USART Configuration

[definitely]

Posted on May 06, 2014 at 02:22

Hello everyone I need to use USART2 from my STM32F3 but I can't make it work. Here is my code. If someone can find my error please help me. 

&sharpinclude ''stm32f30x.h'' /**************************************************************************************/ void RCC_Configuration(void){  /* Enable GPIO clock */  RCC->AHBENR |= RCC_AHBENR_GPIODEN;   /* Enable USART clock */  RCC->APB1ENR |= RCC_APB1ENR_USART2EN;} /**************************************************************************************/ void GPIO_Configuration(void){   /* Connect PD5 to USART1_Tx */  GPIOD->MODER |= 2 << ( 5*2 ); // [ 9:8 ] MODER4[ 1:0 ] = 10b Alternate function on  // PIN C4 //GPIOC->OTYPER |= 1 << ( 5*1 ); // [ 4 ] OT4 = 1 Output as open drain GPIOD->OSPEEDR |= 3 << ( 5*2 ); // [ 9:8 ] OSPEEDR4[ 1:0 ] = 11b 50 MHz High-speed on PIN C4 //GPIOC->PUPDR &= ~( 3 << ( 5*2 ) ); // [ 9:8 ] PUPDR4[ 1:0 ] = 0 No pull-up/down om PIN C4 GPIOD->AFR[ 0 ] |= 7 << ( 5*4 );   /* Connect PD6 to USART1_Rx */ GPIOD->MODER |= 2 << (6*2);  // GPIO_Mode_AF GPIOD->AFR[0] |= 7 << (6*4);  //  AF7 } /**************************************************************************************/ void USART2_Configuration(void){   /* USART resources configuration (Clock, GPIO pins and USART registers) ----*/  /* USART configured as follow:        - BaudRate = 9600 baud        - Word Length = 8 Bits        - One Stop Bit        - No parity        - Hardware flow control disabled (RTS and CTS signals)        - Receive and transmit enabled  */  USART2->BRR = 72000000/9600; USART2->CR1 &= ~USART_CR1_OVER8; // Oversampling mode = 16  USART2->CR1 &= ~USART_CR1_M;  // Word length = 8 bits USART2->CR1 &= ~USART_CR1_PCE;  // No parity USART2->CR1 |= USART_CR1_TE;  // Transmitter enable USART2->CR1 |= USART_CR1_RE;  // Receiver enable USART2->CR1 |= USART_CR1_UE;  // USART enable USART2->CR2 &= ~(USART_CR2_STOP_1 | USART_CR2_STOP_0);} /**************************************************************************************/ void OutString(char *s){  while(*s)  {    while(!(USART2->ISR & USART_ISR_TXE)); // Wait for Empty     USART2->TDR =(USART2, *s++);  }} /**************************************************************************************/ int main(void){  RCC_Configuration();   GPIO_Configuration();   USART2_Configuration();   OutString(''This is an echo back test for USART1\r\n'');   while(1) // Don't want to exit  {    uint16_t ch;     while(!(USART2->ISR & USART_ISR_RXNE)); // Wait for Char     ch  = USART2->RDR; // Collect Char     while(!(USART2->ISR & USART_ISR_TXE)); // Wait for Empty     USART2->TDR=(USART2, ch); // Echo Char  }} /**************************************************************************************/ &sharpifdef  USE_FULL_ASSERT/**  * @brief  Reports the name of the source file and the source line number  *         where the assert_param error has occurred.  * @param  file: pointer to the source file name  * @param  line: assert_param error line source number  * @retval None  */void assert_failed(uint8_t* file, uint32_t line){  /* User can add his own implementation to report the file name and line number,     ex: printf(''Wrong parameters value: file %s on line %d\r\n'', file, line) */   /* Infinite loop */  while (1)  {  }}&sharpendif #usart-stm32f3

[Tesla DeLorean]

Posted on May 06, 2014 at 02:34

This is valid C?

USART2->TDR=(USART2, ch); // Echo Char USART2->TDR =(USART2, *s++); Sorry, really not interested in wading through register level code.

[definitely]

Posted on May 06, 2014 at 02:41

Yes it is valid. The problem is that I have a code that works with PC4 and PC5 (USART1) but I need to change it to USART2 which uses PD5 and PD6. I use this code for PC4 and PC5 and this totally works. 

