table for storing and managing information on a plurality of signals included in a CAN and a FlexRay message, and the CAN message. A message filter for filtering based on a message mapping table, divided and transmitted through an arbiter, a time division based queue for transmitting a signal transmitted from the message filter to a fixed slot of a FlexRay network at a predetermined time slot, and transmitting from the message filter A priority-based queue which attempts to transmit a signal every cycle and transmits it to a variable slot of a FlexRay network if its priority is applicable, and waits if its priority is not applicable, and stores the FlexRay message in a message mapping table. Message filters that filter and send based on And storing the signals transmitted from the message filter in a queue having a predetermined CAN ID, and when the signals to be loaded on each ID are placed on the queue, the priority-based queues and the respective transmissions are transmitted to the CAN network through the arbiter according to the priority. It includes a controller that controls the component and performs message translation and transmission based on the message mapping table.

In addition, the message mapping method between the flash-CAN according to an embodiment of the present invention, the message mapping according to the bandwidth maximization policy when the message generated in the CAN network to the FlexRay network through the FlexRay-CAN gateway,

Determining, at the gateway, whether a message occurring in a CAN network is periodic or aperiodic, comparing T _C with 64T _F when a CAN message occurs periodically, and T _C <64T _F in the comparing step Assigning int (64 / int (64T _F / T _C )) + i th cycle to the fixed slot 310 of the flexlay network 300 and if the CAN message occurs aperiodically or If T _C <64T _F , the first priority is assigned to the variable slot.

Hereinafter, the configuration and operation of the present invention will be described with reference to the accompanying drawings.

2 is a structural diagram of a FlexRay-CAN gateway according to the present invention.

As shown in FIG. 2, the gateway 200 according to the present invention includes a gateway controller 210, message filters 220 and 222, arbiters 230 and 232, gateway buffers 240 and 242, priority based queues 250 and 252, and time division based queues. 260 and a message mapping table 270.

The gateway controller 210 performs message conversion and transmission based on the message mapping table 270.

The transmitted CAN and FlexRay messages contain several signals, each of which is unique throughout the CAN and FlexRay networks 100 and 300.

The message mapping table 270 stores and manages information of this signal, and each signal has a signal name, a CAN ID, a CAN start bit, a length, a period, a FlexRay ID, a FlexRay start bit, and a FlexRay. Contains cycle information.

The gateway buffer 240 receives and temporarily stores a signal of a message transmitted from the CAN network 100.

The message filter 220 decomposes the signal temporarily stored in the gateway buffer 240 based on the message mapping table 270 to the time division based queue 260 or the priority based queue 250 through the arbiter 230. Send in divided.

The time division based queue 260 transmits a signal to a fixed slot 310 of the flexlay network 300 every predetermined time slot, and the priority based queue 250 attempts to transmit every cycle so that its priority is increased. If applicable, it transmits to the variable slot 320 of the FlexRay network and waits if its priority does not apply.

The gateway buffer 242 temporarily receives and receives a signal of a message transmitted from the flexlay network 300.

The message filter 222 decomposes the signal temporarily stored in the gateway buffer 242 based on the message mapping table 270 and transmits the decomposed signal to the priority based queue 252.

The priority-based queue 252 stores the decomposed signal in a queue having a predetermined CAN ID, and if all signals to be loaded on each ID are loaded, the CAN network is first transmitted through the arbiter 232 from the lower ID according to the priority. Send to 100.

Here, the low ID means having a high priority, and the ID having the highest priority among the CAN IDs 340, 230, 550, and 551 shown in FIG. 2 is 230.

The gateway controller 210 controls each of the above components to perform message conversion and transmission between the CAN network 100 and the flexlay network 300.

3 and 4 are flowcharts illustrating a process of transmitting data from the CAN network to the FlexRay network through the gateway shown in FIG. 2, and FIG. 3 is a flow chart when sending data to the fixed slot 310 of the FlexRay network. .

The gateway buffer 240 receives a signal of a message transmitted from the CAN network 100 to the fixed slot 310 of the flexlay network 300 (S302).

The message filter 220 filters the signals according to the management values of the message mapping table for all the signals of the received message and transmits the CAN signal data to the FlexRay fixed queue (Flexlay ID, FlexRay cycle) of the time division based queue 260. Copy (S304).

The time-division based queue 260 determines whether there is CAN signal data to be sent in the current cycle (S306), and if there is CAN signal data to be sent, transmits the CAN signal data to the fixed slot 320 of the FlexRay network 300 by corresponding time-division. The base queue 260 is initialized (S308), and if there is no CAN signal data to be sent, the process returns to step S302 and receives a signal of a message.

 4 is a flow chart when data is sent to the variable slot 320 of the FlexRay network.

The gateway buffer 240 receives a signal of a message transmitted from the CAN network 100 to the variable slot 320 of the flexlay network 300 (S402).

