I have now had a lesson in patience. My PCBs arrived from OSH Park yesterday. They are of top quality. However, I should have checked over my design a few times before submission.
On the face of it, they look fine and again, I draw your attention to the very high quality that OSHPark attain. But if you take a look at this close-up image, you may spot the problems.
I have indicated with a red circle part of the issue. For some reason, Eagle didn’t alert me to the overlapping contacts here. Perhaps it did and I didn’t see it for what it was. A problem! Also, at the time I designed this PCB, I hadn’t found the ZIF Socket in the libraries. I thought it would be OK to use any 40-pin DIP pattern. Of course, what I failed to take in to account is that ZIF Sockets are wider than your average 40 pin DIPĀ device and I hadn’t given enough room for it.
I have tried to salvage something from this by making an adapter and trying to work out how to outboard the crystal oscillator but I think I’m going to chalk it up to experience and order my new version at some stage.
For this version, I took my time and found a ZIF Socket pattern. I’ve laid it out in a completely different configuration and spent some time to label things properly on the silk screen. Before I order any, I will check it again to make absolutely sure I have not made any mistakes.
A long time ago, when I was at school, an engineering teacher told me ‘Measure thrice, check twice, cut once only’. I should have put that into practice!