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I have two STM32F407VET6 boards and I want to use one as master and second as slave and connect them with SPI.

I connected the master's SCK to the slave's SCK, master's MOSI to slave's MOSI and slave's NSS to GND.

So this is the master's code and configuration:

    /* USER CODE BEGIN Header */
    /**
      ******************************************************************************
      * @file           : main.c
      * @brief          : Main program body
      ******************************************************************************
      * @attention
      *
      * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
      * All rights reserved.</center></h2>
      *
      * This software component is licensed by ST under BSD 3-Clause license,
      * the "License"; You may not use this file except in compliance with the
      * License. You may obtain a copy of the License at:
      *                        opensource.org/licenses/BSD-3-Clause
      *
      ******************************************************************************
      */
    /* USER CODE END Header */
    /* Includes ------------------------------------------------------------------*/
    #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 ---------------------------------------------------------*/
    I2C_HandleTypeDef hi2c1;
    
    SPI_HandleTypeDef hspi1;
    
    /* USER CODE BEGIN PV */
    
    /* USER CODE END PV */
    
    /* Private function prototypes -----------------------------------------------*/
    void SystemClock_Config(void);
    static void MX_GPIO_Init(void);
    static void MX_SPI1_Init(void);
    static void MX_I2C1_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
      */
    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_SPI1_Init();
      MX_I2C1_Init();
      /* USER CODE BEGIN 2 */
      uint8_t buffer[8];
      for(uint8_t i=0; i<8; i++)
      {
          buffer[i] = i;
      }
      /* USER CODE END 2 */
    
      /* Infinite loop */
      /* USER CODE BEGIN WHILE */
      while (1)
      {
        /* USER CODE END WHILE */
    
        /* USER CODE BEGIN 3 */
    
          HAL_SPI_Transmit(&hspi1, buffer, 8, SPI_TIMEOUT_MAX);
      }
      /* 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_HSE;
      RCC_OscInitStruct.HSEState = RCC_HSE_ON;
      RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
      RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
      RCC_OscInitStruct.PLL.PLLM = 8;
      RCC_OscInitStruct.PLL.PLLN = 336;
      RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
      RCC_OscInitStruct.PLL.PLLQ = 4;
      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_DIV1;
      RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
      RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
    
      if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
      {
        Error_Handler();
      }
    }
    
    /**
      * @brief I2C1 Initialization Function
      * @param None
      * @retval None
      */
    static void MX_I2C1_Init(void)
    {
    
      /* USER CODE BEGIN I2C1_Init 0 */
    
      /* USER CODE END I2C1_Init 0 */
    
      /* USER CODE BEGIN I2C1_Init 1 */
    
      /* USER CODE END I2C1_Init 1 */
      hi2c1.Instance = I2C1;
      hi2c1.Init.ClockSpeed = 100000;
      hi2c1.Init.DutyCycle = I2C_DUTYCYCLE_2;
      hi2c1.Init.OwnAddress1 = 0;
      hi2c1.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
      hi2c1.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
      hi2c1.Init.OwnAddress2 = 0;
      hi2c1.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
      hi2c1.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
      if (HAL_I2C_Init(&hi2c1) != HAL_OK)
      {
        Error_Handler();
      }
      /* USER CODE BEGIN I2C1_Init 2 */
    
      /* USER CODE END I2C1_Init 2 */
    
    }
    
    /**
      * @brief SPI1 Initialization Function
      * @param None
      * @retval None
      */
    static void MX_SPI1_Init(void)
    {
    
      /* USER CODE BEGIN SPI1_Init 0 */
    
      /* USER CODE END SPI1_Init 0 */
    
      /* USER CODE BEGIN SPI1_Init 1 */
    
      /* USER CODE END SPI1_Init 1 */
      /* SPI1 parameter configuration*/
      hspi1.Instance = SPI1;
      hspi1.Init.Mode = SPI_MODE_MASTER;
      hspi1.Init.Direction = SPI_DIRECTION_2LINES;
      hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
      hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
      hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
      hspi1.Init.NSS = SPI_NSS_HARD_OUTPUT;
      hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_4;
      hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
      hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
      hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
      hspi1.Init.CRCPolynomial = 10;
      if (HAL_SPI_Init(&hspi1) != HAL_OK)
      {
        Error_Handler();
      }
      /* USER CODE BEGIN SPI1_Init 2 */
    
      /* USER CODE END SPI1_Init 2 */
    
    }
    
    /**
      * @brief GPIO Initialization Function
      * @param None
      * @retval None
      */
    static void MX_GPIO_Init(void)
    {
    
      /* GPIO Ports Clock Enable */
      __HAL_RCC_GPIOH_CLK_ENABLE();
      __HAL_RCC_GPIOA_CLK_ENABLE();
      __HAL_RCC_GPIOB_CLK_ENABLE();
    
    }
    
    /* 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 */
    }
    
    #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 /* USE_FULL_ASSERT */
    
    /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

And this is the configuration:

enter image description here

As you can see it's the simplest setting with polling method.

