Able to transmit the data but not receiving the data (USART3)

[Santosh Ghorpade]

Posted on June 30, 2017 at 11:45

Hello,

I am working on the USART3 of NUCLEO-F413ZH. I am able to transmit the data but not receiving the data. Here is the Program

&sharpinclude 'stm32f4xx.h'

&sharpinclude 'misc.h'&sharpinclude 'stm32f4xx_usart.h'&sharpinclude 'stm32f4xx_gpio.h'&sharpinclude 'stm32f4xx_rcc.h'

uint16_t rec_data;

&sharpdefine MAX_STRLEN 12 // this is the maximum string length of our string in characters

volatile char received_string[MAX_STRLEN+1]; // this will hold the recieved stringvoid init_USART3();void USART_puts(USART_TypeDef* USARTx, volatile char *s);void GPIO_config();void EXTI_Config();void main(){ GPIO_config(); init_USART3(); EXTI_Config(); USART_puts(USART3, 'Hello'); while(1) {

}

}

void GPIO_config(){ GPIO_InitTypeDef GPIO_InitStruct;

RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD , ENABLE);

GPIO_InitStruct.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9; // Pins 8 (TX) and 9 (RX) are used

GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF; // the pins are configured as alternate function so the USART peripheral has access to them GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz; // this defines the IO speed and has nothing to do with the baudrate! GPIO_InitStruct.GPIO_OType = GPIO_OType_PP; // this defines the output type as push pull mode (as opposed to open drain) GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL; // this activates the pullup resistors on the IO pins GPIO_Init(GPIOD, &GPIO_InitStruct); // now all the values are passed to the GPIO_Init() function which sets the GPIO registers

GPIO_PinAFConfig(GPIOD, GPIO_PinSource0, GPIO_AF_USART3);

GPIO_PinAFConfig(GPIOD, GPIO_PinSource1, GPIO_AF_USART3);

}

void init_USART3()

{ USART_InitTypeDef USART_InitStruct; // this is for the USART3 initilization

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);

USART_InitStruct.USART_BaudRate = 115200; // the baudrate is set to the value we passed into this init function

USART_InitStruct.USART_WordLength = USART_WordLength_8b;// we want the data frame size to be 8 bits (standard) USART_InitStruct.USART_StopBits = USART_StopBits_1; // we want 1 stop bit (standard) USART_InitStruct.USART_Parity = USART_Parity_No; // we don't want a parity bit (standard) USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None; // we don't want flow control (standard) USART_InitStruct.USART_Mode = USART_Mode_Tx | USART_Mode_Rx; // we want to enable the transmitter and the receiver USART_Init(USART3, &USART_InitStruct); // again all the properties are passed to the USART_Init function which takes care of all the bit setting

USART_ITConfig(USART3, USART_IT_RXNE, ENABLE); // enable the USART3 receive interrupt

USART_Cmd(USART3, ENABLE);}

void USART_puts(USART_TypeDef* USARTx, volatile char *s)

{ while(*s) { // wait until data register is empty while( !(USARTx->SR & 0x00000040) ); USART_SendData(USARTx, *s); *s++; }}void EXTI_Config(){ NVIC_InitTypeDef NVIC_InitStructure; // this is used to configure the NVIC (nested vector interrupt controller)

NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn; // we want to configure the USART3 interrupts

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;// this sets the priority group of the USART3 interrupts NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; // this sets the subpriority inside the group NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; // the USART3 interrupts are globally enabled NVIC_Init(&NVIC_InitStructure); // the properties are passed to the NVIC_Init function which takes care of the low level stuff

USART_Cmd(USART3, ENABLE);

}void USART3_IRQHandler(void){ if( USART_GetITStatus(USART3, USART_IT_RXNE) ) { static uint8_t cnt = 0; char t = USART3->DR;

if( (t != '\n') && (cnt < MAX_STRLEN) ){

received_string[cnt] = t; cnt++; } else{ cnt = 0; USART_puts(USART3, received_string); } }}#usart #stm32f413