Support for STM32G0B1 with different CAN pin numbers, CAN2 on PB0/PB1

[rondlh]

I'm trying to get CAN to work on a BTT EBB CAN board (https://github.com/bigtreetech/EBB) which is a 3D printer tool head board. The version V1.2 board I have uses a STM32G0B1 MCU, which uses pin number for the CAN bus that are currently not supported by the library:

STM32G0 CAN bus pin numbers: (All are AF3) CAN1_RX PA11 CAN1_TX PA12 CAN2_RX PB0 (Used by BTT EBB42 V1.2) CAN2_TX_PB1 (Used by BTT EBB42 V1.2) CAN2_RX PB5 CAN2_TX_PB6 CAN1_RX PA8 CAN1_TX PA9 CAN2_RX PB12 CAN2_TX_PB13 CAN2_RX PC2 CAN2_TX_PC3 CAN1_RX PC4 CAN1_TX_PC5

I could give this a try myself, some pointers in the right direction would be appreciated.

[rondlh]

Would this do the trick? (Added in the CAN2 pin section).

    if (_pins == ALT_2) // CAN2 MAPPED TO PIN B0/B1 FOR STM32G0
    {
      __HAL_RCC_GPIOB_CLK_ENABLE();
      #if defined(__HAL_RCC_AFIO_CLK_ENABLE)
        __HAL_AFIO_REMAP_CAN2_ENABLE(); // To use PB0/1 pins for CAN2. Don't ask me why this has different name than for CAN1.
        __HAL_RCC_AFIO_CLK_ENABLE();
        GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
        GPIO_InitStruct.Pin = GPIO_PIN_0;          // CAN_RX, PB0
        GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
        HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
        GPIO_InitStruct.Pin = GPIO_PIN_1;          // CAN_TX, PB1
      #else
        GPIO_InitStruct.Alternate = GPIO_AF3_CAN2; // AF3
        GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1;
        GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
      #endif
      GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
      HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
    }

[pazi88]

STM32G0B1 uses CAN-FD, which is not yet supported with this library. My goal is to get it working some day, but no ETA.