CAN interface overview

• The CAN bus provides one point of entry to communicate with all network nodes enabling central data logging and diagnostics purposes.
• CAN frames are prioritized by message ID. So that the high priority message ID gets control of the bus arbitration. Bitwise arbitration helps manage CAN bus access and avoid collisions through ID-based priority.
• The CAN bus has two logical states during operation:

  • Recessive level, where the recessive bus state is equivalent to logical high and called as the Idle state.
  • Dominant level, where the dominant bus state is equivalent to logical low.

• Any node can transmit data at any time. There is no primary-secondary node concept in case of CAN communication.
• CAN nodes are synchronized using bit-synchronization where each bit time is divided into four segments of time quanta.
• The CAN protocol ensures error handling and detecting CAN errors including CRC and ACK.

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CAN features

• Priority-based bus access.
• Nondestructive bitwise-based arbitration.
• Broadcast through all-frame transfer.
• Multicast frame transfer by acceptance filtering.
• Error detection and error signaling.
• Automatic deactivation of faulty nodes by identifying the failure nodes.

• DMA mode: CAN frames are moved from RX FIFO to system memory through DMA with minimal CPU load.
• Polling mode: CPU periodically checks RX FIFO for new frames and processes them.
• Interrupt mode: When a frame is received, the CPU is notified using an interrupt and it reads the data from the RX FIFO.

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CAN architecture

• IQ-9075
• IQ-8275

CAN0The Dragonwing IQ-9075 EVK supports eight CAN channels. The Dragonwing IQ-9075 EVK supports the CAN0 connection with the TLE9255WLC transceiver. The following figure shows connection between the CAN0 channels and the TLE9255WLC transceiver that supports the baud rate up to 5 MBPS

CAN1/CAN2/CAN3/CAN4/CAN5/CAN6/CAN7The Dragonwing IQ-9075 EVK supports the CAN1/CAN2/CAN3/CAN4/CAN5/CAN6/CAN7 connection with the ADM3058EBRIZ-RL transceiver. The following figure shows the connection between the CAN1/CAN2/CAN3/CAN4/CAN5/CAN6/CAN7 channels and the ADM3058EBRIZ-RL transceiver that supports the baud rate up to 12 MBPS.

CAN0The Dragonwing IQ-8275 EVK supports four CAN channels. The Dragonwing IQ-8275 EVK supports the CAN0 connection with the TLE9255WLC transceiver. The following figure shows connection between the CAN0 channel and the TLE9255WLC transceiver that supports the baud rate up to 5 MBPS:

CAN1/CAN2/CAN3The Dragonwing IQ-8275 EVK supports the CAN1/CAN2/CAN3 connection with the ADM3058EBRIZ-RL transceiver. The following figure shows the connection between the CAN1/CAN2 channels and the ADM3058EBRIZ-RL transceiver that supports the baud rate up to 12 MBPS.

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CAN files

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Verify CAN interface

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Customize CAN interface

1. Add a mapping array for the new transceiver:

   CAN_DATA static uint8_t Can_Tle9255_Map[CAN_MTTCAN_MAX_CNT] = {0};
   

2. Map the appropriate CAN channel (example for CAN0):

   if (chip_family == CHIPINFO_FAMILY_LEMANSAU)
   {
   Can_Tcan1146_Map[0] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[1] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[2] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[3] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[4] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[5] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[6] = CAN_TCAN_INVALID;
   Can_Tcan1146_Map[7] = CAN_TCAN_INVALID;
   
   Can_Tcan1044_Map[0] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[1] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[2] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[3] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[4] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[5] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[6] = CAN_TCAN_INVALID;
   Can_Tcan1044_Map[7] = CAN_TCAN_INVALID;
   
   Can_Tle9255_Map[0] = CAN_TCAN1146_CHAN_0;
   Can_Tle9255_Map[1] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[2] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[3] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[4] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[5] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[6] = CAN_TCAN_INVALID;
   Can_Tle9255_Map[7] = CAN_TCAN_INVALID;
   }
   

CanTrcv_Tle9255_Init();