Necromancer's notes

They say on hackaday.com they’re running out of fails for their weekly fail series. So I decided to help them out a little bit 😉
Anyway, a few weeks ago I needed a few usb-to-gpio modules to drive switch some basic stuff on and off from an MK802 dongle. Usually I take an attiny2313 and etch a board for this purpose, but this time I was short on free time to do it myself.
The schematics are well-tested a long time ago. vusb powered firmware based on antares and lunartool applet for the host side are also ready and fully debugged. What could possibly go wrong in such a damn simple project?

However this time boards (already tested multiple times when etched at home) were a failure. Mostly because I was in a terrible hurry to reroute them, replace 2.54 pins with screw terminals, add mounting holes and send them to the fab…

Here are some more photos.

And a list of fails, if you haven’t guessed yet:

• SCK/MISO/MOSI on the silkscreen are way off the real SCK/MISO/MOSI
• mini-usb slot is positioned in a way no cable would fit it. Had to give each board a cut to fix that.
• I screwed up making the 14-pin screw terminal footprint: the drill holes were too small, so I ended up with the hackery shown above.

Apart from that – the design was fully operational. If somebody wants the firmware sources for that – leave it in the comments, and I’ll put it up.

Note to self: Never trace PCBs while in a hurry.