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How to Convert UART received data into Float

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suriya
Associate II

‎2023-09-02 12:13 AM

HI

"I am using an STM32G071CBT6 controller, and I am receiving data using the receive interrupt. I have received some values in my buffer memory, and now I want to convert them to float. If you have any examples, please share them. My buffer memory is of type uint8_t rx_data[1]

 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include<string.h>
#include<stdio.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 ---------------------------------------------------------*/
ADC_HandleTypeDef hadc1;
 
DAC_HandleTypeDef hdac1;
 
UART_HandleTypeDef huart3;
 
uint8_t txbuf[64]= "Welcome\n\r";
uint8_t rx_data[1];
 
/* USER CODE BEGIN PV */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
 /* Prevent unused argument(s) compilation warning */
 UNUSED(huart);
 
 /* NOTE : This function should not be modified, when the callback is needed,
           the HAL_UART_RxCpltCallback can be implemented in the user file.
  */
 HAL_UART_Receive_IT(&huart3, rx_data, sizeof(rx_data));
 HAL_UART_Transmit(&huart3, rx_data,sizeof(rx_data), 10);
 
 
}
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_ADC1_Init(void);
static void MX_USART3_UART_Init(void);
static void MX_DAC1_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_ADC1_Init();
  MX_USART3_UART_Init();
  MX_DAC1_Init();
  /* USER CODE BEGIN 2 */
 
  HAL_UART_Transmit(&huart3, txbuf, sizeof(txbuf), 100);
  HAL_UART_Receive_IT(&huart3, rx_data, sizeof(rx_data));
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
   {
 
 
      }
  }
 
/**
  * @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_PWREx_ControlVoltageScaling(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.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  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 buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief ADC1 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_ADC1_Init(void)
{
 
  /* USER CODE BEGIN ADC1_Init 0 */
 
  /* USER CODE END ADC1_Init 0 */
 
  ADC_ChannelConfTypeDef sConfig = {0};
 
  /* USER CODE BEGIN ADC1_Init 1 */
 
  /* USER CODE END ADC1_Init 1 */
 
  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
  */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV4;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
  hadc1.Init.ScanConvMode = ADC_SCAN_ENABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.LowPowerAutoPowerOff = DISABLE;
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.DMAContinuousRequests = DISABLE;
  hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
  hadc1.Init.SamplingTimeCommon1 = ADC_SAMPLETIME_1CYCLE_5;
  hadc1.Init.SamplingTimeCommon2 = ADC_SAMPLETIME_1CYCLE_5;
  hadc1.Init.OversamplingMode = DISABLE;
  hadc1.Init.TriggerFrequencyMode = ADC_TRIGGER_FREQ_HIGH;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** Configure Regular Channel
  */
//  sConfig.Channel = ADC_CHANNEL_1;
//  sConfig.Rank = ADC_REGULAR_RANK_1;
//  sConfig.SamplingTime = ADC_SAMPLINGTIME_COMMON_1;
//  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
//  {
//    Error_Handler();
//  }
//
//  /** Configure Regular Channel
//  */
//  sConfig.Channel = ADC_CHANNEL_2;
//  sConfig.Rank = ADC_REGULAR_RANK_2;
//  sConfig.SamplingTime = ADC_SAMPLINGTIME_COMMON_2;
//  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
//  {
//    Error_Handler();
//  }
  /* USER CODE BEGIN ADC1_Init 2 */
 
  /* USER CODE END ADC1_Init 2 */
 
}
 
/**
  * @brief DAC1 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_DAC1_Init(void)
{
 
  /* USER CODE BEGIN DAC1_Init 0 */
 
  /* USER CODE END DAC1_Init 0 */
 
  DAC_ChannelConfTypeDef sConfig = {0};
 
  /* USER CODE BEGIN DAC1_Init 1 */
 
  /* USER CODE END DAC1_Init 1 */
 
  /** DAC Initialization
  */
  hdac1.Instance = DAC1;
  if (HAL_DAC_Init(&hdac1) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** DAC channel OUT1 config
  */
  sConfig.DAC_SampleAndHold = DAC_SAMPLEANDHOLD_DISABLE;
  sConfig.DAC_Trigger = DAC_TRIGGER_NONE;
  sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;
  sConfig.DAC_ConnectOnChipPeripheral = DAC_CHIPCONNECT_DISABLE;
  sConfig.DAC_UserTrimming = DAC_TRIMMING_FACTORY;
  if (HAL_DAC_ConfigChannel(&hdac1, &sConfig, DAC_CHANNEL_1) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** DAC channel OUT2 config
  */
  if (HAL_DAC_ConfigChannel(&hdac1, &sConfig, DAC_CHANNEL_2) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN DAC1_Init 2 */
 
