Confused by pins

I am putting final touches on the PCB for my weather station, and when double checking everything, I suddenly got confused by what some pins was used for, then got even more confused when I wanted to double check it.

In the image for the April board ( it seems to have the pin next to the 3V3 pin is connected to GND. But when measuring on my april board I got in front of me, it is number 4 from the left instead. The one connected to GND on the picture is connected to Dtst on the april board I got in front of me. And that is also how my old board seems to be made, which does work.

Anyone want to double check my device I designed in Eagle? That would be a stupid error to have in.

Hi MikeyDK,
That’s some serious attention to detail! The answer is that the Detect pin and the GND pin are mostly interchangeable, though manufacturers never seem to agree on which is which. If this sounds a bit weird it might be helpful to understand how it works. The detect pin and GND pin both contact the GND pin on the Imp card. Thus when Imp is inserted the Detect pin is connect to GND through the Imp’s GND pad.

When we changed socket providers between Rev 1 (pictured on the website) and Rev 3 (the one you have in front of you) we also swapped those pins.

In general we recommend connecting both the GND pin and the Detect pin to GND as that doubles the number of GND contacts for the Imp!

Let me know if anything is unclear.

Awesome, makes sense why both worked then. :wink:

This is how it ended up looking.

A bit harder to see on the board with everything else on.

This new version of my PCB also went from 85.5mm to 78mm in lenght, those omron relays are about half the size of the ones I used before. :slight_smile:

Lovely curved traces… not seen that apart from for RF traces before!

Yeah, I know they don’t make any difference, I just like the look of them. :wink:

Both connected to GND, and a bit of via stitching too. Should be sufficient. :wink: