143 lines
4.0 KiB
Markdown
143 lines
4.0 KiB
Markdown
This document describes how the STM32F0 port operates and how to work with
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tiny CAN-enabled boards.
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Required components
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===================
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#### MCP2515 module
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or this
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#### St-link dongle
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Adding CAN bus to Raspberry Pi
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==============================
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(Based on Quick Guide https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=141052)
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First of all, (only if you have small CAN module) it’s necessary to modify the CAN-module from ebay, because it has
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only one VCC pin, but the MCP2515 needs to be powered from 3V3 and the TJA1050
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CAN-transceiver needs to be powered from 5V. Powering both chips from 5V would
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work, but then a level-shifter for the SPI would be needed. The Pi's GPIO pins
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are NOT 5V tolerant. Cut a trace on the PCB and soldered a pin onto the trace
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to deliver 5V only to the TJA1050. Be sure to cut the trace before the capacitor:
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Next connect the module:
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| MCP2515 | Raspberry Pi |
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| --- | --- |
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| VCC | 1 (3V3) |
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| TJA 1050 VCC | 2 (5V) |
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| GND | 6 (GND) |
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| CS | 24 (CE0) |
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| MISO | 21 (MISO) |
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| MOSI | 19 (MOSI) |
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| SCK | 23 (SCK) |
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| INT | 22 (GPIO25) |
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Install can-utils:
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> sudo apt-get install can-utils
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To activate the driver for the MCP2515 you have to add a kernel overlay, to do
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so edit the /boot/config.txt
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> sudo nano /boot/config.txt
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And add the following lines (set oscillator value according to crystal on your board):
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```
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dtparam=spi=on
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dtoverlay=mcp2515-can0,oscillator=8000000,interrupt=25
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dtoverlay=spi1-1cs
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```
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Now reboot, after the reboot try to setup the the can interface:
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> sudo ip link set can0 up type can bitrate 500000
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If no errors occurred, the can interface should be ready now.
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To make the CAN-interface permanent, add the following lines to /etc/network/interfaces
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```
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auto can0
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iface can0 can static
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bitrate 500000
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```
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Communicating over CAN
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======================
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Use "Serial over CAN" emulator software to establish connection:
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https://github.com/Delsian/CanSerial
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Install st-link on Raspberry Pi
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===============================
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> sudo apt-get update
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> sudo apt-get install cmake
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> sudo apt-get install libusb-1.0-0-dev
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> git clone https://github.com/texane/stlink stlink-repo
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> cd stlink-repo
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> make
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> cd build/Release/
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> sudo make install
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Copy to /etc/udev/rules.d/49-stlinkv2.rules:
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```
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# stm32 discovery boards, with onboard st/linkv2
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# ie, STM32L, STM32F4.
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# STM32VL has st/linkv1, which is quite different
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="3748", \
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MODE:="0666", \
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SYMLINK+="stlinkv2_%n"
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", \
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KERNEL!="sd*", KERNEL!="sg*", KERNEL!="tty*", SUBSYSTEM!="bsg", \
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MODE:="0666", \
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SYMLINK+="stlinkv2_%n"
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", \
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KERNEL=="sd*", MODE:="0666", \
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SYMLINK+="stlinkv2_disk"
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", \
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KERNEL=="sg*", MODE:="0666", \
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SYMLINK+="stlinkv2_raw_scsi"
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", \
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SUBSYSTEM=="bsg", MODE:="0666", \
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SYMLINK+="stlinkv2_block_scsi"
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SUBSYSTEMS=="usb", ATTRS{idVendor}=="0483", ATTRS{idProduct}=="374b", \
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KERNEL=="tty*", MODE:="0666", \
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SYMLINK+="stlinkv2_console"
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# If you share your linux system with other users, or just don't like the
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# idea of write permission for everybody, you can replace MODE:="0666" with
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# OWNER:="yourusername" to create the device owned by you, or with
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# GROUP:="somegroupname" and control access using standard unix groups.
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```
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Now "make flash" command can upload HEX into connected board
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Pins allocation
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===============
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Configurations with CAN and Serial port uses different pins, and during enumeration
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process firmware reports all possible pin names. But actually you can use only
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existing pins, not involved in communication. Wrong pins will generate shutdown.
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