  /* USER CODE END DAC1_Init 2 */
 
}
 
/**
  * @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 = 115200;
  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;
  huart3.Init.OverSampling = UART_OVERSAMPLING_16;
  huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart3.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  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 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOD, GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3, GPIO_PIN_RESET);
 
  /*Configure GPIO pin : PA3 */
  GPIO_InitStruct.Pin = GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
 
  /*Configure GPIO pins : PD0 PD1 PD2 PD3 */
  GPIO_InitStruct.Pin = GPIO_PIN_0|GPIO_PIN_1|GPIO_PIN_2|GPIO_PIN_3;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
 
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
 
/* 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 */

 

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Tesla DeLorean
Guru
In response to Tesla DeLorean

‎2023-09-02 6:29 AM

Would suggest polishing your C skills, perhaps easier on a PC than embedded. Currently you'd fail at interview.

#define STRBUFLEN 32

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
  static int index = 0;
  static char string[STRBUFLEN + 1];
  char c;

 /* Prevent unused argument(s) compilation warning */
 UNUSED(huart);

 /* NOTE : This function should not be modified, when the callback is needed,
           the HAL_UART_RxCpltCallback can be implemented in the user file.
  */

  c = rxbuf[0]; // The byte received, first index

  HAL_UART_Receive_IT(&huart3, rxbuf, sizeof(rxbuf)); // restart

  HAL_UART_Transmit(&huart3, &c, sizeof(c), 10); // send the holding buffer, not active input one

  if ((c == '\r') || (c == '\n') || (index >= STRBUFLEN)) // line termination
  {
    string[index] = 0; // NUL terminate string so usable by functions

    if (index) // non-zero, ie has content
    {
      datar7 = atof(string);

      index = 0; // reset pointer in buffer
    }
  }
  else if (index < STRBUFLEN)
  {
    string[index++] = c;
  }
}
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Issamos
Lead II

‎2023-09-02 12:30 AM

Hello @suriya 

You can do this:

float f;

f = (float)rx_data[1];

Hope this is helpful for you. If your question is answered please check this answer as best answer to be diffused.

Best regards.

II

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Tesla DeLorean
Guru

‎2023-09-02 3:58 AM

Use sscanf() or atof() or atod()

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..
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suriya
Associate II
In response to Issamos

‎2023-09-02 5:26 AM

Hi 

I tried this, but it's not working. When I enter "3" in my serial monitor, I get "10.0". In fact, no matter what number I type, I always get "10", and nothing changes.

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suriya
Associate II
In response to Tesla DeLorean

‎2023-09-02 5:29 AM

Hi

i tried atof() still not working.

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Issamos
Lead II
In response to suriya

‎2023-09-02 5:39 AM

Hello again @suriya 

I think you have this problem.

Hope you find a solution here.

Best regards.

II

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suriya
Associate II

‎2023-09-02 5:40 AM

I have attached my code. This code is for testing whether my EEPROM is working or not. I want to receive a value in the UART interrupt, convert it to a float, and then store it in the EEPROM. Float conversion is not working. Please tell me if there is any mistake in my code and also suggest or provide any sample code for this issue.
 
/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "EEPROM.h"
#include"string.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 hi2c2;
 
UART_HandleTypeDef huart3;
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_I2C2_Init(void);
static void MX_USART3_UART_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
#define DEV_ADDR 0xa0
uint8_t dataw1[] = "0.0007896";
uint8_t dataw2[] = "-0.000563";
float dataw3 = 1234.5;
float val = 0.000567;
float val2 = 0.78963;
 
uint8_t datar1[100];
uint8_t datar2[100];
float datar3,datar4,datar5,datar6,datar7;
uint8_t txbuf[64];
uint8_t rxbuf[1];
 
 
 
 
 
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
 /* Prevent unused argument(s) compilation warning */
 UNUSED(huart);
 
 /* NOTE : This function should not be modified, when the callback is needed,
           the HAL_UART_RxCpltCallback can be implemented in the user file.
  */
 HAL_UART_Receive_IT(&huart3, rxbuf, sizeof(rxbuf));
 HAL_UART_Transmit(&huart3, rxbuf,sizeof(rxbuf), 10);
 
 datar6 = (float) rxbuf[1];
 
 datar7 = atof(rxbuf[1]);
 
 
}
 
/* 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_I2C2_Init();
  MX_USART3_UART_Init();
 
  HAL_UART_Receive_IT(&huart3, rxbuf, sizeof(rxbuf));
  /* USER CODE BEGIN 2 */
  for (int i=0; i<512; i++)
    {
    EEPROM_PageErase(i);
    }
 