Now the slave's code and configuration:

    /* USER CODE BEGIN Header */
    /**
      ******************************************************************************
      * @file           : main.c
      * @brief          : Main program body
      ******************************************************************************
      * @attention
      *
      * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
      * All rights reserved.</center></h2>
      *
      * This software component is licensed by ST under BSD 3-Clause license,
      * the "License"; You may not use this file except in compliance with the
      * License. You may obtain a copy of the License at:
      *                        opensource.org/licenses/BSD-3-Clause
      *
      ******************************************************************************
      */
    /* USER CODE END Header */
    /* Includes ------------------------------------------------------------------*/
    #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 hspi1;
    
    UART_HandleTypeDef huart1;
    
    /* USER CODE BEGIN PV */
    
    /* USER CODE END PV */
    
    /* Private function prototypes -----------------------------------------------*/
    void SystemClock_Config(void);
    static void MX_GPIO_Init(void);
    static void MX_SPI1_Init(void);
    static void MX_USART1_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
      */
    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_SPI1_Init();
      MX_USART1_UART_Init();
      /* USER CODE BEGIN 2 */
    
      /* USER CODE END 2 */
    
      /* Infinite loop */
      /* USER CODE BEGIN WHILE */
      uint8_t buffer[8];
        uint8_t err = 0;
        while (1)
        {
        /* USER CODE END WHILE */
    
        /* USER CODE BEGIN 3 */
            err = HAL_SPI_Receive(&hspi1, buffer, 8, 1000);
            /*while(HAL_SPI_GetState(&hspi1) != HAL_SPI_STATE_READY)
            {
    
            }*/
            HAL_UART_Transmit(&huart1, buffer, 8, 1000);
        }
      /* 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_HSE;
      RCC_OscInitStruct.HSEState = RCC_HSE_ON;
      RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
      RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
      RCC_OscInitStruct.PLL.PLLM = 4;
      RCC_OscInitStruct.PLL.PLLN = 168;
      RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
      RCC_OscInitStruct.PLL.PLLQ = 4;
      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_DIV1;
      RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
      RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
    
      if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
      {
        Error_Handler();
      }
    }
    
    /**
      * @brief SPI1 Initialization Function
      * @param None
      * @retval None
      */
    static void MX_SPI1_Init(void)
    {
    
      /* USER CODE BEGIN SPI1_Init 0 */
    
      /* USER CODE END SPI1_Init 0 */
    
      /* USER CODE BEGIN SPI1_Init 1 */
    
      /* USER CODE END SPI1_Init 1 */
      /* SPI1 parameter configuration*/
      hspi1.Instance = SPI1;
      hspi1.Init.Mode = SPI_MODE_SLAVE;
      hspi1.Init.Direction = SPI_DIRECTION_2LINES_RXONLY;
      hspi1.Init.DataSize = SPI_DATASIZE_8BIT;
      hspi1.Init.CLKPolarity = SPI_POLARITY_LOW;
      hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
      hspi1.Init.NSS = SPI_NSS_SOFT;
      hspi1.Init.FirstBit = SPI_FIRSTBIT_MSB;
      hspi1.Init.TIMode = SPI_TIMODE_DISABLE;
      hspi1.Init.CRCCalculation = SPI_CRCCALCULATION_DISABLE;
      hspi1.Init.CRCPolynomial = 10;
      if (HAL_SPI_Init(&hspi1) != HAL_OK)
      {
        Error_Handler();
      }
      /* USER CODE BEGIN SPI1_Init 2 */
    
      /* USER CODE END SPI1_Init 2 */
    
    }
    
    /**
      * @brief USART1 Initialization Function
      * @param None
      * @retval None
      */
    static void MX_USART1_UART_Init(void)
    {
    
      /* USER CODE BEGIN USART1_Init 0 */
    
      /* USER CODE END USART1_Init 0 */
    
      /* USER CODE BEGIN USART1_Init 1 */
    
      /* USER CODE END USART1_Init 1 */
      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();
      }
      /* USER CODE BEGIN USART1_Init 2 */
    
      /* USER CODE END USART1_Init 2 */
    
    }
    
    /**
      * @brief GPIO Initialization Function
      * @param None
      * @retval None
      */
    static void MX_GPIO_Init(void)
    {
    
      /* GPIO Ports Clock Enable */
      __HAL_RCC_GPIOH_CLK_ENABLE();
      __HAL_RCC_GPIOA_CLK_ENABLE();
    
    }
    
    /* 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 */
    }
    
    #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 /* USE_FULL_ASSERT */
    
    /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

enter image description here

The return value of err is always HAL_OK on both sides.

The problem is that I'm getting shifted values in slave's buffer or the data is not correct.

I've commented

    while(HAL_SPI_GetState(&hspi1) != HAL_SPI_STATE_READY)
                {
        
                }

because it does not affects at all.

Also I tried to use the NSS pin for master and Hardware NSS input signal for slave, but same result.

What I'm doing wrong?

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1 Answer 1

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The code just does what it does and the result is as expected from that code.

The code does continuous transmission and reception of bytes without any syncronization at all.

There is nothing to syncronize that the transmission and reception would be in sync, not for bytes, and noto even for bits if you don't use the NSS signal.

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3
  • \$\begingroup\$ Now I'm using NSS signal, with software togglin and also with Hardware toggling, but without result. How can I sync Master and Slave? \$\endgroup\$
    – Alatriste
    Commented Dec 18, 2021 at 18:06
  • \$\begingroup\$ @Alatriste that is a whole new and complex question. How to syncronize them would require knowledge what you are trying to do and why. \$\endgroup\$
    – Justme
    Commented Dec 18, 2021 at 18:18
  • \$\begingroup\$ I'll try to do it with Full duplex master/slave modes and ACK signals. \$\endgroup\$
    – Alatriste
    Commented Dec 18, 2021 at 18:31

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