Skip to content

Latest commit

 

History

History
190 lines (138 loc) · 6.02 KB

README.md

File metadata and controls

190 lines (138 loc) · 6.02 KB
Raw

Raspberry Pi CAN configuration

In this README you will find:

MCP2515 SPI-to-CAN module pinout

RPi Pin RPi Label CAN Module
17 3.3V VCC
20 GND GND
19 GPIO10 MOSI (SI)
21 GPIO9 MISO (SO)
22 GPIO25 INT
23 GPIO11 SCK
24 GPIO8 CS

Useful website for Raspberry Pi pinout

Automatic setup

Run setup.sh: every command is explained in this README.

Manual setup

Installing dependencies

sudo apt install can-utils

Configure SPI for MCP2515

Append the following lines in /boot/firmware/config.txt:

### SPI ###
dtparam=spi=on

### CAN-BUS overlay ###
dtoverlay=mcp2515-can0,oscillator=16000000,interrupt=25
dtoverlay=spi-bcm2835

Load CAN modules in OS during boot

Copy the file can.conf in /etc/modules-load.d/

Enable CAN interface

Append the following lines in /etc/network/interfaces

auto can0
iface can0 can static
	bitrate 500000

Testing

For testing the CAN connectivity, first of all you should check the output of ifconfig. If it shows a CAN interface running, you should be all good on the Raspberry side, if it doesn't, check the troubleshooting section.

Testing the Raspberry Pi alone

Note: this will test only the Raspberry-MCP2515 connection, without considering the TJA1050 and, therefore, the CAN Bus itself.

You will need two tty sessions, it is possible connecting your PC to the Raspberry both with UART and SSH at the same time.

On one session you have to run:

candump can0

And on the other you can send messages:

cansend can0 000#11223344

On the candump session, if everything is working correctly, you should see:

  can0  000   [4]  11 22 33 44

If it's not, check the troubleshooting section

Testing the Raspberry Pi with another CAN node

You can connect a CAN node on the bus, so that you can test also the CAN Bus itself. In order to do that, in this repo it is included a Platformio project in the esp-can-test folder. It periodically sends data and prints on the serial output the data that it receives.

Note: to avoid issues with VSCode and Platformio, you should open that folder with another window of VSCode, not accessing it having as project root this repository.

Troubleshooting

When you connect the hardware CAN Interface to the Raspberry Pi, you can use the command ifconfig to check whether the Raspberry has correctly initialized SocketCAN and connected to the MCP2515. If no CAN interface is showed in ifconfig, something went wrong.

Check if CAN modules are loaded in the OS

In order to check if the SocketCAN OS modules are loaded, run this command:

lsmod | grep "can"

If the modules are correctly loaded, you should see the following:

can_raw     ######  0
can         ######  1 can_raw
can_dev     ######  1 mcp251x

Check SPI connection between the RPi and the MCP2515

To check the SPI connection between the Raspberry and the MCP2515 run:

dmesg | grep "spi"

If it shows only the following message, the MCP2515 is connected correctly:

[   ##.######] mcp251x spi0.0 can0: MCP2515 successfully initialized.

In the case of an error message is shown, there probably is some physical connection failure. Anyway, it can show several error codes, in order to understand them, it can be convenient to Google them.

In the following example, error -110 means a timeout error.

[   ##.######] mcp251x spi0.0: MCP251x didn't enter in conf mode after reset
[   ##.######] mcp251x spi0.0: Probe failed, err=110
[   ##.######] mcp251x: probe of spi0.0 failed with error -110

In some cases, it can show the successfully initialized message, followed by an error. Usually, by empirical experience, it happens when the connection between the MCP2515 and the TJA1050 is not working, so in that case you should check the physical connection between the two integrated circuits or the powering of the TJA1050.

Note: if you modify something, you should reboot the system in order to restart SPI and see the results of your changes. To avoid that, you can "restart" the SPI OS module:

  1. Find the name of the SPI module

    spi_bcm2835 is the name of the SPI OS module on the newest Raspberry's, please check if you Raspberry has a different module, you can do that performing the following:

    lsmod | grep "spi"

    As a result, you will find the SPI module listed with lsmod.

  2. Remove and re-add the module (assuming that the name is spi_bcm2835, otherwise change it with the result of the previous point):

    rmmod spi_bcm2835
modprobe spi_bcm2835

Other useful resources

A collection of resources that have been used when working with CAN on the Raspberry Pi. Some mistakes have been noted in the links, so, please, be careful and use this README before checking them.