STM32 MCO+SPI獲取24位模數(shù)轉(zhuǎn)換（24bit ADC）高速芯片ADS1271采樣數(shù)據(jù)
STM32大部分芯片只有12位的ADC采樣性能，如果要實(shí)現(xiàn)更高精度的模數(shù)轉(zhuǎn)換如24位ADC采樣，則需要連接外部ADC實(shí)現(xiàn)。ADS1271是 TI公司一款高速24位Σ-Δ型模數(shù)轉(zhuǎn)換器(ADC) ,數(shù)據(jù)率達(dá)到105K SPS, 即一秒可以采樣105000次。
這里介紹基于A(yíng)DS1271的24位ADC采樣實(shí)現(xiàn)。采用STM32CUBEIDE開(kāi)發(fā)工具，以STM32F401CCU6為例。
ADS1271操作方式
ADS1271的管腳定義如下所示：
ADS1271采用雙電壓模式，即模擬電壓和數(shù)字電壓可以單獨(dú)設(shè)置，因此典型應(yīng)用為模擬電壓接5V，數(shù)字電壓接3.3V，從而數(shù)字邏輯管腳可以與STM32直接連接。
ADS1271有三種模式： 高速，高分辨率和低功耗，這里只介紹高速模式的例程，其它的模式可以相應(yīng)調(diào)整即可。因此MODE管腳拉低。
ADS1271有三種數(shù)據(jù)輸出方式： SPI, MO, FS, 這里只介紹SPI模式，其它的模式可以相應(yīng)調(diào)整即可。因此FORMAT管腳拉低。
/SYNC_/PDWN用作上下電控制，因此保持上電狀態(tài)，一直拉高。
DIN管腳可以用作級(jí)聯(lián)采樣方式，這里只介紹單片采樣方式，因此DIN管腳必須拉低。
DOUT為數(shù)據(jù)輸出管腳，STM32輸出上升沿給ADS1271時(shí)ADS1271送出數(shù)據(jù)，STM32輸出下降沿時(shí)自身采樣數(shù)據(jù)。
/DRDY_FSYNC用作ADS1271數(shù)據(jù)準(zhǔn)備好的報(bào)告，對(duì)STM32為輸入管腳連接。
SCLK為數(shù)據(jù)獲取時(shí)鐘，SCLK需要保證在兩次/DRDY_FSYNC之間能夠讀取完一次ADS1271準(zhǔn)備好的數(shù)據(jù)。
CLK為需要提供給ADS1271的高速時(shí)鐘，最小值為100KHz，最大值為27MHz。這里通過(guò)STM32的MCO(Master Clock Out)專(zhuān)用功能管腳連接提供此時(shí)鐘。
VREFP連接到一個(gè)2.5V左右的穩(wěn)壓源，因?yàn)楣苣_內(nèi)部有４.２Ｋ阻值特性，因此可以在外部通過(guò)連接一個(gè)４.７Ｋ電阻到５Ｖ，為了提高參考電壓穩(wěn)定性，需要給５Ｖ電壓放置一個(gè)大的濾波電容。
AINP/AINN則連接要采樣的差分電壓。
本例程的連接關(guān)系為：
STM32工程配置
首先創(chuàng)建基本工程并設(shè)置時(shí)鐘：
配置MCO輸出時(shí)鐘頻率為21MHz：
設(shè)置PA4為GPIO輸入管腳作為/DRDY_FSYNC， 設(shè)置SPI1作為數(shù)據(jù)獲取接口：
只連接SPI1的PA5和PA6，作為時(shí)鐘和數(shù)據(jù)獲取管腳：
本例程不采用中斷和DMA方式，直接配置接口參數(shù)：
配置USB虛擬串口作為數(shù)據(jù)輸出端口：
保存并生成初始工程代碼;
STM32工程代碼
例程代碼實(shí)現(xiàn)連續(xù)獲取5000次采樣數(shù)據(jù)后，做一次平均，再輸出24位采樣平均值。
完整的例程代碼main.c：
/* 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 "usb_device.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 */
__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 */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
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);
/* USER CODE BEGIN PFP */
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
#define ADS1271_DRDY HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_4)
uint32_t ads1271_data;
void ADS1271_Get_Data(void)
{
while(ADS1271_DRDY!=0) PY_Delay_us_t(1);
HAL_SPI_Receive(&hspi1, (uint8_t *)&ads1271_data, 3, 2700);
while(ADS1271_DRDY==0) PY_Delay_us_t(1);
}
#define avg_times 5000
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
uint32_t i;
uint32_t Buff[avg_times];
uint64_t sum = 0;
uint32_t avg = 0;
/* 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_USB_DEVICE_Init();
MX_SPI1_Init();
/* USER CODE BEGIN 2 */
PY_usDelayTest();
PY_usDelayOptimize();
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
for(i=0; i<avg_times; i++)
{
ADS1271_Get_Data();
Buff[i] = ads1271_data;
}
sum = 0;
for(i=0; i<avg_times; i++)
{
sum += (Buff[i]>>16)|(Buff[i]&0x0000ff00)|((Buff[i]&0x000000ff)<<16);
}
avg = sum/avg_times;
while(CDC_Transmit_FS((uint8_t*)&avg, 3)==USBD_BUSY) PY_Delay_us_t(1);
/* 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_SCALE2);
/** 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 = 25;
RCC_OscInitStruct.PLL.PLLN = 336;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
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_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
{
Error_Handler();
}
HAL_RCC_MCOConfig(RCC_MCO1, RCC_MCO1SOURCE_PLLCLK, RCC_MCODIV_4);
}
/**
* @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_HIGH;
hspi1.Init.CLKPhase = SPI_PHASE_1EDGE;
hspi1.Init.NSS = SPI_NSS_SOFT;
hspi1.Init.BaudRatePrescaler = SPI_BAUDRATEPRESCALER_8;
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_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */
/* GPIO Ports Clock Enable */
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/*Configure GPIO pin : PA4 */
GPIO_InitStruct.Pin = GPIO_PIN_4;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_PULLUP;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/*Configure GPIO pin : PA8 */
GPIO_InitStruct.Pin = GPIO_PIN_8;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF0_MCO;
HAL_GPIO_Init(GPIOA, &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 */
STM32測(cè)試輸出
串口測(cè)試輸出如下：
STM32例程下載
STM32 MCO+SPI獲取24位模數(shù)轉(zhuǎn)換（24bit ADC）高速芯片ADS1271采樣數(shù)據(jù)例程文章來(lái)源：http://www.zghlxwxcb.cn/news/detail-573865.html
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