printf problem in atollic truestudio stm32f103

Posted on December 15, 2015 at 15:32

Hello Jeff

>> I saw some thread that need to attach sys_call.c and tiny_printf.c? Is that true?

you need to add only syscalls.c that includes the_write and _read functions tiny_printf.c is a minimal implementation of printf features (like newlib-nano) : used to optimize the code size in your case you need the _write function

int

_write(

int

file,

char

*ptr,

int

len)
{
int

DataIdx;
for

(DataIdx = 0; DataIdx < len; DataIdx++)
{
__io_putchar( *ptr++ );
}
return

len;
}

then override the __io_putchar to write *ptr to USART or put the implementation within _write itself.

>> however it doesnot work.

In that case, please ensure that your USART is correctly initialized. For guidance, you can inspire from STM32CubeF1 V1.2.0\Projects\STM32VL-Discovery\Examples\UART\UART_Printf or fromSTM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\USART\Printf Using Standard Peripherals Library:

/**
* @brief Retargets the C library printf function to the USART.
* @param None
* @retval None
*/
int
__io_putchar(
int
ch)
{
/* Place your implementation of fputc here */
/* e.g. write a character to the USART */
USART_SendData(EVAL_COM1, (uint8_t) ch);
/* Loop until the end of transmission */
while
(USART_GetFlagStatus(EVAL_COM1, USART_FLAG_TC) == RESET)
{}
return
ch;
}

Where EVAL_COM1 could be USART1 (it depends on your implementation). Regards, TarekB

Posted on December 29, 2015 at 03:41

thanks it solved