12 Bit I2C ADC breakout with voltage reference

A simple to use, yet versatile ADC breakout with voltage reference. (Vref-4.096v, I2C address-A5)

Compatible with breadboards and the Seeed grove connector this unit is easy to use and interface! Unit is based on the proven MCP3221 and MCP1541 pair and is quite compact, it provides a good mix of speed vs precision especially for the price! capable of 28.8Ksps when operating in I2C Fast mode.

Basic Usage

Using the breakout is very easy and the code should be self explanitory! Hook up the breakout board via I2C, add VIN and common ground with both the Arduino(or what ever you are interfacign with) and what ever you will be reading! VCC takes a wide range from 2.7v to 5.5v although above 4.1v the Vref takes over and provides a stable 4.096v as VIN (NOTE: SDA and SCL will be at VCC levels, this is good and bad; Feed VCC with 3.3v and you can hook right up to a raspi or Arduino, feed with 5v and you can only hook up to Arduino)

Various Info

• ~1mV/Step resolution at VIN > Vref
• Wide range of VIN inputs (2.7 to 5.5V)
• Easy to use 12bit ADC

Example code

    #include 
    #define ADDRESS 0x4D // MCP3221-A5 address (There are other addresses available)

    float vRef = 4107; //vRef reading in mV - Check This WIth DMM
    float stepSize = vRef/4096; //Each step = our vRef/ number of steps in 12bit

    void setup(){
      Wire.begin(); //Initialize I2C comms
      Serial.begin(9600); //Initialize Serial comms
    }

    void loop(){
      byte adc_MSB;
      byte adc_LSB;
      int adcRaw;
      float miliVolts;

       Wire.requestFrom(ADDRESS, 2);        //requests 2 bytes
       while(Wire.available() < 2);         //while two bytes to receive

       adc_MSB = Wire.read();           
       adc_LSB= Wire.read();
       adcRaw = (adc_MSB * 256) + adc_LSB;
       miliVolts = adcRaw * stepSize;
       Serial.print("ADC RAW: ");
       Serial.println(adcRaw);
       Serial.print("Voltage: ");
       Serial.println(miliVolts/1000);
       Serial.print("mV/Step      : ");
       Serial.println(stepSize,4);
       delay(1000);
    }