472 lines
15 KiB
C
472 lines
15 KiB
C
/**
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* ads1256_linux.c
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*
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* Linux C 通过 SPI 采集 ADS1256 示例
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* 适用平台: Raspberry Pi / 任何 Linux + SPI 设备
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* 编译: gcc -o ads1256 ads1256_linux.c -lwiringPi (树莓派用 wiringPi)
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* gcc -o ads1256 ads1256_linux.c (通用 /dev/spidev)
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*
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* ADS1256: TI 24位 8通道 ΔΣ ADC, 最高 30kSPS
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*/
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#include <stdio.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <sys/ioctl.h>
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#include <linux/spi/spidev.h>
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#include <time.h>
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// ============================================================
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// 配置参数 - 按需修改
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// ============================================================
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#define SPI_DEVICE "/dev/spidev0.0" // SPI 设备路径
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#define SPI_SPEED 1920000 // SPI 时钟 (1.92MHz, ADS1256 最大支持 2MHz)
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#define SPI_MODE 1 // SPI 模式: CPOL=0, CPHA=1 (模式1)
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#define SPI_BITS 8 // 8 位传输
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// ADS1256 片选用 GPIO (如果使用硬件 CS 则不需要)
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// 若用 /dev/spidev 的硬件 CS, 这部分不需要手动控制
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// #define CS_PIN 8 // 例如 wiringPi 的 GPIO 8
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// ============================================================
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// ADS1256 寄存器地址
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// ============================================================
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#define ADS1256_REG_STATUS 0x00
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#define ADS1256_REG_MUX 0x01
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#define ADS1256_REG_ADCON 0x02
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#define ADS1256_REG_DRATE 0x03
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#define ADS1256_REG_IO 0x04
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#define ADS1256_REG_OFC0 0x05
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#define ADS1256_REG_OFC1 0x06
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#define ADS1256_REG_OFC2 0x07
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#define ADS1256_REG_FSC0 0x08
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#define ADS1256_REG_FSC1 0x09
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#define ADS1256_REG_FSC2 0x0A
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// ============================================================
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// ADS1256 命令定义
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// ============================================================
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#define ADS1256_CMD_WAKEUP 0x00 // 退出待机
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#define ADS1256_CMD_RDATA 0x01 // 读数据
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#define ADS1256_CMD_RDATAC 0x03 // 连续读数据
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#define ADS1256_CMD_SDATAC 0x0F // 停止连续读
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#define ADS1256_CMD_RREG 0x10 // 读寄存器 (| 寄存器地址)
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#define ADS1256_CMD_WREG 0x50 // 写寄存器 (| 寄存器地址)
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#define ADS1256_CMD_SELFCAL 0xF0 // 自校准
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#define ADS1256_CMD_SELFOCAL 0xF1 // 自失调校准
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#define ADS1256_CMD_SELFGCAL 0xF2 // 自增益校准
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#define ADS1256_CMD_SYSOCAL 0xF3 // 系统失调校准
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#define ADS1256_CMD_SYSGCAL 0xF4 // 系统增益校准
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#define ADS1256_CMD_SYNC 0xFC // 同步
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#define ADS1256_CMD_STANDBY 0xFD // 待机
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#define ADS1256_CMD_RESET 0xFE // 复位
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// ============================================================
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// ADS1256 数据速率 (DRATE 寄存器值)
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// ============================================================
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#define ADS1256_DRATE_30000 0xF0 // 30,000 SPS
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#define ADS1256_DRATE_15000 0xE0 // 15,000 SPS
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#define ADS1256_DRATE_7500 0xD0 // 7,500 SPS
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#define ADS1256_DRATE_3750 0xC0 // 3,750 SPS
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#define ADS1256_DRATE_2000 0xB0 // 2,000 SPS
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#define ADS1256_DRATE_1000 0xA0 // 1,000 SPS
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#define ADS1256_DRATE_500 0x90 // 500 SPS
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#define ADS1256_DRATE_100 0x80 // 100 SPS
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#define ADS1256_DRATE_60 0x70 // 60 SPS
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#define ADS1256_DRATE_50 0x60 // 50 SPS
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#define ADS1256_DRATE_30 0x50 // 30 SPS
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#define ADS1256_DRATE_25 0x40 // 25 SPS
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#define ADS1256_DRATE_15 0x30 // 15 SPS
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#define ADS1256_DRATE_10 0x20 // 10 SPS
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#define ADS1256_DRATE_5 0x10 // 5 SPS
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// ============================================================
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// PGA 增益 (ADCON 寄存器的低 3 位)
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// ============================================================
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#define ADS1256_PGA_1 0x00 // ±5V
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#define ADS1256_PGA_2 0x01 // ±2.5V
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#define ADS1256_PGA_4 0x02 // ±1.25V
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#define ADS1256_PGA_8 0x03 // ±0.625V
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#define ADS1256_PGA_16 0x04 // ±0.3125V
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#define ADS1256_PGA_32 0x05 // ±0.15625V
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#define ADS1256_PGA_64 0x06 // ±0.078125V
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// 参考电压 (V)
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#define ADS1256_VREF 2.5
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// ============================================================
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// 全局变量
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// ============================================================
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static int spi_fd = -1; // SPI 文件描述符
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static uint8_t spi_txbuf[32];
