使用STM32F1芯片SPI通信ADS1256差分采集程序

以下是使用STM32F1芯片SPI通信ADS1256差分采集的程序：

#include "stm32f10x.h"
#include "delay.h"
#include "ADS1256.h"

volatile unsigned char ADS1256_DRDY = 0;

void ADS1256_GPIO_Config(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_4;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);
}

void SPI_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_SPI1, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    SPI_InitTypeDef SPI_InitStructure;
    SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
    SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
    SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
    SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
    SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;
    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
    SPI_InitStructure.SPI_CRCPolynomial = 7;
    SPI_Init(SPI1, &SPI_InitStructure);

    SPI_Cmd(SPI1, ENABLE);
}

void ADS1256_DRDY_Interrupt_Config(void)
{
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
    GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource0);

    EXTI_InitStructure.EXTI_Line = EXTI_Line0;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);

    NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x02;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void ADS1256_Init(void)
{
    ADS1256_GPIO_Config();
    ADS1256_DRDY_Interrupt_Config();
    SPI_Configuration();
}

void ADS1256_WaitDRDY(void)
{
    while (!ADS1256_DRDY);
}

void ADS1256_DRDY_Handler(void)
{
    ADS1256_DRDY = 1;
}

unsigned long ADS1256_ReadData(void)
{
    unsigned char data[3];
    unsigned long ret;

    GPIO_ResetBits(GPIOA, GPIO_Pin_1); // CS low

    delay_us(1);

    SPI_I2S_SendData(SPI1, CMD_RDATA);

    while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_BSY) == SET);

    data[0] = SPI_I2S_ReceiveData(SPI1);
    data[1] = SPI_I2S_ReceiveData(SPI1);
    data[2] = SPI_I2S_ReceiveData(SPI1);

    ret = ((unsigned long)data[0] << 16) | ((unsigned long)data[1] << 8) | (unsigned long)data[2];

    GPIO_SetBits(GPIOA, GPIO_Pin_1); // CS high

    return ret;
}

int main(void)
{
    ADS1256_Init();

    while (1)
    {
        ADS1256_WaitDRDY();

        unsigned long data = ADS1256_ReadData();
    }
}

void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET)
    {
        ADS1256_DRDY_Handler();
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

其中，`ADS1256_GPIO_Config()`函数用于初始化ADS1256的GPIO，`SPI_Configuration()`函数用于初始化SPI，`ADS1256_DRDY_Interrupt_Config()`函数用于配置DRDY中断，`ADS1256_Init()`函数用于初始化ADS1256，`ADS1256_WaitDRDY()`函数用于等待DRDY信号的下降沿，`ADS1256_DRDY_Handler()`函数用于处理DRDY中断，`ADS1256_ReadData()`函数用于读取数据。

注意，在使用该程序之前，需要先实现延时函数，例如使用SysTick定时器实现。