The message filter 220 filters the signal according to the management value of the message mapping table 270 and determines whether there is a variable slot ID in the queue entry of the priority-based queue 250 (S404). The data is copied to the corresponding queue entry (S406).

If there is no variable slot ID, a new cue entry corresponding to the ID is copied (S405), and then CAN signal data is copied to the corresponding cue entry (S406).

Priority-based queue 250 determines whether the number of signals in the queue entry is full through the above steps (S408), if it is full, the FlexRay starting from the CAN signal data having the highest ID among the transmittable queue entries The queue entry is deleted by transmitting to the variable slot 320 of the network 300 (S410).

When the number of signals does not reach the queue entry in step S408, the process returns to step S402 to perform a signal signal.

FIG. 5 is a flowchart for transmitting data from the FlexRay network to the CAN network through the gateway shown in FIG. 2.

The gateway buffer 242 receives a signal of a message transmitted from the flexlay network 300 to the CAN network 100 (S502).

The message filter 222 filters the signal according to the management value of the message mapping table 270 and determines whether there is a CAN ID in the queue entry of the priority-based queue 252 (S504). Copy the FlexRay signal data received from the queue entry (S506).

If the CAN ID does not exist, after generating a new cue entry corresponding to the CAN ID (S505), the FlexRay signal data is copied to the corresponding cue entry (S506).

The priority-based queue 252 determines whether the number of signals in the queue entry is full through the above-described steps (S508), and if it is full, starting from the FlexRay signal data having the ID having the highest priority among the queue entries that can be transmitted. The queue entry is deleted by transmitting to the network (S510).

When the number of signals does not reach the queue entry in step S508, the flow returns to step S502 to receive a signal of a message.

On the other hand, the message mapping policy is applied to signals to be transmitted from the CAN network 100 to the FlexRay network 200 that supports priority-based and time-division based communication at the same time. Two types of minimization policies can be defined.

First, the bandwidth maximization policy does not allocate a static slot when sending to the FlexRay 300 for a CAN message whose transmission cycle is not constant or difficult to assign. It is a method using.

In this case, there is an advantage that it is possible to allocate additional messages to the idle bandwidth by using the bandwidth efficiently, but there is a problem that the transmission delay time can be increased by priority.

The following delay minimization policy allocates the FlexRay fixed slot 310 to as many types of CAN messages as possible, which may cause a problem that bandwidth consumption is increased while the delay time of the message is guaranteed to a predetermined value.

Accordingly, the message correspondence of the CAN network 100 to the flexlay network 300 is classified according to the priority, the occurrence cycle characteristics, and the policy of the message as shown in Table 1, and the fixed slot 310 of the X-ray network 300 or the like. The variable slot 320 is allocated.

In this case, the method of allocating a periodic message to a specific cycle of a fixed slot is as follows.

First, if the cycle of the message occurring in the CAN network 100 is T _C , and one cycle period of the flexlay network 300 is T _F , and T _C <64T _F , the corresponding CAN in the flexlay network 300 is The period P of the message is given by Equation 1 or 2 according to the message mapping policy.

When undersampling (a method of calculating one or less samplings per pixel) to maximize bandwidth, P becomes Equation 1.

And when oversampling (oversampling) in order to minimize the delay time P is represented by equation (2).

번째 사이클이 할당된다.If you send from the i cycle

Cycle is allocated.

If T _C > 64T _F , the period P allocated to the fixed slot 310 is fixed to 64, the maximum value of the flexlay cycle.

6 and 7 are message mapping flowcharts for each policy from the CAN network to the FlexRay network according to the present invention. FIG. 6 is a mapping flowchart according to the bandwidth maximization policy, and FIG. 7 is a mapping flowchart according to the latency minimization policy.

In the mapping flowchart according to the bandwidth maximization policy of FIG. 6, the gateway 200 determines whether a message generated in the CAN network 100 is periodic or aperiodic (S602), and when a CAN message occurs aperiodically, first of all. The higher priority is allocated to the variable slot 310 (S608).

In the case where the CAN message occurs periodically, T _C is compared with 64T _F (S604), and if T _C <64T _F, then int (64 / int (64T _F / T _C )) + i th when transmitting from the i th cycle The cycle is allocated to the fixed slot 310 (S606).

The T _C or T is _C <64T _F as compared to 64T _F, starting with priority to the high priority is assigned to the variable slot (320) (S608).

In the mapping flowchart according to the delay minimization policy of FIG. 7, it is determined whether the message generated in the CAN network is periodic or aperiodic (S702). 320) (S708).

When _C CAN occurs periodically, T _C is compared with 64T _F (S704). If T _C <64T _F, then int (64 / int (64T _F / T _C ) +1) + The i th cycle is allocated to the fixed slot 310 (S706).

When T _C is not T _C > 64T _F compared to 64 T _F , the T _C is allocated to the variable slot from the highest priority (S708).

