UART NOT Transmit if there is a delay in while loop

[ARehm]

Hi,

I generated the code through CUBEMAX, using USART3 with DMA and trying to send couple of bytes by call HAL_UART_Transmit_DMA in main while(1) loop. If I add the delay after a transmission even a 1ms it stop transmitting but if I remove the delay it start transmitting.

HERE is code:

/* Includes ------------------------------------------------------------------*/

#include "main.h"

#include <string.h>

/* Private includes ----------------------------------------------------------*/

/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/

/* USER CODE BEGIN PTD */

#define MB_PER_SEC_1 1000000

#define HOST_RADIO_SHDN_Pin GPIO_PIN_5

#define HOST_RADIO_SHDN_GPIO_Port GPIOD

/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/

/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/

/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

UART_HandleTypeDef huart3;

DMA_HandleTypeDef hdma_usart3_rx;

DMA_HandleTypeDef hdma_usart3_tx;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/

void SystemClock_Config(void);

static void MX_GPIO_Init(void);

static void MX_DMA_Init(void);

static void MX_USART3_UART_Init(void);

/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/

/* USER CODE BEGIN 0 */

/* USER CODE END 0 */

/**

 * @brief The application entry point.

 * @retval int

 */

uint8_t data[] = {0x7E ,0x44 ,0x00 ,0x85 ,0x26 ,0x00 ,0x00 ,0x00 ,0x00 ,0x00 ,0x04 ,0x00, 0x31, 0x32 ,0x30, 0x00,0xFF};

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_DMA_Init();

 MX_USART3_UART_Init();

 /* USER CODE BEGIN 2 */

HAL_GPIO_WritePin(HOST_RADIO_SHDN_GPIO_Port, HOST_RADIO_SHDN_Pin, GPIO_PIN_SET);

HAL_Delay(100);

HAL_GPIO_WritePin(HOST_RADIO_SHDN_GPIO_Port, HOST_RADIO_SHDN_Pin, GPIO_PIN_RESET);

 /* USER CODE END 2 */

HAL_Delay(5000);

 /* Infinite loop */

 /* USER CODE BEGIN WHILE */

 while(1){

 if(HAL_UART_Transmit_DMA(&huart3, data, strlen((char*)data) - 1) != HAL_OK)

 {

 Error_Handler();

 }

 HAL_Delay(5000);

 }

 /* USER CODE END 3 */

}

/**

 * @brief System Clock Configuration

 * @retval None

 */

void SystemClock_Config(void)

{

 RCC_OscInitTypeDef RCC_OscInitStruct = {0};

 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

 RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};

 /** Initializes the CPU, AHB and APB busses clocks 

 */

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSI;

 RCC_OscInitStruct.MSIState = RCC_MSI_ON;

 RCC_OscInitStruct.MSICalibrationValue = 0;

 RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;

 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_MSI;

 RCC_OscInitStruct.PLL.PLLM = 1;

 RCC_OscInitStruct.PLL.PLLN = 40;

 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;

 RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;

 RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;

 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

 {

  Error_Handler();

 }

 /** 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_PLLCLK;

 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_4) != HAL_OK)

 {

  Error_Handler();

 }

 PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART3;

 PeriphClkInit.Usart3ClockSelection = RCC_USART3CLKSOURCE_PCLK1;

 if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)

 {

  Error_Handler();

 }

 /** Configure the main internal regulator output voltage 

 */

 if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1) != HAL_OK)

 {

  Error_Handler();

 }

}

/**

 * @brief USART3 Initialization Function

 * @param None

 * @retval None

 */

static void MX_USART3_UART_Init(void)

{

 /* USER CODE BEGIN USART3_Init 0 */

 /* USER CODE END USART3_Init 0 */

 /* USER CODE BEGIN USART3_Init 1 */

 /* USER CODE END USART3_Init 1 */

 huart3.Instance = USART3;

 huart3.Init.BaudRate = 1000000;

 huart3.Init.WordLength = UART_WORDLENGTH_8B;

 huart3.Init.StopBits = UART_STOPBITS_1;

 huart3.Init.Parity = UART_PARITY_NONE;

 huart3.Init.Mode = UART_MODE_TX_RX;

 huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;//UART_HWCONTROL_RTS_CTS;

 huart3.Init.OverSampling = UART_OVERSAMPLING_16;

 huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;

 huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;

 if (HAL_UART_Init(&huart3) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN USART3_Init 2 */

 /* USER CODE END USART3_Init 2 */

}

/** 

 * Enable DMA controller clock

 */

static void MX_DMA_Init(void) 

{

 /* DMA controller clock enable */

 __HAL_RCC_DMA1_CLK_ENABLE();

 /* DMA interrupt init */

 /* DMA1_Channel2_IRQn interrupt configuration */

 HAL_NVIC_SetPriority(DMA1_Channel2_IRQn, 0, 0);

 HAL_NVIC_EnableIRQ(DMA1_Channel2_IRQn);

 /* DMA1_Channel3_IRQn interrupt configuration */

 HAL_NVIC_SetPriority(DMA1_Channel3_IRQn, 0, 0);

 HAL_NVIC_EnableIRQ(DMA1_Channel3_IRQn);

}

/**

 * @brief GPIO Initialization Function

 * @param None

 * @retval None

 */

static void MX_GPIO_Init(void)

{

GPIO_InitTypeDef GPIO_InitStruct = {0};

 /* GPIO Ports Clock Enable */

 __HAL_RCC_GPIOC_CLK_ENABLE();

 __HAL_RCC_GPIOH_CLK_ENABLE();

 __HAL_RCC_GPIOB_CLK_ENABLE();

 __HAL_RCC_GPIOD_CLK_ENABLE();

 __HAL_RCC_GPIOA_CLK_ENABLE();

 /*Configure GPIO pin : HOST_RADIO_SHDN_Pin */

  GPIO_InitStruct.Pin = HOST_RADIO_SHDN_Pin;

  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;

  GPIO_InitStruct.Pull = GPIO_NOPULL;

  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;

  HAL_GPIO_Init(HOST_RADIO_SHDN_GPIO_Port, &GPIO_InitStruct);

}

[waclawek.jan]

Stop execution in debugger and find out what does the processor do. Read out and check the DMA and UART registers content.

JW

[S.Ma]

Understand what the HAL function does: is it blocking? if not, what function tells you when the transfer is completed (instead of a crude delay)...