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static uint8_t spi_rxbuf[32];
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// ============================================================
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// SPI 初始化
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// ============================================================
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int spi_init(const char *device, uint32_t speed, uint8_t mode, uint8_t bits)
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{
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int ret;
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spi_fd = open(device, O_RDWR);
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if (spi_fd < 0) {
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perror("打开 SPI 设备失败");
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return -1;
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}
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// 设置 SPI 模式
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ret = ioctl(spi_fd, SPI_IOC_WR_MODE, &mode);
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if (ret < 0) {
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perror("设置 SPI 模式失败");
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close(spi_fd);
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return -1;
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}
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// 设置位数
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ret = ioctl(spi_fd, SPI_IOC_WR_BITS_PER_WORD, &bits);
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if (ret < 0) {
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perror("设置 SPI 位数失败");
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close(spi_fd);
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return -1;
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}
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// 设置速度
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ret = ioctl(spi_fd, SPI_IOC_WR_MAX_SPEED_HZ, &speed);
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if (ret < 0) {
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perror("设置 SPI 速度失败");
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close(spi_fd);
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return -1;
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}
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// 读取并验证设置
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uint8_t rb_mode, rb_bits;
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uint32_t rb_speed;
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ioctl(spi_fd, SPI_IOC_RD_MODE, &rb_mode);
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ioctl(spi_fd, SPI_IOC_RD_BITS_PER_WORD, &rb_bits);
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ioctl(spi_fd, SPI_IOC_RD_MAX_SPEED_HZ, &rb_speed);
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printf("SPI 初始化完成: 模式=%d, 位数=%d, 速度=%d Hz\n",
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rb_mode, rb_bits, rb_speed);
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return 0;
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}
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// ============================================================
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// SPI 收发 (全双工)
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// ============================================================
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int spi_transfer(uint8_t *tx, uint8_t *rx, int len)
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{
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struct spi_ioc_transfer tr = {
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.tx_buf = (unsigned long)tx,
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.rx_buf = (unsigned long)rx,
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.len = (uint32_t)len,
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.delay_usecs = 0,
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.speed_hz = SPI_SPEED,
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.bits_per_word = SPI_BITS,
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.cs_change = 0,
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};
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int ret = ioctl(spi_fd, SPI_IOC_MESSAGE(1), &tr);
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if (ret < 0) {
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perror("SPI 传输失败");
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}
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return ret;
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}
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// ============================================================
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// SPI 发送单字节
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// ============================================================
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static inline void spi_write_byte(uint8_t byte)
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{
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spi_txbuf[0] = byte;
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spi_transfer(spi_txbuf, spi_rxbuf, 1);
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}
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// ============================================================
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// SPI 读单字节
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// ============================================================
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static inline uint8_t spi_read_byte(void)
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{
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spi_txbuf[0] = 0xFF; // MOSI 发 0xFF 以产生时钟
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spi_transfer(spi_txbuf, spi_rxbuf, 1);
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return spi_rxbuf[0];
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}
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// ============================================================
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// 等待 DRDY 引脚变低 (数据就绪)
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//
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// 注意: 这里用延时模拟等待，实际应接 GPIO 中断或轮询
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// 若 DRDY 接了 GPIO (如 wiringPi 的 pin 25)，可改为:
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// while(digitalRead(DRDY_PIN));
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// ============================================================
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void wait_drdy(void)
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{
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// 实际项目中用 GPIO 轮询更准确
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// 这里用延时估算
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usleep(100); // 100us，根据采样率调整
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}
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// ============================================================
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// ADS1256 复位
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// ============================================================
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void ads1256_reset(void)
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{
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spi_write_byte(ADS1256_CMD_RESET);
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usleep(1000); // 等待复位完成
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spi_write_byte(ADS1256_CMD_WAKEUP); // 退出待机
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usleep(1000);
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}
