587 lines
19 KiB
C
587 lines
19 KiB
C
/**
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* ads1115_linux.c
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*
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* Linux C 通过 I2C 采集 ADS1115 示例
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* ADS1115: TI 16位 4通道 ΔΣ ADC, 最高 860SPS, I2C 接口
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*
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* 编译: gcc -o ads1115 ads1115_linux.c
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* 运行: ./ads1115
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* ./ads1115 0x48 # 指定 I2C 地址
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* ./ads1115 0x48 1 2 # 指定地址、PGA、数据速率
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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/i2c-dev.h>
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#include <time.h>
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#include <math.h>
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// ============================================================
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// I2C 配置
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// ============================================================
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#define I2C_DEVICE "/dev/i2c-1" // I2C 总线 (树莓派是 i2c-1)
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#define ADS1115_ADDR 0x48 // ADDR 接 GND 时默认地址
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// ============================================================
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// ADS1115 寄存器
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// ============================================================
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#define ADS1115_REG_CONVERSION 0x00 // 转换结果 (只读)
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#define ADS1115_REG_CONFIG 0x01 // 配置寄存器 (读/写)
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#define ADS1115_REG_LO_THRESH 0x02 // 低阈值比较
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#define ADS1115_REG_HI_THRESH 0x03 // 高阈值比较
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// ============================================================
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// ADS1115 配置寄存器 bit 定义 (16 位)
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// ============================================================
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// BIT15: OS[0] — 单次转换启动位 (1=开始)
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// BIT14-12: MUX[2:0] — 输入多路选择
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// BIT11-9: PGA[2:0] — 可编程增益放大器
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// BIT8: MODE — 0=连续转换, 1=单次(省电)
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// BIT7-5: DR[2:0] — 数据速率
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// BIT4: COMP_MODE — 比较模式 (0=传统)
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// BIT3: COMP_POL — 比较极性 (0=低有效)
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// BIT2: COMP_LAT — 比较锁存 (0=不锁存)
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// BIT1-0: COMP_QUE — 比较器队列 (11=禁用)
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// --- MUX 输入通道 ---
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#define ADS1115_MUX_AIN0_AIN1 0x0000 // 差分: P=AIN0, N=AIN1 (默认)
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#define ADS1115_MUX_AIN0_AIN3 0x1000 // 差分: P=AIN0, N=AIN3
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#define ADS1115_MUX_AIN1_AIN3 0x2000 // 差分: P=AIN1, N=AIN3
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#define ADS1115_MUX_AIN2_AIN3 0x3000 // 差分: P=AIN2, N=AIN3
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#define ADS1115_MUX_AIN0_GND 0x4000 // 单端: AIN0
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#define ADS1115_MUX_AIN1_GND 0x5000 // 单端: AIN1
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#define ADS1115_MUX_AIN2_GND 0x6000 // 单端: AIN2
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#define ADS1115_MUX_AIN3_GND 0x7000 // 单端: AIN3
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// --- PGA 增益 (满量程范围) ---
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#define ADS1115_PGA_6_144V 0x0000 // ±6.144V (1LSB=0.1875mV)
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#define ADS1115_PGA_4_096V 0x0200 // ±4.096V (1LSB=0.125mV)
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#define ADS1115_PGA_2_048V 0x0400 // ±2.048V (1LSB=0.0625mV) (默认)
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#define ADS1115_PGA_1_024V 0x0600 // ±1.024V (1LSB=0.03125mV)
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#define ADS1115_PGA_0_512V 0x0800 // ±0.512V (1LSB=0.015625mV)
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#define ADS1115_PGA_0_256V 0x0A00 // ±0.256V (1LSB=0.0078125mV)
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// --- 数据速率 ---
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#define ADS1115_DR_8SPS 0x0000 // 8 SPS
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#define ADS1115_DR_16SPS 0x0020 // 16 SPS
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#define ADS1115_DR_32SPS 0x0040 // 32 SPS
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#define ADS1115_DR_64SPS 0x0060 // 64 SPS
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#define ADS1115_DR_128SPS 0x0080 // 128 SPS (默认)
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#define ADS1115_DR_250SPS 0x00A0 // 250 SPS
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#define ADS1115_DR_475SPS 0x00C0 // 475 SPS
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#define ADS1115_DR_860SPS 0x00E0 // 860 SPS