 
    EEPROM_Write(3, 0, dataw1, strlen((char *)dataw1));
 
    EEPROM_Write(5, 20, dataw2, strlen((char *)dataw2));
 
    EEPROM_Write_NUM (6, 0, dataw3);
 
    EEPROM_Write_NUM (6, 5, val);
 
    EEPROM_Write_NUM (6, 9, val2);
 
 
    EEPROM_Read(3, 0, datar1, 50);
 
    EEPROM_Read(5, 15, datar2, 50);
 
    datar3 = EEPROM_Read_NUM (6, 0);
 
    datar4 = EEPROM_Read_NUM (6, 5);
 
    datar5 = EEPROM_Read_NUM (6, 9);
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
  sprintf((char*)txbuf, "1: %f ", datar6);
  HAL_UART_Transmit(&huart3, txbuf, strlen((char*)txbuf), HAL_MAX_DELAY);
 
  sprintf((char*)txbuf, "2: %f ", datar7);
  HAL_UART_Transmit(&huart3, txbuf, strlen((char*)txbuf), HAL_MAX_DELAY);
 
 
  HAL_Delay(1500);
 
    /* 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_PWREx_ControlVoltageScaling(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.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  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 buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief I2C2 Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_I2C2_Init(void)
{
 
  /* USER CODE BEGIN I2C2_Init 0 */
 
  /* USER CODE END I2C2_Init 0 */
 
  /* USER CODE BEGIN I2C2_Init 1 */
 
  /* USER CODE END I2C2_Init 1 */
  hi2c2.Instance = I2C2;
  hi2c2.Init.Timing = 0x00300F38;
  hi2c2.Init.OwnAddress1 = 0;
  hi2c2.Init.AddressingMode = I2C_ADDRESSINGMODE_7BIT;
  hi2c2.Init.DualAddressMode = I2C_DUALADDRESS_DISABLE;
  hi2c2.Init.OwnAddress2 = 0;
  hi2c2.Init.OwnAddress2Masks = I2C_OA2_NOMASK;
  hi2c2.Init.GeneralCallMode = I2C_GENERALCALL_DISABLE;
  hi2c2.Init.NoStretchMode = I2C_NOSTRETCH_DISABLE;
  if (HAL_I2C_Init(&hi2c2) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** Configure Analogue filter
  */
  if (HAL_I2CEx_ConfigAnalogFilter(&hi2c2, I2C_ANALOGFILTER_ENABLE) != HAL_OK)
  {
    Error_Handler();
  }
 
  /** Configure Digital filter
  */
  if (HAL_I2CEx_ConfigDigitalFilter(&hi2c2, 0) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN I2C2_Init 2 */
 
  /* USER CODE END I2C2_Init 2 */
 
}
 
/**
  * @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 = 115200;
  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;
  huart3.Init.OverSampling = UART_OVERSAMPLING_16;
  huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart3.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  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 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @PAram None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
 
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOB_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
 
/* 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 */

 

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Tesla DeLorean
Guru

‎2023-09-02 6:08 AM

rxbuf[1] is a char, the second in the array, The basis for the index is zero

The functions use strings, ie collections of bytes. You aren't going to hold a floating point string in a single byte.

Strings need to be NUL terminated.

You need to accumulate a string from the bytes as you receive them, and when you've got enough THEN do the conversion on the string.

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Tesla DeLorean
Guru
In response to Tesla DeLorean

‎2023-09-02 6:29 AM

Would suggest polishing your C skills, perhaps easier on a PC than embedded. Currently you'd fail at interview.

#define STRBUFLEN 32

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
  static int index = 0;
  static char string[STRBUFLEN + 1];
  char c;

 /* Prevent unused argument(s) compilation warning */
 UNUSED(huart);

 /* NOTE : This function should not be modified, when the callback is needed,
           the HAL_UART_RxCpltCallback can be implemented in the user file.
  */

  c = rxbuf[0]; // The byte received, first index

  HAL_UART_Receive_IT(&huart3, rxbuf, sizeof(rxbuf)); // restart

  HAL_UART_Transmit(&huart3, &c, sizeof(c), 10); // send the holding buffer, not active input one

  if ((c == '\r') || (c == '\n') || (index >= STRBUFLEN)) // line termination
  {
    string[index] = 0; // NUL terminate string so usable by functions

    if (index) // non-zero, ie has content
    {
      datar7 = atof(string);

      index = 0; // reset pointer in buffer
    }
  }
  else if (index < STRBUFLEN)
  {
    string[index++] = c;
  }
}
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Karl Yamashita
Principal

‎2023-09-02 3:06 PM

What values are you sending to the UART? 

Don't worry, I won't byte.
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