Quelltext der Seite WSAL14882 – RS485 CAN HAT/en

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'''Documentation notice:''' This technical documentation was independently rewritten from an archived supplier source. Check technical details and commands against the product version and manufacturer documentation before use.

== Summary ==
The RS485 CAN HAT adds CAN and RS485 communication to a Raspberry Pi via the 40-pin GPIO header. It uses an MCP2515 CAN controller over SPI and an SP3485 transceiver for half-duplex RS485 operation.

== Related products at JW Tech ==
* [https://shop.jw-tech.eu/p/WSAL14882 WSAL14882 – RS485 CAN HAT for Raspberry Pi]

== Technical overview ==
* Standard 40-pin Raspberry Pi GPIO header compatible with all Raspberry Pi models, including Raspberry Pi 4B.
* CAN function: onboard MCP2515 CAN controller via SPI interface with SN65HVD230 transceiver (Texas Instruments).
* RS485 function: controlled via UART, half-duplex operation; the SP3485 transceiver supports automatic TX/RX control without additional programming.
* Onboard TVS suppresses surge voltages and electrostatic discharge on the RS485 bus.
* Dimensions: 65 mm x 30 mm; mounting hole diameter 3.0 mm; operating voltage 3.3 V.
* CAN bus pins: SCK, MOSI, MISO, CS (CE0), and interrupt output at pin 25 (BCM).
* RS485 bus pins: RXD, TXD via UART; RSE control signal at BCM pin 4.
* Factory default uses hardware auto mode for RS485 transmit/receive; manual software control can be enabled by soldering a 0-ohm resistor.
* For CAN operation, add 'dtparam=spi=on' and the dtoverlay 'mcp2515-can0' to /boot/config.txt (or /boot/firmware/config.txt for Bookworm/Ubuntu).
* After reboot, verify initialization with 'dmesg &#124; grep -i "\(can\&#124;spi\)'.

'''Commands and examples – verify before use:''' 
<syntaxhighlight lang="text">
sudo nano /boot/config.txt
dtparam=spi=on
dtoverlay=mcp2515-can0,oscillator=12000000,interrupt=25,spimaxfrequency=2000000
sudo reboot
dmesg | grep -i '\(can\|spi\)','sudo ip link set can0 up type can bitrate 1000000
sudo ifconfig can0 txqueuelen 65536
sudo ifconfig can0 up
ifconfig
sudo apt-get install can-utils
sudo ip link set can0 down
sudo ip link set can0 type can bitrate 1000000 loopback on
candump can0
cansend can0 000#11.22.33.44
</syntaxhighlight>

== Notes and version constraints ==
* On Bookworm systems only the lgpio library is available; bcm2835 and wiringPi cannot be installed or used.
* The oscillator setting depends on purchase date: pre-August 2019 boards use an 8 MHz oscillator; newer boards use 12 MHz.
* For very high baud rates, it is recommended to use the manual RS485 transceiver because transistor switching speed limits the automatic mode.
* When testing with a single module: enable loopback mode and verify with 'candump'/'cansend'.
* Ensure both ends of the CAN bus have 120-ohm terminating resistors and that the bit rate is identical on both sides.
* If initialization fails: check the physical connection, confirm SPI and the MCP2515 kernel driver are enabled, and that a reboot was performed after configuration changes.

== Source and revision record ==
* [https://www.waveshare.com/wiki/RS485_CAN_HAT RS485 CAN HAT - Waveshare Wiki]
* Source revision: 110789
* Captured: 2026-08-31T02:31:38+00:00
* SHA-256: <code>4a716167cb065406906af14e64473e3b0368b69f1e23823f75e1979a0bac156e</code>