#!/usr/bin/env python3 """ ADS1256: Linux SPI 读取 TI ADS1256 24位 ΔΣ ADC 的命令行工具 """ import spidev import os import sys import argparse import time # ============================================================ # ADS1256 寄存器地址 # ============================================================ ADS1256_REG_STATUS = 0x00 ADS1256_REG_MUX = 0x01 ADS1256_REG_ADCON = 0x02 ADS1256_REG_DRATE = 0x03 ADS1256_REG_IO = 0x04 ADS1256_REG_OFC0 = 0x05 ADS1256_REG_OFC1 = 0x06 ADS1256_REG_OFC2 = 0x07 ADS1256_REG_FSC0 = 0x08 ADS1256_REG_FSC1 = 0x09 ADS1256_REG_FSC2 = 0x0A # ============================================================ # ADS1256 命令 # ============================================================ ADS1256_CMD_WAKEUP = 0x00 ADS1256_CMD_RDATA = 0x01 ADS1256_CMD_RDATAC = 0x03 ADS1256_CMD_SDATAC = 0x0F ADS1256_CMD_RREG = 0x10 ADS1256_CMD_WREG = 0x50 ADS1256_CMD_SELFCAL = 0xF0 ADS1256_CMD_SELFOCAL = 0xF1 ADS1256_CMD_SELFGCAL = 0xF2 ADS1256_CMD_SYSOCAL = 0xF3 ADS1256_CMD_SYSGCAL = 0xF4 ADS1256_CMD_SYNC = 0xFC ADS1256_CMD_STANDBY = 0xFD ADS1256_CMD_RESET = 0xFE # ============================================================ # 数据速率 (DRATE 寄存器值) # ============================================================ DRATE_MAP = { 30000: 0xF0, 15000: 0xE0, 7500: 0xD0, 3750: 0xC0, 2000: 0xB0, 1000: 0xA0, 500: 0x90, 100: 0x80, 60: 0x70, 50: 0x60, 30: 0x50, 25: 0x40, 15: 0x30, 10: 0x20, 5: 0x10, } # ============================================================ # PGA 增益 # ============================================================ PGA_MAP = {1: 0x00, 2: 0x01, 4: 0x02, 8: 0x03, 16: 0x04, 32: 0x05, 64: 0x06} VREF = 2.5 # 参考电压 # ============================================================ # SPI 接口类 (基于 spidev) # ============================================================ class SpiDev: def __init__(self, device="/dev/spidev0.0", speed=1920000): self.device = device self.speed = speed self.spi = None self._bus = None self._cs = None def _parse_device(self): """从设备路径解析 bus 和 cs, 如 /dev/spidev0.0 -> (0, 0)""" base = os.path.basename(self.device) # spidev0.0 parts = base.replace("spidev", "").split(".") return int(parts[0]), int(parts[1]) def open(self): self._bus, self._cs = self._parse_device() self.spi = spidev.SpiDev() self.spi.open(self._bus, self._cs) self.spi.mode = 1 # SPI 模式 1: CPOL=0, CPHA=1 self.spi.bits_per_word = 8 self.spi.max_speed_hz = self.speed # 读取验证 print(f"SPI 初始化: {self.device}, 模式={self.spi.mode}, " f"位数={self.spi.bits_per_word}, 速度={self.spi.max_speed_hz} Hz", file=sys.stderr) def transfer(self, tx_data, rx_len=None): """SPI 全双工传输""" if rx_len is None: rx_len = len(tx_data) # spidev.xfer2 返回接收到的字节 rx = self.spi.xfer2(list(tx_data), self.speed, 1) # 1 = SPI_MODE_1 # 如果 rx_len 大于发送长度，补充虚拟字节 if rx_len > len(tx_data): extra = self.spi.xfer2([0xFF] * (rx_len - len(tx_data)), self.speed, 1) rx.extend(extra) return list(rx[:rx_len]) def write_byte(self, byte): self.spi.xfer2([byte], self.speed, 1) # 不需要接收 def read_byte(self): rx = self.spi.xfer2([0xFF], self.speed, 1) return rx[0] def close(self): if self.spi: self.spi.close() self.spi = None # ============================================================ # ADS1256 控制类 # ============================================================ class ADS1256: def __init__(self, spi, pga=2, drate=1000): self.spi = spi self.pga = pga self.drate = drate self.pga_reg = PGA_MAP.get(pga, 0x01) def wait_drdy(self): time.sleep(0.0001) # 100us 模拟等待 def reset(self): self.spi.write_byte(ADS1256_CMD_RESET) time.sleep(0.001) self.spi.write_byte(ADS1256_CMD_WAKEUP) time.sleep(0.001) def