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// --- 比较器队列 (COMP_QUE) ---
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#define ADS1115_COMP_QUE_1 0x0000 // 1 次后触发
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#define ADS1115_COMP_QUE_2 0x0001 // 2 次后触发
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#define ADS1115_COMP_QUE_4 0x0002 // 4 次后触发
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#define ADS1115_COMP_QUE_DISABLE 0x0003 // 禁用比较器 (默认)
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// --- 操作模式 ---
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#define ADS1115_MODE_CONTINUOUS 0x0000 // 连续转换
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#define ADS1115_MODE_SINGLE 0x0100 // 单次转换 (默认, 省电)
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// --- 启动转换 ---
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#define ADS1115_OS_START 0x8000 // 启动单次转换
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// ============================================================
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// 结构体: ADS1115 配置上下文
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// ============================================================
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typedef struct {
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int fd; // I2C 文件描述符
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uint8_t addr; // I2C 设备地址
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uint16_t config; // 当前配置值
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double fs_voltage; // 满量程电压 (取决于 PGA)
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} ads1115_t;
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// ============================================================
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// PGA 对应的满量程电压 (单位: V)
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// ============================================================
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static const double pga_fs[] = {
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[0] = 6.144, // ADS1115_PGA_6_144V
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[1] = 4.096, // ADS1115_PGA_4_096V
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[2] = 2.048, // ADS1115_PGA_2_048V
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[3] = 1.024, // ADS1115_PGA_1_024V
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[4] = 0.512, // ADS1115_PGA_0_512V
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[5] = 0.256, // ADS1115_PGA_0_256V
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};
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// ============================================================
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// PGA 增益对应的满量程电压名
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// ============================================================
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static const char *pga_names[] = {
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[0] = "±6.144V",
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[1] = "±4.096V",
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[2] = "±2.048V",
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[3] = "±1.024V",
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[4] = "±0.512V",
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[5] = "±0.256V",
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};
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// ============================================================
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// 数据速率字符串
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// ============================================================
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static const char *dr_names[] = {
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[0] = "8 SPS",
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[1] = "16 SPS",
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[2] = "32 SPS",
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[3] = "64 SPS",
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[4] = "128 SPS",
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[5] = "250 SPS",
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[6] = "475 SPS",
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[7] = "860 SPS",
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};
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// ============================================================
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// 毫秒延时
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// ============================================================
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static 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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// 微秒延时
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// ============================================================
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static void delay_us(int us)
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{
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struct timespec ts;
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ts.tv_sec = us / 1000000;
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ts.tv_nsec = (us % 1000000) * 1000L;
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nanosleep(&ts, NULL);
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}
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// ============================================================
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// I2C 初始化
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// ============================================================
