Micro-USB

Published on 2020-07-17 in Fluff M0.

The last version is all correct — it has all the pins in the right places, the USB-C socket works well with the pull-down resistors in place, there is a large prototyping area and the staggered pin holes. Not much left to improve. However, if I think about the original goal of being a cheap replacement for the Feather M0 Basic to be left in projects or used for workshop, there is still some room for improvement, so I decided to try one more time.

First of all, black silkscreen with yellow soldermask is uncommon combination (which is a damn shame, it looks much better than white silkscreen, and they use black silkscreen for white soldermask already anyways), so to get the cheesy looks I would need to pay extra for the uncommon color combination. So if I used a decoration that works well with other colors, I could save here.

Second, USB-C cables are expensive, and USB-C ports are usually only on new and expensive devices. If I organize a workshop, I want it to be available for everyone, and not just the rich kids — so I would have to provide USB-C to USB-A cables (expensive). However, the same technique as used for the USB-C socket can be also used for the Micro- USB socket — you won’t get the satisfying click when the plug is inserted, but otherwise it should work the same. And I can ditch the two resistors then!

Third, the prototyping area on the Feather M0 Basic has some additional rails for power — that would be useful and help avoid some cable mess.

So I designed this:

This version is a little bit more obviously Swiss, uses micro-USB socket, and has a prototyping area with power rails and some extra pads in it for squeezing SMD components in there. It also has the LED in a position a little bit more similar to where original Feathers have it, and a second prototyping area where the battery socket normally goes. Otherwise it’s all the same stuff as previously.

The PCBs are ordered and I will be testing the prototypes as soon as they arrive. I will publish the designs if they test fine.