STM32读取24位模数转换（24bit ADC）芯片ADS1231数据

ADS1231是一款TI公司出品的24位ADC芯片            ，常用于与称重传感器配合实现体重计的应用
  
  
  
  
  
  
。这里介绍STM32读取ADS1231的电路和代码实现 
  
  
  
  
  
 。ADS1231的特点为通过硬件管脚可控制两种采样速率（10SPS和80SPS）  
 
  
 
  
 
  
 
  
 
  
 
 ，及可以控制芯片上下电以实现低功耗过程控制 


 


 


 


 


 


 。

ADS1231的内部原理如下图所示（固定128倍输入信号放大增益）：

STM32电路连接

ADS1231与STM32的连接关系设计如下图所示：

ADS1231的采样模拟接口可以工作在和数字接口不同的电压












，如模拟供电 AVDD采用 5V
  
  
  
  
  
  ，数字供电采用3.3V,从而与STM32的接口直接连接即可
 
 
 
 
 
 
。

ADS1231测试电路

ADS1231典型的应用连接到惠斯通电桥  
  
  
  
  
  
 ，接收差分电压
 


 


 


 


 


 


，由于内部已固定为128倍信号放大
 
 
 
 
 
 ，所以对于5V供电（AVDD）   
   
   
   
   
   
 ，最大检测差分电压范围为±20mV  
   
   
   
   
   
 。需要注意输入差分信号有共模电压范围要求：

简单测试可以采用如下方式：

当可调电阻器为10欧姆时
 

 

 

 

 

 

，IN+和IN-差分电压为(5/(4700+4700+10))*10 = 5.31mV 

 

 

 

 

 

 。而IN-端电压为2.49734V

 

 

 

 

 

 ，IN+端电压为2.50265V             ，共模和差模电压都在手册电气范围内
 
 

 
 

 
 

 
 

 
 

 
 

，可以微调可调电位器的阻值











，调整输出差模电压

 

 

 

 

 

 
。

ADS1231访问协议

ADS1231可以通过硬件管脚SPEED控制采样速率, 及通过/PWRDONW管脚控制芯片上下电：

读取数据的时序则为： 检测nRDY管脚（也是Dout管脚）状态                   ，如为低电平则可以读取数据 
 
 
 
 
 
 
 
 
 
 
 
，如为高电平则不能读取数据 ； 当数据可读取时


















， 发送24个时钟            ，并在每个时钟的下降沿获得采样数据的24位中的各个位  
 
  
 
  
 
  
 
  
 
  
 
 ，高位优先接收到 24个时钟之后












，多发一个时钟
  
  
  
  
  
  ，使得nRDY管脚回到输出高电平状态  
  
  
  
  
  
 ，在下一次数据可读取时
 


 


 


 


 


 


，ADS1231会将信号拉低

STM32工程配置

这里采用STM32G031F8P6和STM32CUBEIDE开发环境
 
 
 
 
 
 ，实现ADS1231的ADC数据读取            。

首先配置基本工程和时钟系统：

配置UART2作为通讯口 
 

 
 

 
 

 
 

 
 

 
 

 。

配置与ADS1231连接的4个管脚：

保存并生成初始工程代码：

STM32工程代码

代码主要实现微秒级的时序控制   
   
   
   
   
   
 ，采用的微秒延时函数参考： STM32 HAL us delay（微秒延时）的指令延时实现方式及优化

测试逻辑采用以下方式:

串口收到0x01命令
 

 

 

 

 

 

，进行10Hz输出测试 串口收到0x02命令

 

 

 

 

 

