Random pins HIGH

So I’ve been using Cayenne for a while now and have found it really good. I do have a problem though.
For some reason, pin 4, 10, 11 and 12 are HIGH for no reason. I haven’t set them to HIGH, but they are…
Please help

On these pins communications between Arduino and Ethernet shield

Sounds like @tad.dvor is probably onto it here, but figured I would probably ask what hardware you’re using to make sure that’s the case. There are a number of reserved pins on Arduino, though some of them are only reserved in certain situations. You can find listings of them like this one for Uno/Ethernet Shield R3 online.


Im using arduino uno with W5100 ethernet shield.

Yep, then it looks like he was spot on. The pin numbers were probably a dead giveaway, I just don’t have them memorized yet :slight_smile:

Ok, I guess I’ll just use a Mega

Just to offer another option that might be potentially cheaper/smaller, if you’re out of I/O pins you can use I2C I/O Expander chips to add additional pins to an Arduino/Raspberry Pi project as well.

Oh yeah! Thats a good point.