#include ''stm32f30x.h'' /**************************************************************************************/ void RCC_Configuration(void){  /* Enable GPIO clock */  RCC->AHBENR |= RCC_AHBENR_GPIOCEN;   /* Enable USART clock */  RCC->APB2ENR |= RCC_APB2ENR_USART1EN;} /**************************************************************************************/ void GPIO_Configuration(void){   /* Connect PC4 to USART1_Tx */  GPIOC->MODER |= 2 << ( 4*2 ); // [ 9:8 ] MODER4[ 1:0 ] = 10b Alternate function on  // PIN C4 //GPIOC->OTYPER |= 1 << ( 4*1 ); // [ 4 ] OT4 = 1 Output as open drain GPIOC->OSPEEDR |= 3 << ( 4*2 ); // [ 9:8 ] OSPEEDR4[ 1:0 ] = 11b 50 MHz High-speed on PIN C4 //GPIOC->PUPDR &= ~( 3 << ( 4*2 ) ); // [ 9:8 ] PUPDR4[ 1:0 ] = 0 No pull-up/down om PIN C4 GPIOC->AFR[ 0 ] |= 7 << ( 4*4 );   /* Connect PC5 to USART1_Rx */ GPIOC->MODER |= 2 << (5*2);  // GPIO_Mode_AF GPIOC->AFR[0] |= 7 << (5*4);  //  AF7 } /**************************************************************************************/ void USART1_Configuration(void){   /* USART resources configuration (Clock, GPIO pins and USART registers) ----*/  /* USART configured as follow:        - BaudRate = 9600 baud        - Word Length = 8 Bits        - One Stop Bit        - No parity        - Hardware flow control disabled (RTS and CTS signals)        - Receive and transmit enabled  */  USART1->BRR = 72000000/9600; USART1->CR1 &= ~USART_CR1_OVER8; // Oversampling mode = 16  USART1->CR1 &= ~USART_CR1_M;  // Word length = 8 bits USART1->CR1 &= ~USART_CR1_PCE;  // No parity USART1->CR1 |= USART_CR1_TE;  // Transmitter enable USART1->CR1 |= USART_CR1_RE;  // Receiver enable USART1->CR1 |= USART_CR1_UE;  // USART enable USART1->CR2 &= ~(USART_CR2_STOP_1 | USART_CR2_STOP_0);} /**************************************************************************************/ void OutString(char *s){  while(*s)  {    while(!(USART1->ISR & USART_ISR_TXE)); // Wait for Empty     USART1->TDR =(USART1, *s++);  }} /**************************************************************************************/ int main(void){  RCC_Configuration();   GPIO_Configuration();   USART1_Configuration();   OutString(''This is an echo back test for USART1\r\n'');   while(1) // Don't want to exit  {    uint16_t ch;     while(!(USART1->ISR & USART_ISR_RXNE)); // Wait for Char     ch  = USART1->RDR; // Collect Char     while(!(USART1->ISR & USART_ISR_TXE)); // Wait for Empty     USART1->TDR=(USART1, ch); // Echo Char  }} /**************************************************************************************/ #ifdef  USE_FULL_ASSERT/**  * @brief  Reports the name of the source file and the source line number  *         where the assert_param error has occurred.  * @param  file: pointer to the source file name  * @param  line: assert_param error line source number  * @retval None  */void assert_failed(uint8_t* file, uint32_t line){  /* User can add his own implementation to report the file name and line number,     ex: printf(''Wrong parameters value: file %s on line %d\r\n'', file, line) */   /* Infinite loop */  while (1)  {  }}#endifBut If I try to change it to USART2 and PD5/PD6 does not work. If you can help me would be nice.

[Tesla DeLorean · Accepted solution]

Posted on May 06, 2014 at 04:14

Yes it is valid.

Ok, but what does that construct actually do? But If I try to change it to USART2 and PD5/PD6 does not work. If you can help me would be nice. Could it be that APB1 doesn't run at 72 MHz?

// STM32 USART2 LOOP (Tx PD.5, Rx PD.6) STM32F3xx - sourcer32@gmail.com
#include ''stm32f30x.h''
/**************************************************************************************/
void RCC_Configuration(void)
{
/* Enable GPIO clock */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOD, ENABLE);
/* Enable USART clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
}
/**************************************************************************************/
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* Connect PD5 to USART2_Tx */
GPIO_PinAFConfig(GPIOD, GPIO_PinSource5, GPIO_AF_7);
/* Connect PD6 to USART2_Rx */
GPIO_PinAFConfig(GPIOD, GPIO_PinSource6, GPIO_AF_7);
/* Configure USART Tx/Rx as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOD, &GPIO_InitStructure);
}
/**************************************************************************************/
void USART2_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
/* USART resources configuration (Clock, GPIO pins and USART registers) ----*/
/* USART configured as follow:
- BaudRate = 9600 baud
- Word Length = 8 Bits
- One Stop Bit
- No parity
- Hardware flow control disabled (RTS and CTS signals)
- Receive and transmit enabled
*/
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 configuration */
USART_Init(USART2, &USART_InitStructure);
/* Enable USART */
USART_Cmd(USART2, ENABLE);
}
/**************************************************************************************/
void OutString(char *s)
{
while(*s)
{
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET); // Wait for Empty
USART_SendData(USART2, *s++);
}
}
/**************************************************************************************/
int main(void)
{
RCC_Configuration();
GPIO_Configuration();
USART2_Configuration();
OutString(''This is an echo back test for USART2

'');
while(1) // Don't want to exit
{
uint16_t ch;
while(USART_GetFlagStatus(USART2, USART_FLAG_RXNE) == RESET); // Wait for Char
ch = USART_ReceiveData(USART2); // Collect Char
while(USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET); // Wait for Empty
USART_SendData(USART2, ch); // Echo Char
}
}
/**************************************************************************************/
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf(''Wrong parameters value: file %s on line %d

'', file, line) */
/* Infinite loop */
while (1)
{
}
}
#endif

[definitely]

Posted on May 06, 2014 at 04:22

You are right Clive it was the frequency I changed it to the 36MHz that is needed to work and I did it. Thanks Very Much Man

[Chirag Shah]

Posted on June 02, 2018 at 11:05

I tried the exact same code for PA2->TX, PA3->RX but it doesn't seem to work. The device is stm32f303CB also to view the data I am using a USB to TTL converter and connection of the same is as follows:-

Converter                      STM32

RX               

--------->         TX

TX               

--------->         RX

GND            

--------->         GND

3.3V             --------->         3.3V

The change done by me is as follows:-

GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_7);

/* Connect PD6 to USART2_Rx */GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_7);

GPIO_Init(GPIOA, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;

/* Enable GPIO clock */

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);

I am new to arm based devices do let me know where I might be going wrong.

[Tesla DeLorean]

Posted on June 03, 2018 at 17:52

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