AnsweredAssumed Answered

STM32F4 USART receiving sting

Question asked by rabah.mohamed on Sep 29, 2016
Latest reply on Oct 2, 2016 by rabah.mohamed
I started 2 days ago working on STM32f4 discovery board, and i have basic background in C programming.
I succedded in sending and receiving characters using USART with interrupt, but whenever i try to receive a string nothing happenes.
here is my code
#include "stm32f4xx.h"
#include "stm32f4xx_usart.h"
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_gpio.h"
#include "misc.h"
 
 
void Delay(__IO uint32_t nCount)
{
  while(nCount--)
  {
  }
}
void setup_Pheriph()
{
    GPIO_InitTypeDef GPIO_InitStruct;
    USART_InitTypeDef USART_InitStruct;
    NVIC_InitTypeDef NVIC_InitStruct;
 
    //ENABLE PERIPH CLOCK FOR USART2
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
    //ENABLE GPIOA CLOCK
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    //ENABLE GPIOD CLOCK
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
 
    //SETUP GPIOA PINS FOR Tx AND Rx
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;   //SINCE WE HAVE USED ALTERNATIVE FUNCTION WE SHOULD ASIGN IT DOWN
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_25MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;   //PULL UP RESISTORS
    GPIO_Init(GPIOA, &GPIO_InitStruct);
 
    //SETUP GPIOD PINS FOR BLINKING LED
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_13 |GPIO_Pin_12;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_25MHz;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_Init(GPIOD, &GPIO_InitStruct);
 
    //SETTING UP AF FOR UARTS2
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);   //WE SET PIN2 AND 3 AS AF FOR UART2
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);
 
    //SETUP USART CONFIG
    USART_InitStruct.USART_BaudRate = 9600;
    USART_InitStruct.USART_WordLength = USART_WordLength_8b;
    USART_InitStruct.USART_StopBits = USART_StopBits_1;
    USART_InitStruct.USART_Parity = USART_Parity_No;
    USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStruct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;    //WE SETUP USART FOR Rx AND Tx
    USART_Init(USART2, &USART_InitStruct);
 
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);  //SETUP INTERRUPT REQUEST FOR USART FOR ONLY RECEIVE
 
    //SETTING UP INTERRUPT REQUEST NVIC
    NVIC_InitStruct.NVIC_IRQChannel = USART2_IRQn;  //CHANNEL IS THE INTERRUPT NAME I WANT TO CONFIGURE
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;    //ENABLE USART GLOBALLY
    NVIC_Init(&NVIC_InitStruct);
 
    //ENABLE USART2 PERIPHERAL
    USART_Cmd(USART2, ENABLE);
}
 
void USART_send_char(USART_TypeDef *USARTx, char c)
{
    while(!USART_GetITStatus(USARTx,USART_FLAG_TXE));
 
    USART_SendData(USARTx, c);
}
 
void USART_send_string(USART_TypeDef *USARTx, volatile char *str)   //WE PASS ANY USART AND STRING
{
    while(*str)
    {
 
        /*while(!(USARTx->SR & 0x00000040));    //P.993 SR-> STATUS REGISTER, 0X040 -> TC FLAG
                                        //LOOP TILL TC FLAG = 1, WHICH MEANS DATA IS TRANSFERED
 
        //ANOTHER WAY IS LIKE THIS*/
        while(!USART_GetFlagStatus(USARTx, USART_FLAG_TC ));    //STAY HERE WHILE THIS FLAG IS ZERO
        USART_SendData(USARTx, *str);
        *str++;
    }
}
 
uint16_t USART_receive_char(USART_TypeDef *USARTx)
{
    //WAIT UNTIL CHAR IS RECEIVED
    while(!USART_GetFlagStatus(USARTx, USART_FLAG_RXNE));
    //READ RECEIVED CHAR
    return USART_ReceiveData(USARTx);
}
 
uint16_t* USART_receive_string(USART_TypeDef *USARTx)
{
    uint16_t string[20],x;
    static int cnt = 0;
    x=USART_receive_char(USARTx);
 
    while(x!='\n' || x!='\r')
    {
        //STORE THE RECEIVED CHAR INTO ARRARY
        string[cnt++]=x;
    }
    string[cnt]='\0';
    return string;
}
 
int main(void)
{
 
    setup_Pheriph();
 
 
    USART_send_string(USART2, "Welcome Rabah!\r\n");
 
 
    while(1)
    {
 
 
    }
}
 
uint16_t rec_char;
uint16_t *rec_string;
 
void USART2_IRQHandler()
{
 
 
    /*rec_char = USART_receive_char(USART2);
    if(rec_char == 'o')
        GPIO_WriteBit(GPIOD, GPIO_Pin_13, Bit_SET);
    if(rec_char == 'f')
        GPIO_WriteBit(GPIOD, GPIO_Pin_13, Bit_RESET);*/
 
    if(rec_string == "red")
    {
        GPIO_WriteBit(GPIOD, GPIO_Pin_13, Bit_SET);
    }
    else
    {
        USART_send_string(USART2,rec_string);
    }
     
}

Outcomes