{"id":3579,"date":"2023-04-17T14:23:36","date_gmt":"2023-04-17T13:23:36","guid":{"rendered":"https:\/\/pmortensen.eu\/world2\/?p=3579"},"modified":"2025-09-18T20:03:31","modified_gmt":"2025-09-18T19:03:31","slug":"gotcha-using-can-2-on-arm-microcontrollers-stm32f415-1bitsy","status":"publish","type":"post","link":"https:\/\/pmortensen.eu\/world2\/2023\/04\/17\/gotcha-using-can-2-on-arm-microcontrollers-stm32f415-1bitsy\/","title":{"rendered":"Gotcha using CAN 2 on ARM microcontrollers (e.g., STM32F415 on 1Bitsy)"},"content":{"rendered":"

The short version: The CAN bus<\/a> 2 channel on ARM<\/a> microcontrollers<\/a> only works if CAN 1 is also set up<\/em><\/strong>… That is, CAN 2 can not be set up independently; for it to work at all, the other CAN channel, CAN 1, must also be set up. This isn’t mentioned anywhere in the documentation, not even the slightest hint (not even when retrospectively searching for it).<\/p>\n

This is demonstrated here for the 1Bitsy<\/a> board (based on the STM32F415<\/a> microcontroller; STM32F415RGT6) and using Forth<\/a> for exploration (Mecrisp Stellaris<\/a>), but it is believed this problem applies to all ARM microcontrollers with more than one CAN channel. <\/p>\n

<\/p>\n

Appendix B: Development board 1Bitsy<\/h2>\n

Schematics<\/a> (in PDF format). Direct Git link<\/a>.<\/p>\n

Pinouts<\/a> (GitHub view<\/a>)<\/p>\n

Appendix C: Microcontroller STM32F415<\/h2>\n

The one on the 1Bitsy is:<\/p>\n