AnsweredAssumed Answered

Problem on routing of uart signals

Question asked by .michele. on Jan 13, 2014
Latest reply on Jan 14, 2014 by .michele.

Hi,

I have the stn32f4 discovery kit, and I tried to run the following code to send chracters to the uart :







-------------------------------------------------------

#include "stm32f4xx.h"
 
/**************************************************************************************/
 
void RCC_Configuration(void)
{
  /* Enable GPIO clock */
  RCC_AHB1PeriphClockCmd (RCC_AHB1Periph_GPIOA, ENABLE);
 
  /* Enable USART clock */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
}
 
/**************************************************************************************/
 
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
 
  /* Connect PA9 or PA1 to USART1_Tx */
//GPIO_PinAFConfig(GPIOA, GPIO_PinSource9,  GPIO_AF_USART1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource1,  GPIO_AF_USART1);
 
  /* Connect PA10 or PA2 to USART1_Rx */
//GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_USART1);
  GPIO_PinAFConfig(GPIOA, GPIO_PinSource2,  GPIO_AF_USART1);
 
  /* Configure USART Tx as alternate function push-pull */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; // GPIO_Pin_1 or GPIO_Pin_9
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
 
  /* Configure USART Rx as alternate function push-pull */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; // GPIO_Pin_2 or GPIO_Pin_10
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}
 
/**************************************************************************************/
 
void USART1_Configuration(void)
{
  USART_InitTypeDef USART_InitStructure;
 
  /* USART resources configuration (Clock, GPIO pins and USART registers) ----*/

  USART_InitStructure.USART_BaudRate = 1200;
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;
  USART_InitStructure.USART_StopBits = USART_StopBits_1;
  USART_InitStructure.USART_Parity = USART_Parity_No;
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
  USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
 
  /* USART configuration */
  USART_Init(USART1, &USART_InitStructure);
 
  /* Enable USART */
  USART_Cmd(USART1, ENABLE);
}
 
/**************************************************************************************/
 
int main(void)
{
  RCC_Configuration();
 
  GPIO_Configuration();
 
  USART1_Configuration();
 
  while(1)
  {
    while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET); // Wait for Empty
 
    USART_SendData(USART1, 0x49); // Send 'I'
  }
 
  while(1); // Don't want to exit
}
 
/**************************************************************************************/
 
#ifdef  USE_FULL_ASSERT
 
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t* file, uint32_t line)
{
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
 
  /* Infinite loop */
  while (1)
  {
  }
}
#endif


-------------------------------------------------------







This code runs well if I assign uart TX to pin PA9 and RX to PA10, but if I try to assign pins PA1 and PA2 for TX and RX, I cannot see the output signal (both signals stuck to Vcc).

Can you help me?

Thank you in advance

regards,

Michele

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