I have built two custom Ardunio Micro's. One works perfectly, while the other will not connect via USB. After much testing, I have figured out that it seems to be a poorly routed PCB on my part (I used the auto-router). I think there is a crossed connection somewhere, but after poking at the board with a multi-meter for an hour, I cannot seem to find one.
The schematic for each board is practically identical, with no changes to the layout of the processor. Just to make sure that one of the processors isn't bad, I switched them. The same board still works fine, while the bad board will not work. So I know it is something with the PCB.
When I plug the bad Arduino in, nothing happens. The computer does not even say that there is USB device failure, or one plugged in at all. The other is recognized just fine.
I have checked resistance between the D+ and D- pins of the USB port and the pins on the processor, and there is resistance between them with no crossed connection between each other.
I do not understand USB communication enough to try and figure out what is wrong with my second board in compared to my first. Any thoughts? I would like to try to nail down the issue before I redesign the board and hope it works.