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Does USART need max232 to PC

Question asked by hoang.van on Dec 2, 2012
Latest reply on Dec 3, 2012 by hoang.van
I used example code in here to send and echo char through UART. I connected PB10, PB11 right to RX and TX pin to FT232RL and connect it to USB's PC. On PC I'm using Hyperterminal with the correct baudrate, parity, stopbit. But I ca't send or recieve anything.
I changed the code to send any other character like 'a' or 'h' or 'o' to PC but all I receive is '|'
I think the fault is I'm using FT232RL (I test this IC work fine), Do I have to connect PB10, PB11 just to a USB-Serial and no need a MAX232 ???
Sorry I'm new-bie

This is code I coppied

// STM32 USART3 (Tx PB.10, Rx PB.11) STM32F4 Discovery - sourcer32@gmail.com
 
/**************************************************************************************/
 #include "stm32f4xx_usart.h"
 #include "stm32f4xx_gpio.h"
 #include "stm32f4xx_rcc.h"
void RCC_Configuration(void)
{
  /* --------------------------- System Clocks Configuration -----------------*/
  /* USART3 clock enable */
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
 
  /* GPIOB clock enable */
  RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
}
 
/**************************************************************************************/
 
void GPIO_Configuration(void)
{
  GPIO_InitTypeDef GPIO_InitStructure;
 
  /*-------------------------- GPIO Configuration ----------------------------*/
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
  GPIO_Init(GPIOB, &GPIO_InitStructure);
 
  /* Connect USART pins to AF */
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource10, GPIO_AF_USART3);
  GPIO_PinAFConfig(GPIOB, GPIO_PinSource11, GPIO_AF_USART3);
}
 
/**************************************************************************************/
 
void USART3_Configuration(void)
{
    USART_InitTypeDef USART_InitStructure;
 
  /* USARTx configuration ------------------------------------------------------*/
  /* USARTx configured as follow:
        - BaudRate = 9600 baud
        - Word Length = 8 Bits
        - Two Stop Bit
        - Odd parity
        - Hardware flow control disabled (RTS and CTS signals)
        - Receive and transmit enabled
  */
  USART_InitStructure.USART_BaudRate = 19200;
  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_Init(USART3, &USART_InitStructure);
 
  USART_Cmd(USART3, ENABLE);
}
 
/**************************************************************************************/
 void Delay(__IO uint32_t nCount)
{
  while(nCount--)
  {
  }
}
int main(void)
{
    RCC_Configuration();
 
    GPIO_Configuration();
 
  USART3_Configuration();
 
     while(1)
{
  if (USART_GetFlagStatus(USART3, USART_FLAG_RXNE) != RESET) // Character Ready
  {
    uint16_t ch;
 
    ch = USART_ReceiveData(USART3); // Grab it
 
    while(USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET); // Wait for Empty
   
    USART_SendData(USART3, ch);  // Echo it
  }
 
#define USART_FLAG_ERRORS (USART_FLAG_ORE | USART_FLAG_NE | USART_FLAG_FE | USART_FLAG_PE)
 
  if (USART_GetFlagStatus(USART3, USART_FLAG_ERRORS) != RESET) // Errors?
    USART_ReceiveData(USART3); // Clear Them
}
 
 }


The code I edited that I recieved only '|' on hyperterminal
     
while(1){
          USART_SendData(USART2, 'h'); // defined in stm32f4xx_usart.h
          Delay(0x3FFFFF);
     }

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