Electrical – STM32 HAL Implementing UART receive Interrupt

hal-librarystm32

I have trouble in implementing the USART RX on a stm32f303k8t6 with the HAL libraries. What I actually want to achieve is, that I can send a variable length string over the uart bus and decode the string, which is actually a key/value pair. What I have tried so far is the following: I receive an interrupt for every received character and as long it is not a '$' sign, it is loading a buffer. But somehow the interrupt function is only called once, and I don't get why. I would anyway like to use the callback functions from HAL, but they never get called.

stm32f3xx_it.c

void USART1_IRQHandler(void)
{
    /* USER CODE BEGIN USART1_IRQn 0 */
    if (USART1->ISR & UART_IT_RXNE) {
        isRx=1;
    }
    /* USER CODE END USART1_IRQn 0 */
    HAL_UART_IRQHandler(&huart1);
    /* USER CODE BEGIN USART1_IRQn 1 */
    if(isRx) {
        uint8_t rbyte = huart1.Instance->RDR;
        __HAL_UART_SEND_REQ(&huart1, UART_RXDATA_FLUSH_REQUEST);
        rx_data[pointer]=rbyte;
        if(rx_data[pointer]=='$') {
              rx_data[pointer]='\0';
              pointer=0;
              copyValuesToBuff();
              clearBuffer(&rx_data,32);
        } else {
          pointer++;
          if(pointer>=32) {
              pointer=0;
          }
        }
        __HAL_UART_ENABLE_IT(&huart1,UART_IT_RXNE);
    }

}

main.c

#include "main.h"
    #include "stm32f3xx_hal.h"

    /* USER CODE BEGIN Includes */
    #include "USART.h"

    /* USER CODE END Includes */

    /* Private variables ---------------------------------------------------------*/
    UART_HandleTypeDef huart1;

    /* USER CODE BEGIN PV */
    /* Private variables ---------------------------------------------------------*/
    char rx_buff[32];
    char rx_data[32];
    /* USER CODE END PV */
    uint8_t aRxBuffer[10];
    /* Private function prototypes -----------------------------------------------*/
    void SystemClock_Config(void);
    static void MX_GPIO_Init(void);
    static void MX_USART1_UART_Init(void);

    /* USER CODE BEGIN PFP */
    /* Private function prototypes -----------------------------------------------*/

    /* USER CODE END PFP */

    /* USER CODE BEGIN 0 */

    /* USER CODE END 0 */

    int main(void)
    {

    /* USER CODE BEGIN 1 */

    /* USER CODE END 1 */

    /* MCU Configuration----------------------------------------------------------*/

    /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
    HAL_Init();

    /* USER CODE BEGIN Init */

    /* USER CODE END Init */

    /* Configure the system clock */
    SystemClock_Config();

    /* USER CODE BEGIN SysInit */

    /* USER CODE END SysInit */

    /* Initialize all configured peripherals */
    MX_GPIO_Init();
    MX_USART1_UART_Init();

    /* USER CODE BEGIN 2 */
    //__HAL_UART_ENABLE_IT(&huart1,UART_IT_RXNE);
    HAL_UART_Receive_IT(&huart1, (uint8_t *)aRxBuffer, 10);
    /* USER CODE END 2 */

    /* Infinite loop */
    /* USER CODE BEGIN WHILE */
    while (1)
    {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */

    }
    /* USER CODE END 3 */

    }

    /** System Clock Configuration
    */
    void SystemClock_Config(void)
    {

    RCC_OscInitTypeDef RCC_OscInitStruct;
    RCC_ClkInitTypeDef RCC_ClkInitStruct;
    RCC_PeriphCLKInitTypeDef PeriphClkInit;

    /**Initializes the CPU, AHB and APB busses clocks
    */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
    RCC_OscInitStruct.HSIState = RCC_HSI_ON;
    RCC_OscInitStruct.HSICalibrationValue = 16;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
    _Error_Handler(__FILE__, __LINE__);
    }

    /**Initializes the CPU, AHB and APB busses clocks
    */
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
    {
    _Error_Handler(__FILE__, __LINE__);
    }

    PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1;
    PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK1;
    if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
    {
    _Error_Handler(__FILE__, __LINE__);
    }

    /**Configure the Systick interrupt time
    */
    HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);

    /**Configure the Systick
    */
    HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);

    /* SysTick_IRQn interrupt configuration */
    HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);
    }

    /* USART1 init function */
    static void MX_USART1_UART_Init(void)
    {

    huart1.Instance = USART1;
    huart1.Init.BaudRate = 57600;
    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;
    huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
    huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
    if (HAL_UART_Init(&huart1) != HAL_OK)
    {
    _Error_Handler(__FILE__, __LINE__);
    }

