usart communication : from usart3 to usart1

[louati-amir]

Posted on January 14, 2014 at 10:57

I wrote this code in order to test usart communication in fact When I press the user button an interruption in generated witch send data from usart3 to the usart1 when data is recived an interruption is generated witch togel the 4 leds in the board.

I connected the pin PB7 to the PB10 in the hardware. but it didn't work :\ I cheked by debugging the interruption is generated when i press the button so the problem look from the usart configuration.

#include ''stm32f4xx.h''
#include ''stm32f4xx_gpio.h''
#include ''stm32f4xx_rcc.h''
#include ''stm32f4xx_tim.h''
#include ''stm32f4xx_usart.h''
#include ''misc.h''
#include ''stm32f4xx_exti.h''
#include ''stm32f4xx_syscfg.h''
/*******************************************************************/
static void EXTILine0_Config(void)
{
EXTI_InitTypeDef EXTI_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
/* Enable GPIOA Clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
/* Enable SYSCFG clock */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
/* Configure PA0 pin as input floating */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect EXTI Line0 to PA0 pin */
SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
/* Configure EXTI Line0 */
EXTI_InitStructure.EXTI_Line = EXTI_Line0;
EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; 
EXTI_InitStructure.EXTI_LineCmd = ENABLE;
EXTI_Init(&EXTI_InitStructure);
/* Enable and set EXTI Line0 Interrupt to the lowest priority */
NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
/**************************************************************************************/
void LED_Configuration(void)
{ 
/* GPIOD clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_Init(GPIOD, &GPIO_InitStructure);
}
/**************************************************************************************/
void USART_configuration(void){
// USART1 {RX : B7 ; TX : B6}
// USART3 {RX : B11 ; TX : B10}
/* 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
*/ 
/* GPIOB clock enable */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
/* USART 1 & 3 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
//config USART 1 & 3 config pin
/*-------------------------- GPIO Configuration ----------------------------*/
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11 |GPIO_Pin_6 | GPIO_Pin_7;
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);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_USART1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_USART1);
//config internal register for usar3 & usart1
USART_InitTypeDef USART_InitStructure;
USART_InitStructure.USART_BaudRate = 9600;
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(USART1, &USART_InitStructure);
USART_Cmd (USART1, ENABLE);
USART_Init(USART3, &USART_InitStructure);
USART_Cmd (USART3, ENABLE);
//enable receive data interruption 
USART_ITConfig(USART1,USART_IT_RXNE,ENABLE);
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0E;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
/***************************************************************************************/
void EXTI0_IRQHandler(void){
EXTI_ClearITPendingBit(EXTI_Line0);
USART_SendData(USART3,0X0F); 
for(int i = 0; i<0XFFFFF; i++);
}
/**************************************************************************************/
void USART1_IRQHandler(void){
uint16_t data = USART_ReceiveData(USART1);
if (data == 0X0F){
GPIO_ToggleBits(GPIOD, GPIO_Pin_12 | GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15);
}
}
/**************************************************************************************/
int main(void)
{ 
LED_Configuration();
EXTILine0_Config();
USART_configuration();
while(1)
{
}
}
/**************************************************************************************/

[Tesla DeLorean]

Posted on January 14, 2014 at 13:21

/* Enable GPIOA Clock */
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE); ??? D ???
 You might want to check for TXE before sending data
 Can you see the signal on the pin with a scope?

[louati-amir]

Posted on January 14, 2014 at 14:24

it a mistake for D it's A but it work fine i checked the interrupt it's working when I press the button.

I checked the TX Buffer of the USART3: it's not empty. but why it's not sending the data written in the buffer? what it's waiting for ? I do not have socope.

[jpablo]

Posted on January 14, 2014 at 19:12

You can try something like this (I made something similar and is working for me):

receiving part:

void USART1_IRQHandler(void)
{
if( USART_GetITStatus(USART1, USART_IT_RXNE) ) //if I receive something
{
// then, turn on leds
}
}
}

For the sending part:

int a = 100; //what you want
while(USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET);
USART_SendData(USART3,a);

You can use a terminal program for testing purpose, I'm using HTerm. Hope is helpful. Pablo