Posted on February 07, 2018 at 06:10I have been trying to get the USART to work on the stm32f3 discovery for a while without any success. Currently, the TX pin (PA2) is at a constant 3.3V, the RX pin (PA3) is at a constant 0V. I am using an FTDI Basic breakout board to read the USART, and I am using the keil uvision 5 IDE.
The code is given below:
/* Includes ------------------------------------------------------------------*/
&sharpinclude <stm32f30x.h>
&sharpinclude <stm32f30x_rcc.h>
&sharpinclude <stm32f30x_rcc.c>
&sharpinclude <stm32f30x_gpio.h>
&sharpinclude <stm32f30x_gpio.c>
&sharpinclude <stm32f30x_misc.h>
&sharpinclude <stm32f30x_misc.c>
&sharpinclude <stm32f30x_tim.h>
&sharpinclude <stm32f30x_tim.c>
&sharpinclude <stm32f30x_usart.h>
&sharpinclude <stm32f30x_usart.c>
//&sharpinclude <arm_math.h>
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
volatile int ms;
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/
void SysTick_Handler(void)
{
ms++;
}
/**
* @brief Main program.
* @param None
* @retval None
*/
int main(void)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;
NVIC_InitTypeDef NVIC_InitStruct;
/*GPIO configuration for indicator LED*/
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOE,ENABLE);
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_8|GPIO_Pin_9|GPIO_Pin_10|GPIO_Pin_11|GPIO_Pin_12;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOE,&GPIO_InitStruct);
//Turn LED on
GPIO_SetBits(GPIOE,GPIO_Pin_8|GPIO_Pin_12);
/*GPIO configuration for USART. PA2 = USART2_TX, PA3 = USART2_RX*/
//Enable clock for GPIOA
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA,ENABLE);
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_3;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA,&GPIO_InitStruct);
//AF configuration
GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_7);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_7);
/*USART configuration*/
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);
USART_Cmd(USART2, ENABLE);
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_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStruct);
//Enable RXNE interrupt
USART_ITConfig(USART2,USART_IT_RXNE,ENABLE);
GPIO_SetBits(GPIOE,GPIO_Pin_9);
//Enable USART global interrupt
//NVIC_EnableIRQ(USART2_IRQn);
NVIC_InitStruct.NVIC_IRQChannel = USART2_IRQn;
NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStruct);
GPIO_SetBits(GPIOE,GPIO_Pin_10);
if (SysTick_Config(SystemCoreClock / 1000))
{
/* Capture error */
while (1);
}
GPIO_SetBits(GPIOE,GPIO_Pin_11);
while (1)
{
if (ms>99){
USART_SendData(USART2,'S');
while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET){};
if (GPIO_ReadOutputDataBit(GPIOE,GPIO_Pin_12)){
GPIO_ResetBits(GPIOE,GPIO_Pin_12);
}
else{
GPIO_SetBits(GPIOE,GPIO_Pin_12);
}
ms=0;
}
}
}
void USART2_IRQHandler(void){
//RXNE handler
if(USART_GetITStatus(USART2,USART_IT_RXNE) != RESET){
//If recieved 't', toggle LED, transmit 'T'
if((char)USART_ReceiveData(USART2) == 't'){
//Toggle LED
if (GPIO_ReadOutputDataBit(GPIOE,GPIO_Pin_8)){
GPIO_ResetBits(GPIOE,GPIO_Pin_8);
}
else{
GPIO_SetBits(GPIOE,GPIO_Pin_8);
}
USART_ClearITPendingBit(USART2,USART_IT_RXNE);
//USART_SendData(USART1,'T');
//while(USART_GetFlagStatus(USART2,USART_FLAG_TXE)==RESET){}
}
}
}
#stm32f3-discovery #usart
