RPI - CANOpen

Links

https://www.autopi.io/blog/canopen-simple-introduction-explained/

https://copperhilltech.com/cangineberry-canopen-module-for-raspberry-pi/

https://www.seeedstudio.com/CAN-BUS-FD-HAT-for-Raspberry-Pi-p-4742.html?gad=1&gclid=Cj0KCQjwk96lBhDHARIsAEKO4xYAmLdGQNoTgtlQiTcZrmM7NoMeBFUGK7oMgsC-L3k_4WfpV43_WLYaAnTaEALw_wcB

https://www.autopi.io/blog/raspberry-pi-can-bus-explained/#:~:text=The%20Raspberry%20Pi%20hardware%20does,the%20CAN%20Bus%20(Raspbian).

https://copperhilltech.com/search.php?search_query=pican3&Search=

Config

Running a Seeed mcp2518fd based board with 2 can bus.

after boot, should see the following:

$ dmesg | grep can

[   11.115212] mcp251xfd spi0.1 can0: MCP2518FD rev0.0 (-RX_INT -PLL -MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD o:40.00MHz c:40.00MHz m:20.00MHz rs:17.00MHz es:16.66MHz rf:17.00MHz ef:16.66MHz) successfully initialized.

[   11.217854] mcp251xfd spi0.0 can1: MCP2518FD rev0.0 (-RX_INT -PLL -MAB_NO_WARN +CRC_REG +CRC_RX +CRC_TX +ECC -HD o:40.00MHz c:40.00MHz m:20.00MHz rs:17.00MHz es:16.66MHz rf:17.00MHz ef:16.66MHz) successfully initialized.

Now set the interface "up":

$ sudo ip link set can0 up type can bitrate 100000

$ sudo ip link set can1 up type can bitrate 100000

Now testing the link with can0 connected to can1.

$ candump can0

$ cansend can1 111#ff

CANopen message structure

The CANopen frame contains the arbitration field (12 bits) and data fields (8 bytes)

CANopen frame sequence

The arbitration field contains an 11 bit identifier (COB-ID) which describes the message types. The cob-id defines the message priority, 0 is the highest, 0x7ff is the lowest. It also contains a 1 bit RTR (remote transmit request). This requests a response from the target device.

Arbitration Fields

NMT messages have cob-id of 0 (zero). These messages request the communication state of the node-id (data byte 2) be set to the designated state in data byte 1.

NMT message structure