{"product_id":"adafruit-mcp3421-18-bit-adc-stemma-qt-qwiic","title":"Adafruit MCP3421 18-Bit ADC","description":"\u003cp\u003eThe \u003cstrong\u003eAdafruit MCP3421 18-Bit ADC\u003c\/strong\u003e is a simple, inexpensive, and easy to use 18-bit, 240 SPS, single-channel ADC with an I2C interface that can run up to 3.4MHz clock rate. A perfect component whenever you need an ADC that has differential inputs, adjustable gain, and a built in precision\/low-drift reference voltage.\u003c\/p\u003e\n\u003cp\u003eOne of the trade-offs with getting 18-bit precision is that the ADC is not going to be very fast: you can configure the chip to do a faster 12-bit conversion at 240 SPS, but at 18-bits it slows down to 3.5 SPS. That's because the way a\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/en.wikipedia.org\/wiki\/Delta-sigma_modulation\"\u003esigma-delta ADC\u003c\/a\u003e works, it 'guesses' the analog voltage and uses a comparator to determine whether the input is higher or lower. Each 'guess' takes an extra step, and thus halves the throughput, so 12-bit is 240 SPS, and 14-bit is 1\/4 (2-bit) slower, 60 SPS. Ditto 16-bit is 1\/4 slower, 15 SPS, and finally 18-bit is 3.75 SPS.\u003c\/p\u003e\n\u003cp\u003eThe MCP3421 is already set up for differential inputs, which means that you can read positive or negative differences between the two inputs,\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eas long as both signals are between 0 and 2.048V\u003c\/strong\u003e. This means its not going to be great for reading stuff like potentiometers, where you have a single-end reading referenced to ground, and you want to read the full range from 0 to Vcc. It is great, however, for reading sensors like strain gauges, pressure sensors, or thermocouples.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/github.com\/adafruit\/Adafruit_MCP3421\"\u003eAdafruit have a ready to go Arduino library that makes usage simple\u003c\/a\u003e: select the sample rate \/ precision you want and one-shot or continuous mode. Then read values over I2C! This sensor has a fixed address, so\u003cspan\u003e \u003c\/span\u003e\u003ca href=\"https:\/\/learn.adafruit.com\/adafruit-tca9548a-1-to-8-i2c-multiplexer-breakout\"\u003eyou may want to use a multiplexor\u003c\/a\u003e\u003cspan\u003e \u003c\/span\u003eif you want to connect multiple MCP3421's on a single I2C bus.\u003c\/p\u003e\n\u003cp\u003eTo get you going fast, we spun up a custom-made PCB in the \u003ca href=\"https:\/\/www.adafruit.com\/?q=stemma%20qt%20sensor\" title=\"STEMMA QT form factor\"\u003e\u003cstrong\u003eSTEMMA QT\u003c\/strong\u003e form factor\u003c\/a\u003e, making it easy to interface with. The \u003ca href=\"https:\/\/learn.adafruit.com\/introducing-adafruit-stemma-qt\/what-is-stemma-qt\"\u003eSTEMMA QT connectors\u003c\/a\u003e on either side are compatible with the \u003ca href=\"https:\/\/www.sparkfun.com\/qwiic\"\u003eSparkFun Qwiic\u003c\/a\u003e I2C connectors. This allows you to make solderless connections between your development board and the MCP or to chain it with a wide range of other sensors and accessories using a \u003ca href=\"https:\/\/shop.pimoroni.com\/products\/jst-sh-cable-qwiic-stemma-qt-compatible\" target=\"_blank\"\u003e\u003cstrong\u003ecompatible cable\u003c\/strong\u003e\u003c\/a\u003e.\u003c\/p\u003e\n\u003cp\u003e\u003ca href=\"https:\/\/shop.pimoroni.com\/products\/jst-sh-cable-qwiic-stemma-qt-compatible\" target=\"_blank\"\u003e\u003cstrong\u003eQT Cable is not included\u003c\/strong\u003e, but we have a variety in the shop.\u003c\/a\u003e\u003c\/p\u003e\n\u003cp\u003eComes with a bit of 0.1\" standard header in case you want to use it with a breadboard or perfboard. Four mounting holes for easy attachment.\u003c\/p\u003e","brand":"Adafruit","offers":[{"title":"Default Title","offer_id":41365464318035,"sku":"ADA5870","price":5.95,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0174\/1800\/files\/5870-00.jpg?v=1707236566","url":"https:\/\/shop.pimoroni.com\/en-eu\/products\/adafruit-mcp3421-18-bit-adc-stemma-qt-qwiic","provider":"Pimoroni Ltd","version":"1.0","type":"link"}