Rockpi4/use-rs485-can-hat-on-rock-pi-4

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    ROCK Pi 4 > use-rs485-can-hat-on-rock-pi-4

Introduction

This guide tells The SPI interface of the development board is converted into can interface through RS485 CAN HAT interface

Upgrade kernel or flash system image if needed

I use the following image to test can here. https://dl.radxa.com/rockpi4/images/debian/rockpi4b_debian_buster_xfce4_arm64_20210608_1321-gpt.img.gz and install it to ROCK Pi 4B.

    # ls /usr/lib/modules/`uname -r`/kernel/drivers/net/can/spi/mcp251x.ko
    /usr/lib/modules/4.4.154-112-rockchip-gfdb18c8bab17/kernel/drivers/net/can/spi/mcp251x.ko

You need to update APT first

    go to  https://wiki.radxa.com/Rockpi4/radxa-apt

Download code sample

At board terminal：

   $ sudo apt-get install p7zip-full
   $ wget http://www.waveshare.net/w/upload/d/de/RS485_CAN_HAT_Code.7z
   $ 7z x RS485_CAN_HAT_Code.7z -r -o./RS485_CAN_HAT_Code
   $ sudo chmod 777 -R RS485_CAN_HAT_Code/

Connection mode

   H-H
   L-L

Block reception

• open the board terminal, and run:

  $cd RS485_CAN_HAT_Code/CAN/wiringPi/receive/
  $make clean
  $make
  $sudo ./can_receive

Can see

   root@rockpi4b:/home/rock# ./can_receive
   this is a can receive demo

Send

• open the another board terminal and run:

    $cd RS485_CAN_HAT_Code/CAN/wiringPi/send/
    $make clean
    $make
    $sudo ./can_send

Can see

    # ./can_receive
    this is a can receive demo
    can_id = 0x123
    can_dlc = 8
    data[0] = 1
    data[1] = 2
    data[2] = 3
    data[3] = 4
    data[4] = 5
    data[5] = 6
    data[6] = 7
    data[7] = 8

   $ ./can_send
   this is a can send demo
   can_id
   = 0x123
   can_dlc = 8
   data[0] = 1
   data[1] = 2
   data[2] = 3
   data[3] = 4
   data[4] = 5
   data[5] = 6
   data[6] = 7
   data[7] = 8
  $ ./can_send