renardspark/SLGreen — reverse-engineered prompt

Build me an Arduino project that turns an Arduino or ESP32 with an MCP2515 CAN module into a cheap USB serial CAN adapter.

I want to flash one sketch, plug it into my computer, and use it from Linux with slcand, can0, candump, or SavvyCAN. It should speak the SLCAN / Lawicel style serial protocol, let the computer set the CAN speed, open and close the CAN bus, support listen only mode, send and receive normal CAN frames, support standard and extended frames, and answer basic version and serial number commands.

Please keep the hardware setup simple, SPI to the MCP2515, chip select on pin 10 by default, no INT pin required. Put the main settings near the top so I can change the MCP2515 clock, serial baud rate, chip select pin, and default CAN speed. Use the common Arduino MCP2515 library and include clear comments plus basic Linux usage notes. Look up current docs online if you need to.