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static int i2c_init(ads1115_t *dev, const char *i2c_dev, uint8_t addr)
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{
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dev->fd = open(i2c_dev, O_RDWR);
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if (dev->fd < 0) {
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perror("打开 I2C 设备失败");
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return -1;
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}
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if (ioctl(dev->fd, I2C_SLAVE, addr) < 0) {
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perror("设置 I2C 从机地址失败");
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close(dev->fd);
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dev->fd = -1;
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return -1;
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}
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dev->addr = addr;
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dev->config = 0;
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printf("I2C 初始化完成: 设备=%s, 地址=0x%02X\n", i2c_dev, addr);
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return 0;
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}
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// ============================================================
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// I2C 写 2 字节 (大端)
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// ============================================================
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static int i2c_write_word(ads1115_t *dev, uint8_t reg, uint16_t value)
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{
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uint8_t buf[3];
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buf[0] = reg;
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buf[1] = (value >> 8) & 0xFF; // 高字节
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buf[2] = value & 0xFF; // 低字节
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if (write(dev->fd, buf, 3) != 3) {
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perror("I2C 写失败");
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return -1;
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}
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return 0;
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}
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// ============================================================
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// I2C 读 2 字节 (大端)
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// ============================================================
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static int i2c_read_word(ads1115_t *dev, uint8_t reg, uint16_t *value)
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{
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// 先写入寄存器地址
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if (write(dev->fd, ®, 1) != 1) {
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perror("I2C 设置寄存器地址失败");
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return -1;
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}
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// 读取 2 字节
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uint8_t buf[2];
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if (read(dev->fd, buf, 2) != 2) {
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perror("I2C 读失败");
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return -1;
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}
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*value = ((uint16_t)buf[0] << 8) | buf[1];
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return 0;
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}
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// ============================================================
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// 写配置寄存器
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// ============================================================
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static int ads1115_write_config(ads1115_t *dev, uint16_t config)
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{
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dev->config = config;
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return i2c_write_word(dev, ADS1115_REG_CONFIG, config);
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}
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// ============================================================
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// 读配置寄存器
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// ============================================================
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static int ads1115_read_config(ads1115_t *dev, uint16_t *config)
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{
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return i2c_read_word(dev, ADS1115_REG_CONFIG, config);
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}
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// ============================================================
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// 读转换结果寄存器
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// ============================================================
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static int ads1115_read_conversion(ads1115_t *dev, int16_t *value)
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{
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uint16_t raw;
