ledsonMCP23017 example

To be honest, as the circuit we used is just the reference design, it's available online in many places already, and also in the device datasheet. We'll try and add a circuit diagram to the page though in the futre.

Thanks,
Dave

Something to think about is that the MCP23017 is not the most straightforward device to use for someone new to Arduino. Firstly, it's quite a complex device with a lot of options. Also, It really needs clean power, and bypass capacitors are an absolute must, and they must be as close to the power pins as possible. I'd go for at least 10uF in parallel with 0.1uF. Whichever design you use, make sure the reset pin is in a known state.

Datasheet doesn't have an example. http://ww1.microchip.com/downloads/en/DeviceDoc/20001952C.pdf
nor this: https://cdn-shop.adafruit.com/datasheets/mcp23017.pdf

Hi there,

I've added an example circuit to master in the repo so it will be in the next release, it's a circuit diagram based on how I usually assemble this device on bread-board. Please double-check it for me while you're building it out. Especially that the power connections are right etc. I have checked over it before pushing it but even so, please check it again.

https://github.com/davetcc/IoAbstraction/blob/master/examples/ledsOnMCP23017/mcp23017-schematic.png

Like I said before, the MCP23017 is a far more complex device than the PCF8574, it certainly needs a 0.1uF capacitor right next to the power input at the absolute minimum.

Thanks,
Dave

Hi Dave
Thanks for the prompt response. I'm dealing with an existing hardware implementation that uses the mcp23017/mcp23018 and am attempting to revise the software to use your tasking approach. So purchased a stand-alone unit for experimentation and learning.

Big learning curve! Love your work.

This helps a lot. Will test it out and get back.

Jerry