用Arduino玩ESP32（06）：CD74HC4067使用一

  CD74HC4067 作用是选通一路对十六路模拟信号，就像一个单刀多掷开关，根据芯片上 S0-S3 四个不同管脚的组合，让SIG管脚和C0-C15导通（每次只能连接一个），它适用于数字和模拟信号，可以只用5针最多连接16传感器系统，也可以用它来管理多个设备。

//测量换算每个Pin的电压
int s0 = 34;
int s1 = 35;
int s2 = 32;
int s3 = 33;
int SIG_pin = 25;
void setup() {
  // put your setup code here, to run once:
  pinMode(s0, OUTPUT);
  pinMode(s1, OUTPUT);
  pinMode(s2, OUTPUT);
  pinMode(s3, OUTPUT);

  digitalWrite(s0, LOW);
  digitalWrite(s1, LOW);
  digitalWrite(s2, LOW);
  digitalWrite(s3, LOW);
  Serial.begin(115200);

}

void loop() {
  // put your main code here, to run repeatedly:
  int v;
  for (int i = 0; i < 16; i ++)
  {
    Serial.print("Value at channel ");
    Serial.print(i);
    Serial.print(" is : ");
    v = readMux(i);
    Serial.println(v * 5.0 / 4096);
  }
  Serial.println(" ");
  delay(3000);

}
int readMux(int channel)
{
  int controlPin[] = {s0, s1, s2, s3};

  int muxChannel[16][4] =
  {
    {0, 0, 0, 0}, //channel 0
    {1, 0, 0, 0}, //channel 1
    {0, 1, 0, 0}, //channel 2
    {1, 1, 0, 0}, //channel 3
    {0, 0, 1, 0}, //channel 4
    {1, 0, 1, 0}, //channel 5
    {0, 1, 1, 0}, //channel 6
    {1, 1, 1, 0}, //channel 7
    {0, 0, 0, 1}, //channel 8
    {1, 0, 0, 1}, //channel 9
    {0, 1, 0, 1}, //channel 10
    {1, 1, 0, 1}, //channel 11
    {0, 0, 1, 1}, //channel 12
    {1, 0, 1, 1}, //channel 13
    {0, 1, 1, 1}, //channel 14
    {1, 1, 1, 1} //channel 15
  };

  //loop through the 4 sig
  for (int i = 0; i < 4; i ++)
  {
    digitalWrite(controlPin[i], muxChannel[channel][i]);
  }

  //read the value at the SIG pin
  int val = analogRead(SIG_pin);

  //return the value
  return val;
}