STM32 discovery board serial (RS232) communication

[markhaslehurst]

Posted on February 23, 2011 at 18:01

I have just got one of these boards, but as a noob, I am really struggling to get the USART working. I want to display information on the computer. I understand that the ST_LINK cannot do UART over the built in USB cable (ITM Debug). Is this correct?

So.. I have been looking at pins PA9 and PA10, but cannot see anything coming out. I have the following code. Could someone please take a look and see if they can see my problem?? I have spent hours on this! Thanks all! code: &sharpinclude ''stm32F10x.h'' &sharpinclude ''STM32vldiscovery.h'' &sharpinclude ''stm32f10x_usart.h'' &sharpinclude ''stm32f10x_rcc.h'' &sharpinclude <stdio.h> &sharpdefine  LSE_FAIL_FLAG  0x80 &sharpdefine  LSE_PASS_FLAG  0x100

void Delay(uint32_t nTime);

int main(void)

{  initAll();  while(1)  {  } }

void initGPIO (void)

{   /* Enable GPIOx Clock */   RCC_APB1PeriphClockCmd(RCC_APB1Periph_PWR, ENABLE);     /* Initialise LEDs LD3&LD4, both off */   STM32vldiscovery_LEDInit(LED3);   STM32vldiscovery_LEDInit(LED4);     STM32vldiscovery_LEDOff(LED3);   STM32vldiscovery_LEDOff(LED4);     /* Initialise USER Button */   STM32vldiscovery_PBInit(BUTTON_USER, BUTTON_MODE_EXTI); }

void initSysTick (void)

{  /* Setup SysTick Timer for 1 msec interrupts  */  if (SysTick_Config(SystemCoreClock / 1000))  {   /* Capture error */   while (1);  } }

void initLSE (void)

{  /* Enable access to the backup register => LSE can be enabled */  PWR_BackupAccessCmd(ENABLE);    /* Enable LSE (Low Speed External Oscillation) */  RCC_LSEConfig(RCC_LSE_ON);    /* Check the LSE Status */  while(1)  {   if(LSE_Delay < LSE_FAIL_FLAG)   {    /* check whether LSE is ready, with 4 seconds timeout */    Delay (500);    LSE_Delay += 0x10;    if(RCC_GetFlagStatus(RCC_FLAG_LSERDY) != RESET)    {     /* Set flag: LSE PASS */     LSE_Delay |= LSE_PASS_FLAG;     /* Turn Off Led4 */     STM32vldiscovery_LEDOff(LED4);     /* Disable LSE */     RCC_LSEConfig(RCC_LSE_OFF);     break;    }          }   else /*if(LSE_Delay >= LSE_FAIL_FLAG)*/ /* LSE_FAIL_FLAG = 0x80 */    {             if(RCC_GetFlagStatus(RCC_FLAG_LSERDY) == RESET)    {     /* Set flag: LSE FAIL */     LSE_Delay |= LSE_FAIL_FLAG;     /* Turn On Led4 */     STM32vldiscovery_LEDOn(LED4);    }           /* Disable LSE */    RCC_LSEConfig(RCC_LSE_OFF);    break;   }  } } void initUART (void) {  GPIO_InitTypeDef GPIO_InitStructureTx;  GPIO_InitTypeDef GPIO_InitStructureRx;  USART_InitTypeDef USART_InitStructure;

 RCC_APB1PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);  // Enable clocks

 GPIO_InitStructureTx.GPIO_Pin = GPIO_Pin_9;                // Configure TX pin

 GPIO_InitStructureTx.GPIO_Mode = GPIO_Mode_AF_PP;              // Push-Pull  GPIO_InitStructureTx.GPIO_Speed = GPIO_Speed_2MHz;              // 50MHz  GPIO_Init(GPIOA, &GPIO_InitStructureTx);                // Initialise

 GPIO_InitStructureRx.GPIO_Pin = GPIO_Pin_10;               // Configure RX pin

 GPIO_InitStructureRx.GPIO_Mode = GPIO_Mode_IN_FLOATING;             // Push-Pull  GPIO_InitStructureRx.GPIO_Speed = GPIO_Speed_2MHz;              // 50MHz  GPIO_Init(GPIOA, &GPIO_InitStructureRx);                // Iniitialise

 USART_InitStructure.USART_BaudRate = 57600;                // Set USART1 Baud Rate

    USART_InitStructure.USART_WordLength = USART_WordLength_8b;            // Set USART1 Word Length     USART_InitStructure.USART_StopBits = USART_StopBits_1;             // Configure USART1 Stop Bits     USART_InitStructure.USART_Parity = USART_Parity_No;              // Configure USART1 Parity Bits     USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;       // Configure USART1 Flow Control     USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;           // Set USART1 Operation Mode

 USART_Init(USART1, &USART_InitStructure);                // Configure UART

 USART_Cmd(USART1, ENABLE);                    // Enable UART

 //setvbuf(stdout, NULL, _IONBF, 0);

    //printf(''USART1 Inisialised\n'');  USART_SendData(USART1, 'c');  //while (!(USART1->SR & USART_FLAG_TXE));     //USART1->DR = (0x35);

}

void initAll (void)

{  initGPIO();  initSysTick();  initLSE();  initUART(); } There is also a file which provides the delay procedure, using the SysTick. Thanks for any help or guidance! #stm32 #discovery #usart #rs232

[Tesla DeLorean]

Posted on February 24, 2011 at 01:28

RCC_APB1PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);  // Enable clocks

RCC_APB2PeriphClockCmd(); Perhaps?

[markhaslehurst]

Posted on February 24, 2011 at 10:14

Hi. Thanks for your reply! That seems to have helped a lot!

Now that I look closer at the arguments being passed, that does seem to make sense!