AD5933测量阻抗的原理图

AD5933是一款用于测量阻抗的集成电路，其原理图如下所示：


AD5933采用了外接的电压控制振荡器（VCO），通过控制VCO的频率变化来改变测量电路的频率。同时，它还集成了一个12位的模数转换器（ADC），可以将测量电路输出的信号转换为数字信号，进而进行处理和分析。

在测量时，AD5933会通过DAC输出一段特定的扫频信号，然后将这个信号送入被测阻抗（或电容）中，测量得到被测阻抗的阻抗值。具体的测量流程可参考AD5933的数据手册。

相关问题

AD5933测量阻抗的代码

AD5933是一款用于测量阻抗的芯片，以下是使用Arduino控制AD5933进行阻抗测量的示例代码：

#include <Wire.h>

#define AD5933_ADDR 0x0D // I2C地址为0x0D
#define AD5933_CTRL_REG1 0x80 // 控制寄存器1地址
#define AD5933_CTRL_REG2 0x81 // 控制寄存器2地址
#define AD5933_START_FREQ_REG 0x82 // 起始频率寄存器地址
#define AD5933_FREQ_INC_REG 0x85 // 频率增量寄存器地址
#define AD5933_NUM_INCREMENTS_REG 0x88 // 增量数寄存器地址
#define AD5933_CTRL_REG3 0x8A // 控制寄存器3地址
#define AD5933_STATUS_REG 0x8F // 状态寄存器地址
#define AD5933_REAL_REG 0x94 // 实部数据寄存器地址
#define AD5933_IMAG_REG 0x96 // 虚部数据寄存器地址

byte gainFactor = 1; // 增益因子
byte rangeControl = 0; // 测量范围控制
float VREF = 3.3; // 参考电压

void setup() {
  Wire.begin();
  Serial.begin(9600);

  // 设置控制寄存器1
  byte ctrlReg1 = 0x10; // 使用外部时钟源
  writeRegister(AD5933_CTRL_REG1, ctrlReg1);

  // 设置控制寄存器2
  byte ctrlReg2 = 0x00; // 禁用内部系统校准
  writeRegister(AD5933_CTRL_REG2, ctrlReg2);

  // 设置起始频率为1kHz
  long startFreq = 1000;
  byte startFreqReg[3];
  convertToRegister(startFreq, startFreqReg);
  writeRegister(AD5933_START_FREQ_REG, startFreqReg[0]);
  writeRegister(AD5933_START_FREQ_REG + 1, startFreqReg[1]);
  writeRegister(AD5933_START_FREQ_REG + 2, startFreqReg[2]);

  // 设置频率增量为1kHz
  long freqInc = 1000;
  byte freqIncReg[3];
  convertToRegister(freqInc, freqIncReg);
  writeRegister(AD5933_FREQ_INC_REG, freqIncReg[0]);
  writeRegister(AD5933_FREQ_INC_REG + 1, freqIncReg[1]);
  writeRegister(AD5933_FREQ_INC_REG + 2, freqIncReg[2]);

  // 设置增量数为1
  byte numIncrements = 0x01;
  writeRegister(AD5933_NUM_INCREMENTS_REG, numIncrements);

  // 设置控制寄存器3
  byte ctrlReg3 = 0x00; // 测量阻抗
  writeRegister(AD5933_CTRL_REG3, ctrlReg3);
}

void loop() {
  // 开始测量
  byte ctrlReg1 = readRegister(AD5933_CTRL_REG1);
  writeRegister(AD5933_CTRL_REG1, ctrlReg1 | 0x01); // 设置控制寄存器1的LSB

  // 等待测量完成
  while (!(readRegister(AD5933_STATUS_REG) & 0x02)) {}

  // 读取测量结果
  byte realData[2];
  byte imagData[2];
  readRegister(AD5933_REAL_REG, realData, 2);
  readRegister(AD5933_IMAG_REG, imagData, 2);

  long real = (long)(realData[0] << 8 | realData[1]);
  long imag = (long)(imagData[0] << 8 | imagData[1]);