    }

    /** Pinout Configuration
    */
    static void MX_GPIO_Init(void)
    {

    /* GPIO Ports Clock Enable */
    __HAL_RCC_GPIOA_CLK_ENABLE();

    }

    /* USER CODE BEGIN 4 */
    void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart) {

    }
    /* USER CODE END 4 */

    /**
    * @brief  This function is executed in case of error occurrence.
    * @param  None
    * @retval None
    */
    void _Error_Handler(char * file, int line)
    {
    /* USER CODE BEGIN Error_Handler_Debug */
    /* User can add his own implementation to report the HAL error return state */
    while(1)
    {
    }
    /* USER CODE END Error_Handler_Debug */
    }

    #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 CODE BEGIN 6 */
    /* 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) */
    /* USER CODE END 6 */

    }

    #endif

Best Answer

With a quick glance I see two potential issues. 1. You need to put the HAL_UART_Receive_ITinside the super loop. 2. The IRQ handler needs to be kept short. What you want to do is put the code in the HAL_UART_RxCpltCallback function which is going to be run after every RX.

It is a good idea to just try to use some the STM32 Cube examples.

Related Solutions

Electronic – STM32 DMA Transfer bridge between 2 uart ports

Consider the following snippet from the STM32F1 manual regarding the USART data register and its corresponding status bit 'TXE':

Single byte communication

The TXE bit is always cleared by a write to the data register. The TXE bit is set by hardware and it indicates:

• The data has been moved from TDR to the shift register and the data transmission has started.

• The TDR register is empty.

• The next data can be written in the USART_DR register without overwriting the previous data.

This flag generates an interrupt if the TXEIE bit is set.

Can you imagine a scenario where you are writing into the data register before the previous byte has made it into the shift register? Think about the sequence of events when you receive a stream of bytes, especially when you receive the third or fourth byte, what is your transmitter doing at this point? Is its data register occupied?

As a previous comment mentioned, you likely need a way to buffer previous byte(s) if the TXE status bit is not set. Writing into the USART data register while the TXE status bit is not set is a guaranteed way to lose information.

Edit in response to comment:

That's one way to do it, I would imagine it would work. However, I think doing away with DMA and using the USART interrupts would be a better approach. You can have 2 interrupt service routines for when a byte is received and when the transmit data register is empty. Based on those two events, you can decide to buffer the data (in the RX handler) and to empty the buffer (in TX complete handler). Care must be taken in deciding when to enable/disable the TX complete interrupt. I think the overhead of setting up DMA makes more sense for larger sequential transactions into (or out of) buffers, and less so for the single byte-by-byte case.

Electronic – STM32 HAL UART Transmit DMA problem

First of all I can't get the stm to transmit at baud rates higher then the standard 115200, according to the datasheets both the FT2232H and the STM32F7 should be capable of at least 12M baud.

The hardware supports speeds up to 27 Mbit (well, you haven't told your part number, I'm looking at the F756 datasheet), but according to stm32f7xx_hal_uart.h, HAL won't accept a speed above 9M

#define IS_UART_BAUDRATE(BAUDRATE) ((BAUDRATE) < 9000001)

Moreover, it depends on the system clock speed, in the default configuration, when you don't touch the Clock Configuration tab in STM32CubeMX, everything operates on the 16 MHz internal HSI clock. That means at most 1 Mbit while you are using UART_OVERSAMPLING_16, or twice that if you switch to UART_OVERSAMPLING_8 (but then you'd lose noise detection).

Second is that I can't call the sendUART() function multiple times in a row, why isn't the DMA Fifo used to store the stuff I want to send?

Although there is a 16 byte DMA FIFO, it's not accessible to the software. There is no way to just append some more data to an ongoing DMA transfer. HAL does nothing but starts a DMA transfer from the buffer address supplied by the caller.

You have to wait until the transfer is finished, or suspend DMA, and still wait until the FIFO is empty. You can of course allocate a buffer yourself, add data as it comes, and restart DMA whenever it finishes and there is new data in the buffer.

Also whats the right way to echo back all received data but make use of the fifo so no data is lost when it's not polled in time?

It looks like to me, that you can't have both DMA and interrupts on every received character. At least, the ISR status register value would be useless, and the interrupt handler won't be able to decide what to do. Reading it could even interfere with the DMA transfer. Therefore, you must choose one.

Using DMA to put the data in a buffer (or two), you can then poll the transfer counter regularly in the idle loop or a timer interrupt. There won't be an immediate response, but it'd perhaps not matter at all, because the USB interface would incur some delay too.

Best Answer

Related Solutions

Electronic – STM32 DMA Transfer bridge between 2 uart ports

Electronic – STM32 HAL UART Transmit DMA problem

Related Topic