MCP23017 GPIO Expander Demo PCB: Arduino Uno Relay Driver

Here's how to get the MCP23017 GPIO expander up and running over I2C with Arduino.
This project shows how to get the expander configured with the Adafruit library, and how to access the 16 GPIO for read and write access.

The project can be made on a breadboard, but this pcb is set up to control 8 relays with status indicator LEDs, read in 4 buttons, and the remaining 4 GPIO are broken out on headers for misc use.

0:00 Intro
0:13 MCP23017 overview
2:41 Schematic review
6:01 Sketch review and various pcb demos
9:20 Summary

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#ElectronicsCreators

[DrexProjects]

Great job. I have a shit ton more of those relays if you want more.

[PCBWay]

That's really informative! Good work 👍🎉

[onecircuit-as]

Excellent video and what a useful board to have, such versatility. 👍😀

[UReasonIt]

Thanks. I have sent for five to be made with my last PCB order. I have this io chip on an stm8 board I made a while back for something and they work quite well. I need to get the relays or make an adaptor-bodge for others I have already.

[andymouse]

What a great board and stuff you had lying about, I can see this being very useful to model makers and the like for simple switching...cheers.

[TheEmbeddedHobbyist]

A word of warning, if you drive 2A through the contract it may not work reliably at very low current after. When switching on very low currents the contracts need very good wetting to do this. This ability to achieve good wetting will be removed with the first current spike on the contracts. So if you want to switch audio don't switch power with the relay before hand.

[SimpleElectronics]

This madman soldered 40$ of relays onto a board just to explain an IO expander!! Great video though!

[pileofstuff]

Those expander chips are a very useful beast.

Imagine having 128 GPIO hanging off an ATTINY85!

[jenniferw]

check out the SIP-1A05 reed relays if you haven't yet. great for audio. You can't hear them click unless you put your ear up to it and then it's very subtle.

[uksuperrascal]

See your odyssey channel comments for this video

[theonewhowas]

why didnt you include the build materials in the description.. i really want to build this

[michaelunrath]

ist es evtl möglich damit 5 Volt bipolare Micro Strepper zu betreiben