Cobra IO21 PullUp Resistor

I have a Cobra right out of the box. Nothing connected except USB and external power. I can’t get IO21 signal to pullup. No issue with other IO’s.

Are all IO’s tested before shipping? Is IO21 reserved for something not documented?

Thanks -AP

It looks like IO21 is used for EMX / Cobra board detection it has a 10k pulldown so the software knows whether its a lone EMX module or if its mounted to the Cobra…

I should imagine it is documented somewhere…

Cheers Ian

Please check schematics

This is not documented beside schematics but we use this in our libs to detect Cobra vs EMX DevSys if necessary…as a future need

Hi everyone

Does it mean that we should not reuse IO21 for an other purpose? Should we keep it as a GHI reserved pin?

I’ve just received my two EMX modules and start to write my schematic for a custom PCB. This post is therefore very relevant to me.

You can use it

Hi all,

Let me pull this topic on top of the list for a quick question : So as IO21 is pulled down to 10k on the Cobra, does it mean that it is reserved and unsable if the EMX is mounted on the Cobra ?



I believe this means you can use it if you want to, but it WILL be pulled down and you can’t change that.

FYI, PDF moved to