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F407 Transmits Garbage values after the message via SPI

Geetansh
Associate II

I was working on a simple SPI transmit code, I am transmitting some string data via SPI Half duplex, the code is like I press blue button on the discovery board, and it transmits data, which I read from logic analyzer, but every time after data is transmitted, and I keep button pressed/release and press again, it also sends some garbage values after that, and keeps on doing that, I can't figure out what's wrong, pls find Code and Analyzer traces below

*******************************CODE BELOW***********************************

#include "main.h"

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

/* USER CODE BEGIN Includes */

/* USER CODE END Includes */

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

/* USER CODE BEGIN PTD */

/* 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 ---------------------------------------------------------*/

SPI_HandleTypeDef hspi3;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

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

void SystemClock_Config(void);

static void MX_GPIO_Init(void);

static void MX_SPI3_Init(void);

/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

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

/* USER CODE BEGIN 0 */

uint8_t Dat[] = "Sample data transmit";

/* USER CODE END 0 */

/**

 * @brief The application entry point.

 * @retval int

 */

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_SPI3_Init();

 /* USER CODE BEGIN 2 */

 /* USER CODE END 2 */

 /* Infinite loop */

 /* USER CODE BEGIN WHILE */

 while (1)

 {

if(HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0)==GPIO_PIN_SET)

{

HAL_SPI_Transmit(&hspi3, (uint8_t*)&Dat, sizeof(Dat), 100);

HAL_Delay(10);

}

  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */

 }

 /* USER CODE END 3 */

}

/**

 * @brief System Clock Configuration

 * @retval None

 */

void SystemClock_Config(void)

{

 RCC_OscInitTypeDef RCC_OscInitStruct = {0};

 RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

 /** Configure the main internal regulator output voltage

 */

 __HAL_RCC_PWR_CLK_ENABLE();

 __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

 /** Initializes the RCC Oscillators according to the specified parameters

 * in the RCC_OscInitTypeDef structure.

 */

 RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;

 RCC_OscInitStruct.HSIState = RCC_HSI_ON;

 RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;

 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;

 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;

 RCC_OscInitStruct.PLL.PLLM = 8;

 RCC_OscInitStruct.PLL.PLLN = 64;

 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;

 RCC_OscInitStruct.PLL.PLLQ = 7;

 if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)

 {

  Error_Handler();

 }

 /** Initializes the CPU, AHB and APB buses 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_DIV64;

 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;

 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

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

 {

  Error_Handler();

 }

}

/**

 * @brief SPI3 Initialization Function

 * @param None

 * @retval None

 */

static void MX_SPI3_Init(void)

{

 /* USER CODE BEGIN SPI3_Init 0 */

 /* USER CODE END SPI3_Init 0 */

 /* USER CODE BEGIN SPI3_Init 1 */

 /* USER CODE END SPI3_Init 1 */

 /* SPI3 parameter configuration*/

 hspi3.Instance = SPI3;

 hspi3.Init.Mode = SPI_MODE_MASTER;

 hspi3.Init.Direction = SPI_DIRECTION_1LINE;

 hspi3.Init.DataSize = SPI_DATASIZE_8BIT;

 hspi3.Init.CLKPolarity = SPI_POLARITY_LOW;

 hspi3.Init.CLKPhase = SPI_PHASE_1EDGE;

 hspi3.Init.NSS = SPI_NSS_SOFT;

 hspi3.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_2;

 hspi3.Init.FirstBit = SPI_FIRSTBIT_MSB;

 hspi3.Init.TIMode = SPI_TIMODE_DISABLE;

 hspi3.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;

 hspi3.Init.CRCPolynomial = 10;

 if (HAL_SPI_Init(&hspi3) != HAL_OK)

 {

  Error_Handler();

 }

 /* USER CODE BEGIN SPI3_Init 2 */

 /* USER CODE END SPI3_Init 2 */

}

/**

 * @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_GPIOH_CLK_ENABLE();

 __HAL_RCC_GPIOA_CLK_ENABLE();

 __HAL_RCC_GPIOC_CLK_ENABLE();

 __HAL_RCC_GPIOB_CLK_ENABLE();

 /*Configure GPIO pin : PA0 */

 GPIO_InitStruct.Pin = GPIO_PIN_0;

 GPIO_InitStruct.Mode = GPIO_MODE_INPUT;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

 /*Configure GPIO pins : PB3 PB5 */

 GPIO_InitStruct.Pin = GPIO_PIN_3|GPIO_PIN_5;

 GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;

 GPIO_InitStruct.Pull = GPIO_NOPULL;

 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;

 GPIO_InitStruct.Alternate = GPIO_AF5_SPI1;

 HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**

 * @brief This function is executed in case of error occurrence.

 * @retval None

 */

void Error_Handler(void)

{

 /* USER CODE BEGIN Error_Handler_Debug */

 /* User can add his own implementation to report the HAL error return state */

 __disable_irq();

 while (1)

 {

 }

 /* USER CODE END Error_Handler_Debug */

}

0693W00000QKJv5QAH.png0693W00000QKJv0QAH.png

1 ACCEPTED SOLUTION

Accepted Solutions

I wouldn't call it buggy. It is simply not intended for precise timing required by bidir SPI.

Maybe it's better to avoid bidir (halfduplex) SPI at all, if that's an option.

JW

View solution in original post

5 REPLIES 5

> SPI Half duplex

> it also sends some garbage values after that,

If you mean extra clocks after data have been transmitted, it may be SPI being turned to Rx before disabled, in the HAL function. I don't use Cube/HAL and am not interested, you can look it up if you want, Cube/HAL is open source.

JW

If i remember correctly, HAL_SPI_Transmit disable SPI after transmission. SPI output lines become HiZ. Logic analyzer can't reand HiZ lines correctly and can't be trusted. If you need, check output by oscilloscope to confirm that. If you need, you can equip your SPI lines by pullup/pulldown (you can use embedded resistor on MCU), or you can throw away HAL and manage SPI transfer by LL API or by direct register acces. If your slave device have CS pin, then you probably have no problem with that (nobody don't care about SCK and MISO if not addresed by CS).

Thanks for the suggestion, i will definitely look forward to it

Sure, i think you are somewhat correct about HAL, it seems that code is buggy

I wouldn't call it buggy. It is simply not intended for precise timing required by bidir SPI.

Maybe it's better to avoid bidir (halfduplex) SPI at all, if that's an option.

JW