I2C on the Plumduino

Plumduino setup, hardware, basic programming. User to user support.
TelegramSam
Posts: 4
Joined: Thu Aug 18, 2016 5:02 am

I2C on the Plumduino

Postby TelegramSam » Mon Dec 26, 2016 7:26 pm

Santa delivered some goodies, and I'm trying to get an I2C device working on the plumduino. I was able to get it working on just the board itself, but when I plug the plumduino into the expansion board, it stops working.

I have added female headers to the expansion board so that I can easily tap into those pins.

Can you shine some light on this for me, and tell me what I'm not understanding?

Kevin
Posts: 127
Joined: Tue Jul 28, 2015 12:56 am

Re: I2C on the Plumduino

Postby Kevin » Thu Dec 29, 2016 3:33 am

Hello Sam,

Arduino uses A4 and A5 for I2C, and we use these analog pins to connect to the pair of sliders on the expansion board. I think it's likely I2C will still work if you set the sliders just right.

I'm sure you're familiar, but I2C requires a weak pull-up on each line. I don't have the schematic in front of me but I'm rather certain we don't populate these. You can probably however use the slider position to approximate a pull-up. My guess off hand is to set both sliders near one end, but not all the way to the end. Not sure which end off hand but try both and set them both to the same amount. You may get lucky and find the correct location.

If you do happen to have access to a scope, you can see both signals on the test points SLIDE1 and SLIDE2.

I really wish the chip had a few more pins but unfortunately that wasn't how they designed it. :(

Hope that helps!

Thanks!
-Kevin


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