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int ret = i2c_read_word(dev, ADS1115_REG_CONVERSION, &raw);
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if (ret == 0) {
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*value = (int16_t)raw;
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}
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return ret;
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}
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// ============================================================
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// 读阈值寄存器
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// ============================================================
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static int ads1115_read_thresh(ads1115_t *dev, int16_t *lo, int16_t *hi)
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{
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uint16_t raw_lo, raw_hi;
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if (i2c_read_word(dev, ADS1115_REG_LO_THRESH, &raw_lo) < 0) return -1;
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if (i2c_read_word(dev, ADS1115_REG_HI_THRESH, &raw_hi) < 0) return -1;
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*lo = (int16_t)raw_lo;
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*hi = (int16_t)raw_hi;
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return 0;
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}
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// ============================================================
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// 写阈值寄存器
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// ============================================================
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static int ads1115_write_thresh(ads1115_t *dev, int16_t lo, int16_t hi)
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{
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if (i2c_write_word(dev, ADS1115_REG_LO_THRESH, (uint16_t)lo) < 0) return -1;
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if (i2c_write_word(dev, ADS1115_REG_HI_THRESH, (uint16_t)hi) < 0) return -1;
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return 0;
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}
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// ============================================================
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// 初始化 ADS1115
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//
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// pga_idx: 0~5 对应 ADS1115_PGA_xxx
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// dr_idx: 0~7 对应 ADS1115_DR_xxx
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// ============================================================
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static int ads1115_init(ads1115_t *dev, int pga_idx, int dr_idx)
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{
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if (pga_idx < 0 || pga_idx > 5) pga_idx = 2; // 默认 ±2.048V
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if (dr_idx < 0 || dr_idx > 7) dr_idx = 4; // 默认 128SPS
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dev->fs_voltage = pga_fs[pga_idx];
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// 构建配置:
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// - 单次转换模式
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// - 禁用比较器
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// - 默认通道 AIN0-GND
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uint16_t config = ADS1115_MUX_AIN0_GND // 单端 AIN0
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| (pga_idx << 9) // PGA
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| ADS1115_MODE_SINGLE // 单次模式
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| (dr_idx << 5) // 数据速率
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| ADS1115_COMP_QUE_DISABLE; // 禁用比较器
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int ret = ads1115_write_config(dev, config);
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if (ret < 0) return ret;
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printf("ADS1115 初始化完成: ");
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printf("PGA=%s, 速率=%s, 满量程=%.3fV\n",
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pga_names[pga_idx], dr_names[dr_idx], dev->fs_voltage);
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return 0;
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}
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// ============================================================
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// 读取单端通道 (单次转换)
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// ch: 0~3 对应 AIN0~AIN3
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// ============================================================
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static double ads1115_read_single(ads1115_t *dev, int ch)
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{
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if (ch < 0 || ch > 3) {
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fprintf(stderr, "通道号无效: %d (有效: 0~3)\n", ch);
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return 0.0;
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}
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// 1. 重写配置: 设置通道 + 启动转换
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uint16_t mux = ADS1115_MUX_AIN0_GND | (ch << 12); // AINch-GND
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uint16_t config = (dev->config & ~0x7000) // 清除 MUX 位
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| mux