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// ============================================================
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// 写 ADS1256 寄存器
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// ============================================================
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void ads1256_write_reg(uint8_t reg, uint8_t value)
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{
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spi_write_byte(ADS1256_CMD_WREG | reg);
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spi_write_byte(0x00); // 后续字节数 - 1 (0 = 1 byte)
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spi_write_byte(value);
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}
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// ============================================================
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// 读 ADS1256 寄存器
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// ============================================================
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uint8_t ads1256_read_reg(uint8_t reg)
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{
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spi_write_byte(ADS1256_CMD_RREG | reg);
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spi_write_byte(0x00); // 后续字节数 - 1
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return spi_read_byte();
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}
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// ============================================================
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// 设置输入通道 (MUX 寄存器)
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//
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// mux:
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// 单端模式: POS = channel, NEG = 0x08 (AINCOM)
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// 差分模式: POS = channel_p, NEG = channel_n
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// ============================================================
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void ads1256_set_channel(uint8_t pos, uint8_t neg)
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{
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uint8_t mux = ((pos & 0x07) << 4) | (neg & 0x07);
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ads1256_write_reg(ADS1256_REG_MUX, mux);
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usleep(1);
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}
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// ============================================================
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// ADS1256 初始化
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// ============================================================
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int ads1256_init(void)
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{
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printf("正在初始化 ADS1256...\n");
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// 1. 复位 ADS1256
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ads1256_reset();
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usleep(10000);
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// 2. 配置状态寄存器
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// BIT7: ID (只读)
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// BIT6: ID (只读)
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// BIT5: ORDER = 0 (MSB 优先)
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// BIT4: ACAL = 1 (自动校准)
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// BIT3: BUFEN = 0 (关闭缓冲)
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// BIT2: DRB = 0 (DRDY 低有效)
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// BIT1-0: 保留
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ads1256_write_reg(ADS1256_REG_STATUS, 0x14); // 0b00010100
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// 3. 配置 MUX (默认: AIN0 + AINCOM)
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ads1256_set_channel(0, 0x08);
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// 4. 配置 ADCON (A/D 控制寄存器)
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// BIT7-5: CLK1-0 = 00 (时钟输出关), SDCS = 0
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// BIT4-3: 保留
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// BIT2-0: PGA = 001 (增益 ×2)
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ads1256_write_reg(ADS1256_REG_ADCON, ADS1256_PGA_2);
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// 5. 设置数据速率 (1000 SPS)
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ads1256_write_reg(ADS1256_REG_DRATE, ADS1256_DRATE_1000);
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// 6. 自校准
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printf("正在进行自校准...\n");
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spi_write_byte(ADS1256_CMD_SELFCAL);
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// 等待校准完成 (约 400ms @ 1000SPS)
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usleep(500000);
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printf("ADS1256 初始化完成!\n");
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// 读寄存器验证
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uint8_t status = ads1256_read_reg(ADS1256_REG_STATUS);
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uint8_t mux = ads1256_read_reg(ADS1256_REG_MUX);
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uint8_t adcon = ads1256_read_reg(ADS1256_REG_ADCON);
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uint8_t drate = ads1256_read_reg(ADS1256_REG_DRATE);
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printf("寄存器状态: STATUS=0x%02X, MUX=0x%02X, ADCON=0x%02X, DRATE=0x%02X\n",
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status, mux, adcon, drate);
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return 0;
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}
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// ============================================================
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// 单次读取 24 位数据
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//
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// 返回: 24 位有符号整数 (二进制补码)
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// ============================================================
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int32_t ads1256_read_data(void)
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{
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uint8_t buf[3];
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// 发送 RDATA 命令
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wait_drdy();
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spi_write_byte(ADS1256_CMD_RDATA);
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// 读 3 字节 (24 位)
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buf[0] = spi_read_byte();
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buf[1] = spi_read_byte();
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buf[2] = spi_read_byte();
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// 组合成 32 位有符号数 (符号扩展)
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int32_t value;
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value = ((int32_t)buf[0] << 16) |
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((int32_t)buf[1] << 8) |
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((int32_t)buf[2]);
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// 24 位有符号数符号扩展
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if (value & 0x800000) {
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value |= 0xFF000000;
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}
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return value;
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}
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// ============================================================
