Question
STM32G4 BSP's virtual com port fails to print character when UART register callback is turned on.
In a nutshell, as you turned on the UART register callback option as shown in the figure below, the virtual com port fails to print any items.
After further inspection, I believe it is a bug in `stm32g4xx_nucleo.c`, under function `BSP_COM_Init`. It seems like someone forget to index the `IsComMspCbValid` to find the validity of the given `COM`, as shown in code below.
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
static uint32_t IsComMspCbValid[COMn] = {0};
#endif
/**
* @brief Configures COM port.
* @PAram COM COM port to be configured.
* This parameter can be COM1
* @PAram COM_Init Pointer to a UART_HandleTypeDef structure that contains the
* configuration information for the specified USART peripheral.
* @retval BSP error code
*/
int32_t BSP_COM_Init(COM_TypeDef COM, COM_InitTypeDef *COM_Init)
{
int32_t ret = BSP_ERROR_NONE;
if(COM > COMn)
{
ret = BSP_ERROR_WRONG_PARAM;
}
else
{
#if (USE_HAL_UART_REGISTER_CALLBACKS == 0)
/* Init the UART Msp */
COM1_MspInit(&hcom_uart[COM]);
#else
if(IsComMspCbValid == 0U) // HERE
{
if(BSP_COM_RegisterDefaultMspCallbacks(COM) != BSP_ERROR_NONE)
{
return BSP_ERROR_MSP_FAILURE;
}
}
#endif
if(MX_LPUART1_Init(&hcom_uart[COM], COM_Init) != HAL_OK)
{
return BSP_ERROR_PERIPH_FAILURE;
}
}
return ret;
}This causes, `BSP_COM_RegisterDefaultMspCallbacks(COM)` never get called and the `COM` is never initialised. Thus the lack of response when using the `printf` function.
After adding indexing as shown in code below, the `printf` successfully work as intended.
if (IsComMspCbValid[COM] == 0U)
{
if (BSP_COM_RegisterDefaultMspCallbacks(COM) != BSP_ERROR_NONE)
{
return BSP_ERROR_MSP_FAILURE;
}
}
Hopefully, the team could fix this small issue.