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CAN Listener.md

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CAN Listener

About

This test rig receives messages from a CAN bus and prints them to the UART3 serial port. Receiving is implemented using RTCAN and is limited to a predefined set of messages in config.h.

Configuration

This test rig is set up through the configuration header. The following settings are available:

Macro Name Values Description
CONFIG_ENABLE_CAN_LISTENER 1 or 0 Enables/disables the test rig
CONFIG_LISTEN_TO_CAN1 1 or 0 Monitors and prints messages received on CAN1
CONFIG_LISTEN_TO_CAN2 1 or 0 Monitors and prints messages received on CAN2
CONFIG_CAN1_NAME C string Custom name to identify CAN1 bus
CONFIG_CAN2_NAME C string Custom name to identify CAN2 bus
CONFIG_CAN1_LISTEN_IDS Array of uint32_t List of CAN IDs to listen for on CAN1
CONFIG_CAN2_LISTEN_IDS Array of uint32_t List of CAN IDs to listen for on CAN2

Hardware Setup

Setup:

  1. Connect the CAN1 or CAN2 Tx and Rx pins of the STM32 to a CAN transceiver.
  2. Connect the CAN transceiver to the CAN bus to be listened to.
  3. Build and flash the code.
  4. Connect the STM32 to your computer using a micro USB cable and open a serial monitor (PuTTY, screen, minicom, etc) at 115200 baud.
  5. Reset the STM32.

Info about received messages is sent to UART3 and looks like:

Bus:     CAN1
Tick:    75030
ID:      0x100
Length:  8
Data:    0xff03000000000000

Make sure that:

  • Devices on the CAN bus which you want to listen to operate at 500kbps (in line with everything CAN on the car).
  • The serial connection is configured to 115200 baud, no parity, 1 stop bit.

Limitations

  • It is likely that because of the serial printing, if the CAN bus utilisation gets really high or messages arrive very close to each other, the listener won't be able to keep up.
  • If you want to actually monitor and log CAN bus messages during testing, use the L120 datalogger.