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// 将原始值转换为电压
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// ============================================================
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double ads1256_raw_to_voltage(int32_t raw, uint8_t pga)
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{
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// ADS1256 满量程 = ±VREF / PGA
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// 24 位: -2^23 ~ 2^23-1
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double voltage = (double)raw * ADS1256_VREF / (double)(1 << 23) / (double)pga;
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return voltage;
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}
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// ============================================================
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// 读取指定单端通道
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// ============================================================
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int32_t ads1256_read_channel(uint8_t ch)
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{
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ads1256_set_channel(ch, 0x08); // AINch vs AINCOM
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usleep(1);
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// 发送 SYNC + WAKEUP 以启动转换
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spi_write_byte(ADS1256_CMD_SYNC);
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usleep(1);
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spi_write_byte(ADS1256_CMD_WAKEUP);
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// 等待转换完成 (根据采样率调整)
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// 1000 SPS -> 约 1ms
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usleep(2000);
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return ads1256_read_data();
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}
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// ============================================================
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// 读取指定差分通道
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// ============================================================
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int32_t ads1256_read_diff(uint8_t pos, uint8_t neg)
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{
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ads1256_set_channel(pos, neg);
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usleep(1);
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spi_write_byte(ADS1256_CMD_SYNC);
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usleep(1);
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spi_write_byte(ADS1256_CMD_WAKEUP);
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usleep(2000);
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return ads1256_read_data();
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}
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// ============================================================
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// 连续扫描所有 8 个单端通道
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// ============================================================
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void ads1256_scan_all(void)
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{
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printf("\n===== 多通道扫描 =====\n");
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for (int ch = 0; ch < 8; ch++) {
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int32_t raw = ads1256_read_channel(ch);
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double volts = ads1256_raw_to_voltage(raw, 2); // PGA=2
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printf("通道 AIN%d: raw = %7d, 电压 = %+.6f V\n", ch, raw, volts);
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}
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}
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// ============================================================
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// SPI 关闭
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// ============================================================
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void spi_close(void)
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{
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if (spi_fd >= 0) {
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close(spi_fd);
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spi_fd = -1;
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}
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}
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// ============================================================
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// 毫秒延时
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// ============================================================
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void delay_ms(int ms)
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{
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struct timespec ts;
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ts.tv_sec = ms / 1000;
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ts.tv_nsec = (ms % 1000) * 1000000L;
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nanosleep(&ts, NULL);
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}
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// ============================================================
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// 主函数
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// ============================================================
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int main(int argc, char *argv[])
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{
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printf("ADS1256 Linux SPI 采集示例\n");
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printf("===========================\n\n");
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// 1. 初始化 SPI
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if (spi_init(SPI_DEVICE, SPI_SPEED, SPI_MODE, SPI_BITS) < 0) {
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return 1;
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}
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// 2. 初始化 ADS1256
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if (ads1256_init() < 0) {
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spi_close();
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return 1;
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}
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printf("\n===== 单通道测试 (AIN0) =====\n");
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for (int i = 0; i < 10; i++) {
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int32_t raw = ads1256_read_channel(0);
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double volts = ads1256_raw_to_voltage(raw, 2);
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printf("[%d] raw=%7d, voltage=%+.6f V\n", i, raw, volts);
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delay_ms(10);
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}
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// 3. 扫描所有通道
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ads1256_scan_all();
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||
// 4. 差分模式示例 (AIN0 - AIN1)
|
||
printf("\n===== 差分测试 (AIN0 - AIN1) =====\n");
|
||
for (int i = 0; i < 5; i++) {
|
||
int32_t raw = ads1256_read_diff(0, 1);
|
||
double volts = ads1256_raw_to_voltage(raw, 2);
|
||
printf("[%d] raw=%7d, voltage=%+.6f V\n", i, raw, volts);
|
||
delay_ms(10);
|
||
}
|
||
|
||
// 5. 清理
|
||
spi_close();
|
||
printf("\n程序结束.\n");
|
||
|
||
return 0;
|
||
}
|