Table of Contents

Mcp3428 - Analog to Digital Converter (I2C)

The library implements the Microchip MCP3428 16 bit A/D converter with I2C interface. It has hardware configurable I2C address and software configurable resolution and gain. Can work in continuous and on-demand conversion modes.

Documentation

"The MCP3426, MCP3427 and MCP3428 devices (MCP3426/7/8) are the low noise and high accuracy 16 Bit Delta-Sigma Analog-to-Digital (ΔΣ A/D) Converter family members of the MCP342X series from Microchip Technology Inc. These devices can convert analog inputs to digital codes with up to 16 bits of resolution." - Datasheet

The 3 devices differ only in addressing capability and channel number. The library implements all of them.

Board

MCU Breadboard diagram

Usage

Simple example for measuring LED forward voltage using the MCP3428 ADC and a MCU.

// I2C addres based on pin configuration
var addr = Mcp3428.AddressFromPins(PinState.Low, PinState.Low);
var options = new I2cConnectionSettings(1, addr);

using (var dev = new UnixI2cDevice(options))
using (var adc = new Mcp3428(dev, ModeEnum.OneShot, ResolutionEnum.Bit16, GainEnum.X1))
{
    var ch1 = adc.ReadChannel(0);

    Debug.WriteLine($"LED forward voltage value: {ch1} V");
}

On the MCP3428 you can select 8 different I2C addresses that the device answers on. It's done by connecting two pins, Adr0 and Adr1 to supply voltage or ground or leaving then floating. The library has a helper method to choose the address based on pin states.

With this instantiating the device and reading the first channel is done like this:

var options = new I2cConnectionSettings(1,
    Mcp3428.AddressFromPins(PinState.Low, PinState.Floating));
using (var dev = new UnixI2cDevice(options))
using (var adc = new Mcp3428(dev)) // Default settings
{
    var ch1 = adc.ReadChannel(0);

    Debug.WriteLine($"ADC Channel value: {ch1} V");
}

The library provides an async API as reading with 16 bit resolution can take up to 60-80ms. It's in a separate class called Mcp3428Async.

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