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Full machine-readable index: https://core-electronics.com.au/llms.txt # Adafruit MCP23017 I2C GPIO Expander Breakout - STEMMA QT / Qwiic **Type:** Product page · **SKU:** ADA5346 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia) **Page:** https://core-electronics.com.au/adafruit-mcp23017-i2c-gpio-expander-breakout-stemma-qt-qwiic.html ([markdown](https://core-electronics.com.au/adafruit-mcp23017-i2c-gpio-expander-breakout-stemma-qt-qwiic.html.md)) We’ve gotten a lot of requests for a MCP23017 breakout and we’ve always sorta been like “ehh why not just use the DIP chip?” but... ## Pricing - **Price:** $11.25 (inc GST) — $10.23 AUD, exc GST - **Quantity discounts:** 10+ $9.92 (exc GST) · 50+ $9.72 (exc GST) ## Availability & dispatch - Available with a lead time — expect dispatch between Aug 31 and Sep 02. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=ADA5346:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/ADA5346:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## Description We’ve gotten a lot of requests for a MCP23017 breakout and we’ve always sorta been like “[ehh why not just use the DIP chip?](https://core-electronics.com.au/mcp23017-i2c-16-input-output-port-expander.html)” but with STEMMA QT Adafruit could see the use case for a plug and play version that comes with all the passives on board. This **Adafruit MCP23017 I2C GPIO Expander Breakout** has 16 GPIO with matching ground pad. Adafruit particularly like the '17 as an expander for it's simple no-nonsense capability. It runs happily from 3V or 5V logic and power. Each GPIO can be an output driving up to 25mA, so LEDs are no problem. Or, each can be an input, with optional pullup. There are two IRQ pins that are configurable for what inputs to keep track of so no I2C bus polling is required. With 3 address pins, you can have up to 8 on a single bus for a total of 8 x 16 = 128 GPIO all on one I2C bus! Adafruit have got solid [Arduino](https://github.com/adafruit/Adafruit-MCP23017-Arduino-Library) and [CircuitPython libraries](https://learn.adafruit.com/using-mcp23008-mcp23017-with-circuitpython) with examples, all ready for this chip. But even if you are using some other platform, the MCP23017 is so classic, you'll likely be able to find example code. Comes with two sticks of header so you can use it in a breadboard, with some soldering. You can also free-wire buttons by connecting one side to the GPIO (set as input with pullup) and the other side to a ground pad. To get you going fast, Adafruit spun up a custom-made PCB in the[ **STEMMA QT** form factor](https://core-electronics.com.au/search?q=stemma%20qt%20sensor), making it easy to interface with. The [STEMMA QT connectors](https://learn.adafruit.com/introducing-adafruit-stemma-qt/what-is-stemma-qt) on either side are compatible with the [SparkFun Qwiic](https://core-electronics.com.au/catalogsearch/result/?q=qwiic) I2C connectors. This allows you to make solderless connections between your development board and the MCP23017 or to chain it with a wide range of other sensors and accessories using a [**compatible cable**](https://core-electronics.com.au/search?q=stemma%20qt%20cable). [QT Cable is not included, but we have a variety in the shop](https://core-electronics.com.au/search?q=stemma+qt+cable). ## Technical Details Product Dimensions: 43.0mm x 18.0mm x 5.0mm / 1.7" x 0.7" x 0.2" ![RoHS 2 2011 65 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2011_65_EU_7356c5574c.svg) ![RoHS 2 2015 863 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2015_863_EU_86773f57f9.svg) ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/i/m/image_12570.jpg)