  // 计算阻抗值
  float magnitude = sqrt(real * real + imag * imag);
  float impedance = magnitude / (gainFactor * rangeControl * VREF);

  Serial.println(impedance);
  delay(1000);
}

// 将长整型数值转换为3个字节的寄存器值
void convertToRegister(long value, byte* reg) {
  reg[0] = (byte)(value >> 16);
  reg[1] = (byte)(value >> 8);
  reg[2] = (byte)value;
}

// 读取指定地址的寄存器值
byte readRegister(byte regAddr) {
  Wire.beginTransmission(AD5933_ADDR);
  Wire.write(regAddr);
  Wire.endTransmission(false);
  Wire.requestFrom(AD5933_ADDR, 1);
  return Wire.read();
}

// 读取指定地址和长度的寄存器值
void readRegister(byte regAddr, byte* data, int length) {
  Wire.beginTransmission(AD5933_ADDR);
  Wire.write(regAddr);
  Wire.endTransmission(false);
  Wire.requestFrom(AD5933_ADDR, length);
  for (int i = 0; i < length; i++) {
    data[i] = Wire.read();
  }
}

// 写入指定地址的寄存器值
void writeRegister(byte regAddr, byte value) {
  Wire.beginTransmission(AD5933_ADDR);
  Wire.write(regAddr);
  Wire.write(value);
  Wire.endTransmission();
}

// 写入指定地址和长度的寄存器值
void writeRegister(byte regAddr, byte* data, int length) {
  Wire.beginTransmission(AD5933_ADDR);
  Wire.write(regAddr);
  for (int i = 0; i < length; i++) {
    Wire.write(data[i]);
  }
  Wire.endTransmission();
}

该代码使用了Arduino的Wire库来进行I2C通信，通过读写AD5933的寄存器来控制芯片的工作模式和获取测量结果。在循环中不断地进行阻抗测量，并将计算得到的阻抗值打印到串口上。需要注意的是，该代码并没有对AD5933的增益因子和测量范围进行设置，需要根据实际应用需求进行调整。

AD5933测量阻抗代码

以下是AD5933测量阻抗的示例代码，供参考：

import smbus
import time
import math
 
# AD5933 Registers
ADDR = 0x0D
REG_CTRL_HB = 0x80
REG_CTRL_LB = 0x81
REG_FREQ_START = 0x82
REG_FREQ_INC = 0x85
REG_NUM_INC = 0x88
REG_NUM_SETTLE = 0x8A
REG_STATUS = 0x8F
REG_REAL_DATA = 0x94
REG_IMAG_DATA = 0x96
 
# AD5933 Control Register High Byte Bits
CTRL_HB_INIT_START_FREQ = 0x10
CTRL_HB_START_SWEEP = 0x20
CTRL_HB_INC_FREQ = 0x30
CTRL_HB_REPEAT_FREQ = 0x40
CTRL_HB_MEASURE_TEMP = 0x80
 
# AD5933 Control Register Low Byte Bits
CTRL_LB_RANGE_2000 = 0x00
CTRL_LB_RANGE_200 = 0x01
CTRL_LB_RANGE_20 = 0x02
CTRL_LB_RANGE_2 = 0x03
CTRL_LB_PGA_GAIN_1 = 0x00
CTRL_LB_PGA_GAIN_5 = 0x04
CTRL_LB_PGA_GAIN_10 = 0x08
CTRL_LB_PGA_GAIN_50 = 0x0C
CTRL_LB_PGA_GAIN_100 = 0x10
CTRL_LB_PGA_GAIN_200 = 0x14
CTRL_LB_PGA_GAIN_400 = 0x18
CTRL_LB_PGA_GAIN_1000 = 0x1C
CTRL_LB_SYNC_OUT = 0x20
CTRL_LB_SYNC_IN_TEMP = 0x40
 
class AD5933:
 
    def __init__(self, bus, address=ADDR):
        self.bus = smbus.SMBus(bus)
        self.address = address
        self.gain = 1
        self.range = 2000
 