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| ADS1115_OS_START; // 启动单次转换
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ads1115_write_config(dev, config);
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// 2. 等待转换完成 (OS 位被硬件清 0)
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// 根据数据速率等待足够时间
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uint16_t dr_idx = (config >> 5) & 0x07;
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int wait_ms = 1000 / (8 << dr_idx) + 1; // 保守估计
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delay_ms(wait_ms + 2);
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// 3. 读转换值
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int16_t raw = 0;
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if (ads1115_read_conversion(dev, &raw) < 0) {
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return 0.0;
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}
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// 4. 转换为电压
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// ADS1115 16位有符号, 满量程 = FS_VOLTAGE
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// V = raw * FS_VOLTAGE / 32768
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double voltage = (double)raw * dev->fs_voltage / 32768.0;
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return voltage;
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}
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// ============================================================
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// 读取差分通道 (单次转换)
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// pos: 正极通道 (0~3)
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// neg: 负极通道 (0~3)
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// ============================================================
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static double ads1115_read_diff(ads1115_t *dev, int pos, int neg)
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{
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if (pos < 0 || pos > 3 || neg < 0 || neg > 3) {
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fprintf(stderr, "通道号无效\n");
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return 0.0;
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}
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// 构建 MUX 值 (差分)
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// AIN0-AIN1: 0, AIN0-AIN3: 1, AIN1-AIN3: 2, AIN2-AIN3: 3
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uint16_t mux_val;
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if (pos == 0 && neg == 1) mux_val = 0;
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else if (pos == 0 && neg == 3) mux_val = 1;
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else if (pos == 1 && neg == 3) mux_val = 2;
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else if (pos == 2 && neg == 3) mux_val = 3;
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else {
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fprintf(stderr, "不支持的差分组合: AIN%d - AIN%d\n", pos, neg);
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fprintf(stderr, "支持: 0-1, 0-3, 1-3, 2-3\n");
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return 0.0;
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}
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uint16_t mux = mux_val << 12;
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uint16_t config = (dev->config & ~0x7000)
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| mux
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| ADS1115_OS_START;
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ads1115_write_config(dev, config);
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uint16_t dr_idx = (config >> 5) & 0x07;
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int wait_ms = 1000 / (8 << dr_idx) + 1;
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delay_ms(wait_ms + 2);
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int16_t raw = 0;
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if (ads1115_read_conversion(dev, &raw) < 0) {
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return 0.0;
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}
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double voltage = (double)raw * dev->fs_voltage / 32768.0;
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return voltage;
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}
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// ============================================================
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// 连续模式读数 (需先配置为连续模式)
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// ============================================================
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static int ads1115_start_continuous(ads1115_t *dev, int ch)
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{
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if (ch < 0 || ch > 3) return -1;
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uint16_t config = (dev->config & ~0x7100) // 清除 MUX+MODE 位
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| (ADS1115_MUX_AIN0_GND | (ch << 12)) // 通道
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| ADS1115_MODE_CONTINUOUS // 连续模式
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| ADS1115_COMP_QUE_DISABLE;
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return ads1115_write_config(dev, config);
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}
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// ============================================================
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// 连续模式读数
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// ============================================================
