UART IN STM32F4-DISCOVERY BOARD

[13bec078]

Posted on August 26, 2016 at 14:48

I am trying to send data (a string ''hello'') serially to my PC from STM32f4Discovery board and HC-05 (bluetooth module) using UART. I generated the following code using the STM32cubemx software. The code was successfully built and dumped using keil IDE. But meaningless data was being received instead of the desired ''hello'' while observing via TERA TERM. I set the buad rate as 9600. 

Someone please help!! :( 

 #include ''stm32f4xx_hal.h''

UART_HandleTypeDef huart1;

void SystemClock_Config(void);

void Error_Handler(void);

static void MX_GPIO_Init(void);

static void MX_USART1_UART_Init(void);

#ifdef __GNUC__

  

  #define PUTCHAR_PROTOTYPE int __io_putchar(int ch)

#else

  #define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)

#endif 

PUTCHAR_PROTOTYPE

{

HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 100);

return ch;

}

int main(void)

{

  HAL_Init();

  SystemClock_Config();

  MX_GPIO_Init();

  MX_USART1_UART_Init();

  while (1)

  {

  printf(''hello\r\n'');

  HAL_Delay(500);

  }

}

void SystemClock_Config(void)

{

  RCC_OscInitTypeDef RCC_OscInitStruct;

  RCC_ClkInitTypeDef RCC_ClkInitStruct;

  __HAL_RCC_PWR_CLK_ENABLE();

  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;

  RCC_OscInitStruct.HSIState = RCC_HSI_ON;

  RCC_OscInitStruct.HSICalibrationValue = 16;

  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;

  RCC_OscInitStruct.PLL.PLLM = 8;

  RCC_OscInitStruct.PLL.PLLN = 50;

  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;

  RCC_OscInitStruct.PLL.PLLQ = 7;

  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

  {

    Error_Handler();

  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK

                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;

  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;

  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;

  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV8;

  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV4;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)

  {

    Error_Handler();

  }

  HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

  HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

  HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);

}

static void MX_USART1_UART_Init(void)

{

  huart1.Instance = USART1;

  huart1.Init.BaudRate = 9600;

  huart1.Init.WordLength = UART_WORDLENGTH_8B;

  huart1.Init.StopBits = UART_STOPBITS_1;

  huart1.Init.Parity = UART_PARITY_NONE;

  huart1.Init.Mode = UART_MODE_TX_RX;

  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;

  huart1.Init.OverSampling = UART_OVERSAMPLING_16;

  if (HAL_UART_Init(&huart1) != HAL_OK)

  {

    Error_Handler();

  }

}

static void MX_GPIO_Init(void)

{

  GPIO_InitTypeDef GPIO_InitStruct;

  __HAL_RCC_GPIOA_CLK_ENABLE();

  __HAL_RCC_GPIOC_CLK_ENABLE();

  GPIO_InitStruct.Pin = GPIO_PIN_0;

  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;

  GPIO_InitStruct.Pull = GPIO_NOPULL;

  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = GPIO_PIN_9;

  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

  GPIO_InitStruct.Pull = GPIO_NOPULL;

  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  GPIO_InitStruct.Pin = GPIO_PIN_8;

  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

  GPIO_InitStruct.Pull = GPIO_NOPULL;

  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  HAL_GPIO_WritePin(GPIOC, GPIO_PIN_9, GPIO_PIN_RESET);

  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);

}

void Error_Handler(void)

{

  while(1) 

  {

  }

}

#ifdef USE_FULL_ASSERT

void assert_failed(uint8_t* file, uint32_t line)

{

}

#endif

[sherman]

Posted on August 31, 2016 at 01:49

Are you viewing the string in memory to verify that ''hello'' is in the correct format?  Once you verify the correct string is being transmitted, you can troubleshoot down the line.

[aaron239955_stm1_st]

Posted on September 02, 2016 at 17:20

If you're getting an ''h'' and then nothing on TeraTerm it may be because your character output routine does not check that the UART is ready to take another character.  If you change the HAL call to something like this:

while(HAL_UART_Transmit(&huart1,(uint8_t*)&ch,1,100) != HAL_OK);

it will spin until the HAL transmit routine is ready for another transaction.  Otherwise the HAL call will fail, your putchar routine will return to printf() and nothing will have been sent.

[Tesla DeLorean]

Posted on September 02, 2016 at 17:31

Your clock settings are rather odd. If you want the processor at 25 MHz, the AHB/APB dividers can all be DIV1. The power savings from going lower doesn't really outweigh diminished flexibility/functionality of the peripherals.

Which pins is USART1 using? On the STM32F4-DISCO the PA9 pin really isn't usable for USART1