write_reg(self, reg, value): self.spi.write_byte(ADS1256_CMD_WREG | reg) self.spi.write_byte(0x00) # 1 byte self.spi.write_byte(value) def read_reg(self, reg): self.spi.write_byte(ADS1256_CMD_RREG | reg) self.spi.write_byte(0x00) return self.spi.read_byte() def set_channel(self, pos, neg=0x08): """设置输入通道, neg=0x08 表示 AINCOM (单端模式)""" mux = ((pos & 0x07) << 4) | (neg & 0x07) self.write_reg(ADS1256_REG_MUX, mux) time.sleep(0.00001) def init(self): print("初始化 ADS1256...", file=sys.stderr) # 复位 self.reset() time.sleep(0.01) # STATUS: ACAL=1 (自动校准), ORDER=0 (MSB), BUFEN=0 self.write_reg(ADS1256_REG_STATUS, 0x14) # MUX: 默认 AIN0 + AINCOM self.set_channel(0, 0x08) # ADCON: PGA 增益 self.write_reg(ADS1256_REG_ADCON, self.pga_reg) # DRATE: 数据速率 drate_val = DRATE_MAP.get(self.drate, 0xA0) self.write_reg(ADS1256_REG_DRATE, drate_val) # 自校准 print("自校准中...", file=sys.stderr) self.spi.write_byte(ADS1256_CMD_SELFCAL) time.sleep(0.5) # 等待校准完成 (~400ms @ 1000SPS) # 验证寄存器 status = self.read_reg(ADS1256_REG_STATUS) mux = self.read_reg(ADS1256_REG_MUX) adcon = self.read_reg(ADS1256_REG_ADCON) drate = self.read_reg(ADS1256_REG_DRATE) print(f"寄存器: STATUS=0x{status:02X}, MUX=0x{mux:02X}, " f"ADCON=0x{adcon:02X}, DRATE=0x{drate:02X}", file=sys.stderr) print("ADS1256 初始化完成!", file=sys.stderr) def read_data(self): """单次读取 24 位数据, 返回有符号整数值""" self.wait_drdy() self.spi.write_byte(ADS1256_CMD_RDATA) buf = self.spi.transfer([0xFF, 0xFF, 0xFF], 3) # 组合 24 位 value = (buf[0] << 16) | (buf[1] << 8) | buf[2] # 符号扩展 (24 位 -> 32 位) if value & 0x800000: value |= 0xFF000000 # Python 中转为有符号 if value >= 0x80000000: value -= 0x100000000 return value def raw_to_voltage(self, raw): """将原始值转换为电压""" return raw * VREF / (1 << 23) / self.pga def read_channel(self, ch): """读取指定单端通道""" self.set_channel(ch, 0x08) # AINch vs AINCOM time.sleep(0.00001) self.spi.write_byte(ADS1256_CMD_SYNC) time.sleep(0.00001) self.spi.write_byte(ADS1256_CMD_WAKEUP) # 等待转换完成 (1000SPS = 1ms) time.sleep(0.002) return self.read_data() def read_diff(self, pos, neg): """读取差分通道""" self.set_channel(pos, neg) time.sleep(0.00001) self.spi.write_byte(ADS1256_CMD_SYNC) time.sleep(0.00001) self.spi.write_byte(ADS1256_CMD_WAKEUP) time.sleep(0.002) return self.read_data() def scan_all(self): """扫描所有 8 个单端通道""" results = [] for ch in range(8): raw = self.read_channel(ch) volts = self.raw_to_voltage(raw) results.append((ch, raw, volts)) return results # ============================================================ # 主程序 # ============================================================ def main(): parser = argparse.ArgumentParser( description="ADS1256: Linux SPI 读取 TI ADS1256 24位 ΔΣ ADC 的命令行工具", formatter_class=argparse.RawDescriptionHelpFormatter, epilog=""" 参数说明: -d, --device SPI 设备路径 (默认: /dev/spidev0.0) -s, --speed SPI 时钟频率 (Hz) (默认: 1920000) -m, --mode 工作模式: single/diff/scan (默认: single) -c, --channel 单端通道号 0-7 (默认: 0) --pos 差分正端 0-7 (默认: 0) --neg 差分负端 0-7 (默认: 1) -p, --pga PGA 增益 1/2/4/8/16/32/64 (默认: 2) -r, --drate 数据速率 SPS (默认: 1000) 可选: 5,10,15,25,30,50,60,100,500,1000, 2000,3750,7500,15000,30000 -n, --count 采样次数 (默认: 1) --avg 输出均值 (多采样时) -o, --output 输出格式: raw/voltage/both (默认: both) 使用示例: # 读取 AIN0 单端通道 ads1256 -c 0 # 读取 AIN0 差分 AIN1 ads1256 -m diff --pos 0 --neg 1 # 扫描所有 8 个通道 ads1256 -m scan # 设置 PGA=1, 速率为 30SPS, 采样 10 次并输出均值 ads1256 -c 0 -p 1 -r 30 -n 10 --avg # 指定 SPI 设备 ads1256 -d /dev/spidev0.1 -s 1000000 -c 3 """ ) parser.add_argument("-d", "--device", default="/dev/spidev0.0", help="SPI 