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static double ads1115_read_continuous(ads1115_t *dev)
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{
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int16_t raw = 0;
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if (ads1115_read_conversion(dev, &raw) < 0) {
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return 0.0;
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}
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return (double)raw * dev->fs_voltage / 32768.0;
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}
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// ============================================================
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// 扫描所有单端通道
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// ============================================================
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static void ads1115_scan_all(ads1115_t *dev)
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{
|
|
printf("\n===== 单端通道扫描 =====\n");
|
|
const char *ch_names[] = {"AIN0", "AIN1", "AIN2", "AIN3"};
|
|
for (int ch = 0; ch < 4; ch++) {
|
|
double v = ads1115_read_single(dev, ch);
|
|
printf(" %s: %+.6f V\n", ch_names[ch], v);
|
|
}
|
|
}
|
|
|
|
// ============================================================
|
|
// 打印当前配置
|
|
// ============================================================
|
|
static void ads1115_print_config(ads1115_t *dev)
|
|
{
|
|
uint16_t config;
|
|
if (ads1115_read_config(dev, &config) < 0) return;
|
|
|
|
int mux = (config >> 12) & 0x07;
|
|
int pga = (config >> 9) & 0x07;
|
|
int mode = (config >> 8) & 0x01;
|
|
int dr = (config >> 5) & 0x07;
|
|
int comp = config & 0x03;
|
|
|
|
printf("\n===== ADS1115 寄存器 =====\n");
|
|
printf(" 配置寄存器: 0x%04X\n", config);
|
|
printf(" MUX: %d (", mux);
|
|
switch (mux) {
|
|
case 0: printf("AIN0-AIN1"); break;
|
|
case 1: printf("AIN0-AIN3"); break;
|
|
case 2: printf("AIN1-AIN3"); break;
|
|
case 3: printf("AIN2-AIN3"); break;
|
|
case 4: printf("AIN0-GND"); break;
|
|
case 5: printf("AIN1-GND"); break;
|
|
case 6: printf("AIN2-GND"); break;
|
|
case 7: printf("AIN3-GND"); break;
|
|
}
|
|
printf(")\n");
|
|
printf(" PGA: %d -> %s (满量程 %.3fV)\n", pga,
|
|
(pga <= 5) ? pga_names[pga] : "未知",
|
|
(pga <= 5) ? pga_fs[pga] : 0);
|
|
printf(" 模式: %s\n", mode ? "单次" : "连续");
|
|
printf(" 速率: %d -> %s\n", dr, dr_names[dr & 0x07]);
|
|
printf(" 比较器: %s\n", comp == 3 ? "禁用" : "启用");
|
|
|
|
// 读阈值
|
|
int16_t lo, hi;
|
|
if (ads1115_read_thresh(dev, &lo, &hi) == 0) {
|
|
printf(" 阈值: LO=%d (%.6fV), HI=%d (%.6fV)\n",
|
|
lo, (double)lo * dev->fs_voltage / 32768.0,
|
|
hi, (double)hi * dev->fs_voltage / 32768.0);
|
|
}
|
|
}
|
|
|
|
// ============================================================
|
|
// 打印转换结果
|
|
// ============================================================
|
|
static void print_reading(const char *label, double voltage)
|
|
{
|
|
printf(" %s: %+.6f V (%.3f mV)\n", label, voltage, voltage * 1000.0);
|
|
}
|
|
|
|
// ============================================================
|
|
// 打印帮助
|
|
// ============================================================
|
|
static void print_help(const char *prog)
|
|
{
|
|
printf("\n用法: %s [I2C地址] [PGA] [数据速率]\n", prog);
|
|
printf("\n参数 (可选):\n");
|
|
printf(" I2C地址 0x48~0x4B (默认 0x48)\n");
|
|
printf(" PGA 0~5 (默认 2 = ±2.048V)\n");
|
|
printf(" 0=±6.144V, 1=±4.096V, 2=±2.048V\n");
|
|
printf(" 3=±1.024V, 4=±0.512V, 5=±0.256V\n");
|
|
printf(" 数据速率 0~7 (默认 4 = 128SPS)\n");
|
|
printf(" 0=8, 1=16, 2=32, 3=64\n");
|
|
printf(" 4=128, 5=250, 6=475, 7=860 (SPS)\n");
|
|
printf("\n示例:\n");
|
|
printf(" %s\n", prog);
|
|
printf(" %s 0x49\n", prog);
|
|
printf(" %s 0x48 2 6\n", prog);
|
|
}
|
|
|
|
// ============================================================
|
|
// 主函数
|
|
// ============================================================
|
|
int main(int argc, char *argv[])
|
|
{
|
|
ads1115_t dev;
|
|
uint8_t addr = ADS1115_ADDR;
|
|
int pga = 2; // ±2.048V
|
|
int dr = 4; // 128 SPS
|
|
|
|
// 解析命令行参数
|
|
if (argc >= 2) {
|
|
if (strcmp(argv[1], "-h") == 0 || strcmp(argv[1], "--help") == 0) {
|
|
print_help(argv[0]);
|
|
return 0;
|
|
}
|
|
addr = (uint8_t)strtol(argv[1], NULL, 0);
|
|
}
|
|
if (argc >= 3) pga = atoi(argv[2]);
|
|
if (argc >= 4) dr = atoi(argv[3]);
|
|
|
|
printf("ADS1115 Linux I2C 采集示例\n");
|
|
printf("============================\n\n");
|
|
|
|
// 1. 初始化 I2C
|
|
if (i2c_init(&dev, I2C_DEVICE, addr) < 0) {
|
|
return 1;
|
|
}
|
|
|
|
// 2. 初始化 ADS1115
|
|
if (ads1115_init(&dev, pga, dr) < 0) {
|
|
close(dev.fd);
|
|
return 1;
|
|
}
|
|
|
|
// 3. 单通道测试 (AIN0)
|
|
printf("\n===== 单通道测试 (AIN0, 连续读 10 次) =====\n");
|
|
for (int i = 0; i < 10; i++) {
|
|
double v = ads1115_read_single(&dev, 0);
|
|
char label[32];
|
|
snprintf(label, sizeof(label), "[%d]", i);
|
|
print_reading(label, v);
|
|
delay_ms(10);
|
|
}
|
|
|
|
// 4. 扫描所有单端通道
|
|
ads1115_scan_all(&dev);
|
|
|
|
// 5. 差分模式示例
|
|
printf("\n===== 差分测试 (AIN0 - AIN1) =====\n");
|
|
for (int i = 0; i < 5; i++) {
|
|
double v = ads1115_read_diff(&dev, 0, 1);
|
|
char label[32];
|
|
snprintf(label, sizeof(label), "[%d]", i);
|
|
print_reading(label, v);
|
|
delay_ms(10);
|
|
}
|
|
|
|
// 6. 连续模式测试
|
|
printf("\n===== 连续模式测试 (AIN0, 5 次) =====\n");
|
|
if (ads1115_start_continuous(&dev, 0) == 0) {
|
|
delay_ms(50); // 等第一次转换完成
|
|
for (int i = 0; i < 5; i++) {
|
|
double v = ads1115_read_continuous(&dev);
|
|
char label[32];
|
|
snprintf(label, sizeof(label), "[%d] 连续", i);
|
|
print_reading(label, v);
|
|
delay_ms(10);
|
|
}
|
|
} else {
|
|
printf(" 启动连续模式失败\n");
|
|
}
|
|
|
|
// 7. 打印配置信息
|
|
ads1115_print_config(&dev);
|
|
|
|
// 8. 清理
|
|
close(dev.fd);
|
|
printf("\n程序结束.\n");
|
|
|
|
return 0;
|
|
}
|