MCP23017 GPIO Expander Demo PCB: Arduino Uno Relay Driver

PCBWay Supports High Precision Advanced PCBs: www.pcbway.com/
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.
Sketch/Schematic: github.com/GadgetReboot/MCP23...
Buy PCBs from PCBWay: www.pcbway.com/project/sharep...
MCP23017 Datasheet: ww1.microchip.com/downloads/e...
ULN2003 Darlington Driver Datasheet: www.st.com/resource/en/datash...
G5V-2 Signal Relay Datasheet: omronfs.omron.com/en_US/ecb/p...
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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Videos are mirrored at LBRY/Odysee: odysee.com/@GadgetReboot:4
#ElectronicsCreators

[@PCBWay]

That's really informative! Good work 👍🎉

[@DrexProjects]

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

[@GadgetReboot]

i’ll be experimenting with latching coil relays in a smaller footprint soon, not sure what I will end up settling on but I’ll keep that in mind!

[@onecircuit-as]

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

[@GadgetReboot]

I am soon also going to be trying to work with those ATtiny devices you sent a while ago, hopefully next month I’ll have some project videos on those.

[@onecircuit-as]

That WAS awhile ago! Sell them to a car manufacturer - they can't get any! 😂

[@GadgetReboot]

yeah I was just starting to pack everything up for the big move and it took this long to feel settled again. I just recently ordered more parts from Mouser including more of those ATtinys and they were scarce but I managed to get a few scraps.
All the ones I would’ve preferred were not available because they were basically close to the same price but might have double the memory so of course those are the ones everyone took first.

[@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.

[@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.

[@GadgetReboot]

I wish I had bought more of the IO chips when I bought the first five because now I want more and they are not that easy to find unless I want to pay a premium and hope they are not fake from the usual low-cost sources. So I think I will be rotating the five chips between different projects thanks to the sockets on the board.

[@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.

[@GadgetReboot]

yeah I will only be switching low-level signals, and I don’t want to blast through any gold.

[@SimpleElectronics]

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

[@GadgetReboot]

there’s always a method to this kind of madness. There will be many more relays getting soldered in the next couple of months.

[@shakerileiwat4341]

Amazing 👍👍👍

[@domoledlight]

good video

[@pileofstuff]

Those expander chips are a very useful beast.
Imagine having 128 GPIO hanging off an ATTINY85!

[@GadgetReboot]

New video idea

[@theonewhowas7709]

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

[@jenniferw8963]

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

[@gathda]

❤️