设备路径 (默认: /dev/spidev0.0)") parser.add_argument("-s", "--speed", type=int, default=1920000, help="SPI 时钟频率 Hz (默认: 1920000)") parser.add_argument("-m", "--mode", choices=["single", "diff", "scan"], default="single", help="工作模式 (默认: single)") parser.add_argument("-c", "--channel", type=int, default=0, choices=range(8), help="单端通道号 0-7 (默认: 0)") parser.add_argument("--pos", type=int, default=0, choices=range(8), help="差分正端 0-7 (默认: 0)") parser.add_argument("--neg", type=int, default=1, choices=range(8), help="差分负端 0-7 (默认: 1)") parser.add_argument("-p", "--pga", type=int, default=2, choices=[1, 2, 4, 8, 16, 32, 64], help="PGA 增益 (默认: 2)") parser.add_argument("-r", "--drate", type=int, default=1000, help="数据速率 SPS (默认: 1000)") parser.add_argument("-n", "--count", type=int, default=1, help="采样次数 (默认: 1)") parser.add_argument("--avg", action="store_true", help="输出均值") parser.add_argument("-o", "--output", choices=["raw", "voltage", "both"], default="both", help="输出格式 (默认: both)") args = parser.parse_args() # 验证 drate if args.drate not in DRATE_MAP: print(f"错误: 不支持的数据速率 {args.drate} SPS", file=sys.stderr) print(f"支持: {sorted(DRATE_MAP.keys())}", file=sys.stderr) sys.exit(1) # 验证 SPI 设备 if not os.path.exists(args.device): print(f"错误: SPI 设备 {args.device} 不存在", file=sys.stderr) sys.exit(1) # 初始化 SPI spi = SpiDev(device=args.device, speed=args.speed) try: spi.open() except Exception as e: print(f"错误: SPI 初始化失败 - {e}", file=sys.stderr) sys.exit(1) # 初始化 ADS1256 adc = ADS1256(spi, pga=args.pga, drate=args.drate) try: adc.init() except Exception as e: print(f"ADS1256 初始化失败: {e}", file=sys.stderr) spi.close() sys.exit(1) # 执行读取 try: if args.mode == "scan": # 扫描所有通道 results = adc.scan_all() print("\n===== 多通道扫描 =====") for ch, raw, volts in results: _print_result(ch, raw, volts, args.output) elif args.mode == "diff": # 差分模式 pos, neg = args.pos, args.neg channel_label = f"AIN{pos}-AIN{neg}" raw_values = [] for i in range(args.count): raw = adc.read_diff(pos, neg) raw_values.append(raw) volts = adc.raw_to_voltage(raw) _print_sample(i, raw, volts, args.output, channel_label) if args.count > 1 and args.avg: avg_raw = sum(raw_values) // len(raw_values) avg_volts = adc.raw_to_voltage(avg_raw) print(f"\n--- 均值 ---") _print_result(channel_label, avg_raw, avg_volts, args.output) else: # 单端模式 ch = args.channel channel_label = f"AIN{ch}" raw_values = [] for i in range(args.count): raw = adc.read_channel(ch) raw_values.append(raw) volts = adc.raw_to_voltage(raw) _print_sample(i, raw, volts, args.output, channel_label) if args.count > 1 and args.avg: avg_raw = sum(raw_values) // len(raw_values) avg_volts = adc.raw_to_voltage(avg_raw) print(f"\n--- 均值 ---") _print_result(channel_label, avg_raw, avg_volts, args.output) except Exception as e: print(f"读取错误: {e}", file=sys.stderr) finally: spi.close() def _print_sample(index, raw, volts, output_format, label=""): if output_format == "raw": print(f"[{index}] {label}: raw={raw}") elif output_format == "voltage": print(f"[{index}] {label}: {_fmt_voltage(volts)}") else: print(f"[{index}] {label}: raw={raw:7d}, {_fmt_voltage(volts)}") def _print_result(label, raw, volts, output_format): if output_format == "raw": print(f" {label}: raw={raw}") elif output_format == "voltage": print(f" {label}: {_fmt_voltage(volts)}") else: print(f" {label}: raw={raw:7d}, {_fmt_voltage(volts)}") def _fmt_voltage(volts): if abs(volts) >= 1.0: return f"电压 = {volts:+.6f} V" else: return f"电压 = {volts*1000:+.4f} mV" if __name__ == "__main__": main()