As such, the message mapping from the gateway 200 to the CAN network 100 to the flexlay network 300 is classified according to the generation cycle and the policy and allocated to the fixed slot 310 or the variable slot 320 of the flexlay network. The increase in transmission latency, which is a problem of the maximization policy, and the increase in bandwidth usage, which is a problem of the delay minimization policy, can be prevented.

The message mapping of the FlexRay network 200 to the CAN network 100 defines a threshold of the CAN ID so that the messages of the variable slot 320 sequentially map lower than the threshold, and the fixed slot 310 Messages are mapped sequentially higher than the threshold value, and the flowchart illustrating this case is shown in FIG. 8.

8 is a flow chart of message mapping from a FlexRay network to a CAN network in accordance with the present invention.

First, the gateway 200 defines a threshold value of the CAN ID (S802), and is the message transmitted from the flexlay network 300 to the CAN network 100 a fixed slot 310 message or a variable slot 320 message? (S804), in the case of a fixed slot message, the priority of the CAN ID higher than the threshold value is higher in order (for example, when the threshold value is defined as 100, CAN ID 101, 102, 103, ...) and assigns it (S806). In the case of a variable slot message rather than a fixed slot message, the priority of the CAN ID lower than the threshold value is allocated in order of low priority (ie, CAN ID 99, 98, 97, ...) (S808).

As described above, according to the present invention, it is possible to configure a hybrid network by enabling communication between the equipment for CAN and the equipment for the FlexRay, and the over-due due to the conversion of the transmission scheme between the CAN and the FlexRay with different transmission methods. The effects of increased head and latency can be reduced.

Claims (6)

A message mapping table 370 for storing and managing information on a plurality of signals included in CAN and FlexRay messages; A message filter 220 for filtering the CAN message based on a message mapping table and transmitting the divided CAN messages through an arbiter 230; A time division based queue 260 for transmitting the signal transmitted from the message filter 220 to the fixed slot 310 of the flexlay network 300 at a predetermined time slot; Attempts to transmit the signal transmitted by the message filter 220 every cycle, and transmits the signal to the variable slot 320 of the FlexRay network 300 if its priority is applicable and waits if its priority is not applicable. Priority-based queue 250; A message filter 222 for filtering and transmitting the FlexRay message based on a message mapping table 270; The signal transmitted from the message filter 222 is stored in a queue having a predetermined CAN ID, and when a signal to be loaded on each ID is placed on the queue, the signal is transmitted to the CAN network 100 through the arbiter 232 according to priority. Priority-based queue 252; And And a controller (210) for controlling each component and performing message conversion and transmission based on the message mapping table (270). The method of claim 1, And the signal is uniquely present throughout the CAN and FlexRay networks (100,300). The method according to claim 1 or 2, The information of the signal stored in the message mapping table 270 may include a signal name, a CAN ID, a CAN start bit, a length, a period, a FlexRay ID, a FlexRay start bit, and a FlexRay cycle information. FlexRay-CAN gateway structure. When a message originating from a CAN network is transmitted through the FlexRay-CANN gateway to the FlexRay network, the message mapping according to the bandwidth maximization policy, Determining, at the gateway 200, whether a message occurring in the CAN network 100 is periodic or aperiodic; Comparing T _C (generating CAN message) to 64 T _F (one cycle period of FlexRay network) when CAN message occurs periodically, Assigning an int (64 / int (64T _F / T _C )) + i th cycle to the fixed slot 310 of the flexlay network 300 when T _C <64T _F in the comparing step; When the CAN message occurs aperiodically or when the T _C <64T _F , the step of assigning to the variable slot (320) from the higher priority, characterized in that the message mapping method between the Flex-CAN. When a message originating from a CAN network is transmitted through the FlexRay-CAN gateway to the FlexRay network, the message mapping according to the latency minimization policy is Determining, at the gateway 200, whether a message occurring in the CAN network 100 is periodic or aperiodic; Comparing T _C with 64 T _F when a CAN message occurs periodically; Allocating int (64 / int (64T _F / T _C ) +1) + i th cycle to the fixed slot 310 of the flexlay network 300 when T _C <64T _F in the comparing step; If the CAN message occurs aperiodic or when the T _C <64T _F , the first priority is assigned to the variable slot 320, characterized in that the step of mapping the message between the Flex-CAN. When a message originating from the FlexRay network is sent to the CAN network via the FlexRay-CANN gateway, the message mapping is Defining a threshold value of the CAN ID in the gateway 200; Determining whether the flexlay message is a fixed slot 310 message or a variable slot 320 message; Assigning to the CAN network 100 in the order of the priority of the CAN ID higher than the threshold value in the case of the fixed slot message; and In the case of the variable slot message, the message mapping method between the FlexRay and the CAN, characterized in that the step of assigning to the CAN network (100) in the order of lower priority of the CAN ID lower than the threshold value.

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