Posted by ronk on 2017-10-23 19:33

I ran into the same problem using the HAL_UART_Receive_() function (No DMA).

I implemented your workaround by setting ‘len’ to 1 inside the _read() function in the syscalls.c module. This works. But without the DMA, the function does not block as it should.

I fixed this by waiting for success in my __io_getchar() function.

int __io_getchar(void) {
HAL_StatusTypeDef Status = HAL_BUSY;
uint8_t Data;

while(Status != HAL_OK)
Status = HAL_UART_Receive(&huart6, &Data, 1, 10);

return(Data);
}

I also removed the increment of ‘ptr’ in the _read() function since I don’t know if ‘ptr’ is reinitialized each time _read() is called.

I don’t feel good about modifying the syscalls.c module that I didn’t write but downloaded. It won’t have my changes the next time I download it.

Posted by MarkV6 on 2017-10-24 13:44

Just repied to topic with the same question:

bool getchar(uint8_t * ch)
{
       // check for overflow and clear
	if (__HAL_UART_GET_FLAG(&huart1, UART_FLAG_ORE))
		__HAL_UART_CLEAR_FLAG(&huart1, UART_FLAG_ORE);

	if (__HAL_UART_GET_FLAG(&huart1, UART_FLAG_RXNE))
	{
		*ch = huart1.Instance->RDR & 0x1FF;
		return true;
	}

	return false;
}

void _write(int file, char *ptr, int len)
{
		HAL_UART_Transmit(&huart1, (uint8_t*) ptr, len, 10);
}

The printf will call the _write function. You need to end it with \r\n or nothing will be printed.
I would like to know how to redirect the putc because this is not possible:

if (sci1_get(&ch))
				printf("%c", ch);