Sketch review - USB connector and mounting holes


#21

Assuming this footprint works, this has been a useful exercise in that we should end up with a verified Fritzing friendly microb USB connector which we didn’t have before. Try this one. Note it has a line to indicate where the board edge should be. If positioned correctly at the edge of the board the text on the silkscreen will be truncated as being off board.

micro-USB-connector-MK5P.fzpz (10.6 KB)

Peter


#22

Thanks a lot again, Peter!
I think I have the final design then! :smiley: Time to print and see if everything fits!

Edit: after checking the etching files, I think the mounting holes for the ZS-042 are not added. Should I add holes for this manually?
Edit 2: I checked the drill file with a Gerber viewer, also the mounting holes for the ZS-042 are there. So I can continue to check PCB with the actual parts.

Watchwinder_shield_20190404.fzz (108.8 KB)


#23

The mounting holes are showing correctly in both Fritzing and the gerber output for me. I notice if you were really doing USB you probably need a keepout area between the pins and the 4 square pads on the connector to keep the fill out of there but for power it doesn’t matter. Otherwise looks fine.

Peter


#24

I saw indeed, the holes worked out just fine :slight_smile:

The usb will be used for usb-purposes; there will be a cable from the usb header pins to the Arduino miniUSB, to feed it with power but also enable me to still program it. Why and how should I design the keepout area for the pads then? In the current drawing the four mounting pads are already separatared, right?


#25

Most USB connectors I have seen (this particular footprint did not) indicate no copper or traces near the USB signal pins presumably for signal integrity reasons (perhaps only on USB3). That may or may not affect you. I don’'t know how you specify a keepout area on fills, perhaps one of our pcb folks will chime in.

Peter


#26

I understand what you mean. I double-checked the PCB design rules for USB 3.0 and USB 2.0. The former has quite strict rules about trace width, distance, length matching, etc. USB 2.0 is less fussy about this, the only advice I found is to keep the data traces relatively close and parallel, and not to use over 4" of trace length.
I also noticed that almost all USB 2.0 boards have no copper fill around the signal lines. I removed those from my sketch as well now.

The usb connectors will arrive in a week or so, then I can verify this last but crucial part of the board before ordering. Looking forward to receiving my very first PCB!