 ，进行80Hz输出测试

main.c文件完整代码如下：

/* 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. * ****************************************************************************** */ //Written by Pegasus Yu in 2023 /* USER CODE END Header */ /* Includes ------------------------------------------------------------------*/ #include "main.h" /* Private includes ----------------------------------------------------------*/ /* USER CODE BEGIN Includes */ #include "string.h" /* USER CODE END Includes */ /* Private typedef -----------------------------------------------------------*/ /* USER CODE BEGIN PTD */ /* USER CODE END PTD */ /* Private define ------------------------------------------------------------*/ /* USER CODE BEGIN PD */ __IO float usDelayBase; void PY_usDelayTest(void) { __IO uint32_t firstms, secondms; __IO uint32_t counter = 0; firstms = HAL_GetTick()+1; secondms = firstms+1; while(uwTick!=firstms) ; while(uwTick!=secondms) counter++; usDelayBase = ((float)counter)/1000; } void PY_Delay_us_t(uint32_t Delay) { __IO uint32_t delayReg; __IO uint32_t usNum = (uint32_t)(Delay*usDelayBase); delayReg = 0; while(delayReg!=usNum) delayReg++; } void PY_usDelayOptimize(void) { __IO uint32_t firstms, secondms; __IO float coe = 1.0; firstms = HAL_GetTick(); PY_Delay_us_t(1000000) ; secondms = HAL_GetTick(); coe = ((float)1000)/(secondms-firstms); usDelayBase = coe*usDelayBase; } void PY_Delay_us(uint32_t Delay) { __IO uint32_t delayReg; __IO uint32_t msNum = Delay/1000; __IO uint32_t usNum = (uint32_t)((Delay%1000)*usDelayBase); if(msNum>0) HAL_Delay(msNum); delayReg = 0; while(delayReg!=usNum) delayReg++; } /* USER CODE END PD */ /* Private macro -------------------------------------------------------------*/ /* USER CODE BEGIN PM */ #define ads1231_rdy (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_7)==0)?1:0 #define ads1231_clk_h HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_SET) #define ads1231_clk_l HAL_GPIO_WritePin(GPIOA, GPIO_PIN_6, GPIO_PIN_RESET) #define ads1231_dout HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_7) /* USER CODE END PM */ /* Private variables ---------------------------------------------------------*/ UART_HandleTypeDef huart2; /* USER CODE BEGIN PV */ /* USER CODE END PV */ /* Private function prototypes -----------------------------------------------*/ void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_USART2_UART_Init(void); /* USER CODE BEGIN PFP */ /* USER CODE END PFP */ /* Private user code ---------------------------------------------------------*/ /* USER CODE BEGIN 0 */ uint8_t cmd=0; uint32_t ads1231_data; uint32_t counter=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_USART2_UART_Init(); /* USER CODE BEGIN 2 */ PY_usDelayTest(); PY_usDelayOptimize(); //hardware reset of ADS1231 HAL_GPIO_WritePin(ADS1231_nPDWN_GPIO_Port, ADS1231_nPDWN_Pin, GPIO_PIN_RESET); PY_Delay_us_t(1000000); HAL_GPIO_WritePin(ADS1231_nPDWN_GPIO_Port, ADS1231_nPDWN_Pin, GPIO_PIN_SET); __HAL_UART_CLEAR_FLAG(&huart2, UART_FLAG_RXNE); HAL_UART_Receive_IT(&huart2, (uint8_t *)&cmd, 1); /* USER CODE END 2 */ /* Infinite loop */ /* USER CODE BEGIN WHILE */ while (1) { if(cmd==0x01) //10SPS { HAL_GPIO_WritePin(ADS1231_SPEED_GPIO_Port, ADS1231_SPEED_Pin, GPIO_PIN_RESET); while(ads1231_rdy) PY_Delay_us_t(1); while(!ads1231_rdy) PY_Delay_us_t(1); ads1231_data = 0; PY_Delay_us_t(1); for(uint8_t i=1;i<=24;i++) { ads1231_clk_h; PY_Delay_us_t(1); ads1231_clk_l; ads1231_data |= (ads1231_dout<<(24-i)); PY_Delay_us_t(1); } ads1231_clk_h; PY_Delay_us_t(1); ads1231_clk_l; PY_Delay_us_t(1); HAL_UART_Transmit(&huart2, &ads1231_data, 3, 2700); counter++; if(counter%10==0) PY_Delay_us_t(1000000); } if(cmd==0x02) //80SPS { HAL_GPIO_WritePin(ADS1231_SPEED_GPIO_Port, ADS1231_SPEED_Pin, GPIO_PIN_SET); while(ads1231_rdy) PY_Delay_us_t(1); while(!ads1231_rdy) PY_Delay_us_t(1); ads1231_data = 0; PY_Delay_us_t(1); for(uint8_t i=1;i<=24;i++) { ads1231_clk_h; PY_Delay_us_t(1); ads1231_clk_l; ads1231_data |= (ads1231_dout<<(24-i)); PY_Delay_us_t(1); } ads1231_clk_h; PY_Delay_us_t(1); ads1231_clk_l; PY_Delay_us_t(1); HAL_UART_Transmit(&huart2, &ads1231_data, 3, 2700); counter++; if(counter%80==0) PY_Delay_us_t(1000000); } /* 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_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_DIV1; if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK) { Error_Handler(); } } /** * @brief USART2 Initialization Function * @param None * @retval None */ static void MX_USART2_UART_Init(void) { /* USER CODE BEGIN USART2_Init 0 */ /* USER CODE END USART2_Init 0 */ /* USER CODE BEGIN USART2_Init 1 */ /* USER CODE END USART2_Init 1 */ huart2.Instance = USART2; huart2.Init.BaudRate = 115200; huart2.Init.WordLength = UART_WORDLENGTH_8B; huart2.Init.StopBits = UART_STOPBITS_1; huart2.Init.Parity = UART_PARITY_NONE; huart2.Init.Mode = UART_MODE_TX_RX; huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE; huart2.Init.OverSampling = UART_OVERSAMPLING_16; huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE; huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1; huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT; if (HAL_UART_Init(&huart2) != HAL_OK) { Error_Handler(); } /* USER CODE BEGIN USART2_Init 2 */ /* USER CODE END USART2_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(); /*Configure GPIO pin Output Level */ HAL_GPIO_WritePin(GPIOA, ADS1231_SPEED_Pin|ADS1231_SCK_Pin, GPIO_PIN_RESET); /*Configure GPIO pin Output Level */ HAL_GPIO_WritePin(ADS1231_nPDWN_GPIO_Port, ADS1231_nPDWN_Pin, GPIO_PIN_SET); /*Configure GPIO pins : ADS1231_SPEED_Pin ADS1231_nPDWN_Pin */ GPIO_InitStruct.Pin = ADS1231_SPEED_Pin|ADS1231_nPDWN_Pin; GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP; GPIO_InitStruct.Pull = GPIO_NOPULL; GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW; HAL_GPIO_Init(GPIOA, &GPIO_InitStruct); /*Configure GPIO pin : ADS1231_SCK_Pin */ GPIO_InitStruct.Pin = ADS1231_SCK_Pin; GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP; GPIO_InitStruct.Pull = GPIO_NOPULL; GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH; HAL_GPIO_Init(ADS1231_SCK_GPIO_Port, &GPIO_InitStruct); /*Configure GPIO pin : ADS1231_nDRDY_DOUT_Pin */ GPIO_InitStruct.Pin = ADS1231_nDRDY_DOUT_Pin; GPIO_InitStruct.Mode = GPIO_MODE_INPUT; GPIO_InitStruct.Pull = GPIO_PULLUP; HAL_GPIO_Init(ADS1231_nDRDY_DOUT_GPIO_Port, &GPIO_InitStruct); /* USER CODE BEGIN MX_GPIO_Init_2 */ /* USER CODE END MX_GPIO_Init_2 */ } /* USER CODE BEGIN 4 */ void HAL_UART_RxCpltCallback(UART_HandleTypeDef *UartHandle) { HAL_UART_Receive_IT(&huart2, (uint8_t *)&cmd, 1); } /* 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 */

代码实现十六进制数据输出             ，如果要切换为串口printf打印输出
 
 

 
 

 
 

 
 

 
 

 
 

，可以参考：

STM32 UART串口printf函数应用及浮点打印代码空间节省 (HAL)

输出的24位数据为补码格式











，进行绝对值提取时按照如下规则：

测试效果

串口命令0x01输出（间隔1秒输入10个采样值）：

串口命令0x02输出（间隔1秒输出80个采样值）：

例程下载

STM32G031F8P6-ADS1231例程

–End–