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MCP3421

Arduino

The MCP3421 A/D converter and the Micro:bit

by shedboy71

The MCP3421 ADC can be used for various high accuracy analog-to-digital data conversion applications where ease of use, low power consumption and small footprint are major considerations.The MCP3421 is a single channel low-noise, high accuracy delta-sigma A/D converter with differential inputs and up to 18 bits of resolution in a small SOT-23-6 package.

The on-board precision 2.048V reference voltage enables a differential input range of ±2.048V. The device uses a two-wire I2C™ compatible interface and operates from a single power supply ranging from 2.7V to 5.5V. The MCP3421 ADC performs conversions at rates of 3.75, 15, 60 or 240 samples per second with corresponding resolutions of 18, 16, 14 and 12 bits. The onboard programmable gain amplifier (PGA) provides gain up to 8x. The device has two conversion modes: Continuous mode and One-Shot mode. In One-Shot mode, the device enters a low current standby mode automatically after a conversion, greatly reducing power use.

Features
    • 18-bit resolution
    • Small 6-lead SOT-23 packaging
    • Differential input operation
    • On-board voltage reference with 5 ppm/°C drift
    • On-board PGA, gains of 1, 2, 4, 8
    • Programmable data rate options
      • 3.75 SPS (18 bits)
      • 15 SPS (16 bits)
      • 60 SPS (14 bits)
      • 240 SPS (12 bits)
    • INL 10 ppm of FSR max
    • Low current consumption, 145 µA at 3V
    • One-shot or continuous conversion options
    • Supports I2C™ serial interface

Parts List

Part Link
MCP3421 MCP3421 I2C SOT23-6 delta-sigma ADC Evaluation Board
Connecting cable Free shipping Dupont line 120pcs 20cm male to male + male to female and female to female jumper wire Dupont cablefor Arduino
Micro:bit Micro:bit Development Board

 

Connection

Its an I2C device – I connected the VIN- to Gnd and Vin+ to Pin 6

 

Code

You need to download and install the following library – https://github.com/uChip/MCP342X

This is the default code example

[codesyntax lang=”cpp”]

// Include libraries this sketch will use
#include  <Wire.h>
#include  <MCP342X.h>

// Instantiate objects used in this project
MCP342X myADC;
int outputPin = 6;

void setup() 
{
  Wire.begin();  // join I2C bus
  TWBR = 12;  // 400 kHz (maximum)
  
  Serial.begin(9600); // Open serial connection to send info to the host
  while (!Serial) {}  // wait for Serial comms to become ready
  Serial.println("Starting up");
  Serial.println("Testing device connection...");
  Serial.println(myADC.testConnection() ? "MCP342X connection successful" : "MCP342X connection failed");
    
  myADC.configure( MCP342X_MODE_CONTINUOUS |
                   MCP342X_CHANNEL_1 |
                   MCP342X_SIZE_16BIT |
                   MCP342X_GAIN_1X
                 );

  Serial.println(myADC.getConfigRegShdw(), HEX);
  
}  // End of setup()

void loop() {
  static int16_t  result;
  for(int i=0; i<=255; i++)
  {
    myADC.startConversion();
    analogWrite(outputPin, i);
    myADC.getResult(&result);
    Serial.print(i);
    Serial.print("  ");
    Serial.print(result);
    Serial.print("  ");
    Serial.println(result, HEX);
  }
  
}  // End of loop()

[/codesyntax]

 

link

Datasheet – http://ww1.microchip.com/downloads/en/DeviceDoc/22003e.pdf