    def reset(self):
        self.bus.write_byte_data(self.address, REG_CTRL_HB, 0x10)
 
    def set_range(self, range):
        self.range = range
        self.bus.write_byte_data(self.address, REG_CTRL_LB, self.range)
 
    def set_gain(self, gain):
        self.gain = gain
        self.bus.write_byte_data(self.address, REG_CTRL_LB, self.gain)
 
    def set_frequency(self, freq):
        freq_word = int(freq * 2**27 / 16000000)
        self.bus.write_byte_data(self.address, REG_FREQ_START, (freq_word & 0xFF0000) >> 16)
        self.bus.write_byte_data(self.address, REG_FREQ_START + 1, (freq_word & 0x00FF00) >> 8)
        self.bus.write_byte_data(self.address, REG_FREQ_START + 2, (freq_word & 0x0000FF))
 
    def set_increment(self, inc):
        inc_word = int(inc * 2**27 / 16000000)
        self.bus.write_byte_data(self.address, REG_FREQ_INC, (inc_word & 0xFF0000) >> 16)
        self.bus.write_byte_data(self.address, REG_FREQ_INC + 1, (inc_word & 0x00FF00) >> 8)
        self.bus.write_byte_data(self.address, REG_FREQ_INC + 2, (inc_word & 0x0000FF))
 
    def set_num_increments(self, num):
        self.bus.write_byte_data(self.address, REG_NUM_INC, (num & 0xFF00) >> 8)
        self.bus.write_byte_data(self.address, REG_NUM_INC + 1, (num & 0x00FF))
 
    def set_num_settling_cycles(self, num):
        self.bus.write_byte_data(self.address, REG_NUM_SETTLE, num)
 
    def start_sweep(self):
        ctrl_hb = CTRL_HB_INIT_START_FREQ | CTRL_HB_START_SWEEP | CTRL_HB_INC_FREQ
        self.bus.write_byte_data(self.address, REG_CTRL_HB, ctrl_hb)
 
    def get_status(self):
        return self.bus.read_byte_data(self.address, REG_STATUS)
 
    def wait_for_status(self, mask):
        while True:
            status = self.get_status()
            if (status & mask) == mask:
                break
            time.sleep(0.1)
 
    def get_real(self):
        real_data = self.bus.read_byte_data(self.address, REG_REAL_DATA)
        real_data |= self.bus.read_byte_data(self.address, REG_REAL_DATA + 1) << 8
        if (real_data & 0x8000) > 0:
            real_data -= 65536
        return real_data
 
    def get_imaginary(self):
        imag_data = self.bus.read_byte_data(self.address, REG_IMAG_DATA)
        imag_data |= self.bus.read_byte_data(self.address, REG_IMAG_DATA + 1) << 8
        if (imag_data & 0x8000) > 0:
            imag_data -= 65536
        return imag_data
 
    def get_magnitude(self):
        real = self.get_real()
        imag = self.get_imaginary()
        return math.sqrt(real**2 + imag**2) / 2**15 * self.range / self.gain
 
    def get_phase(self):
        real = self.get_real()
        imag = self.get_imaginary()
        phase = math.atan2(imag, real) * 180 / math.pi
        if phase < 0:
            phase += 360
        return phase
 
    def measure_impedance(self, freq, gain=1, range=2000, num_increments=10, num_settling_cycles=10):
        self.set_gain(gain)
        self.set_range(range)
        self.set_frequency(freq)
        self.set_increment(freq / num_increments)
        self.set_num_increments(num_increments)
        self.set_num_settling_cycles(num_settling_cycles)
        self.start_sweep()
        self.wait_for_status(0x02)
        return self.get_magnitude(), self.get_phase()

使用方法：

# 初始化AD5933
ad5933 = AD5933(1)

# 复位
ad5933.reset()

# 测量阻抗
freq = 1000  # 频率
gain = 1  # 增益
range = 2000  # 量程
num_increments = 10  # 段数
num_settling_cycles = 10  # 平稳周期
magnitude, phase = ad5933.measure_impedance(freq, gain, range, num_increments, num_settling_cycles)