Posted by fedex03 on 2016-07-14 14:47

HI there,

I’m looking for the redirection of printf to UART2.

My MCU is a STM32F103VDT and I use UART2 to print debug on serial console.

On Keil I used this code to redirect the printf trough UART2:

int fputc(int ch, FILE *f)
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */

if ((char)ch == ‘\n’) /* Add a LF before \n — LF -> CR LF */
{
HAL_UART_Transmit(&huart2,(uint8_t*)”\r”,1,1);
}

HAL_UART_Transmit(&huart2,(uint8_t*)&ch,1,1); // 1 tick waiting (1ms) enough for 87us/byte at 115200

return ch;
}

But now this code not works when I compile with System WorkBench AC6.

Exploring the forum I found a hint regarding the redirection of UART.

It’s suggest to use this code to redirect the printf (I add my code into the function):

void __io_putchar(uint8_t ch)
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */

if ((char)ch == ‘\n’) /* Add a LF before \n — LF -> CR LF */
{
HAL_UART_Transmit(&huart2,(uint8_t*)”\r”,1,1);
}

HAL_UART_Transmit(&huart2,(uint8_t*)&ch,1,1); // 1 tick waiting (1ms) enough for 87us/byte at 115200

//return ch;
}

But this code not works.

Any suggestion?

Thanks