Monday, September 18, 2017

Green Pro Micro

Beware the Green Pro Micro

I found these green Pro Micro's on Aliexpress. There are several sellers. Search for the part number BTE17-05. They have the same pinout as the regular blue Pro Micro's but the power circuitry is very different. For most uses it won't matter, but if you are building a split keyboard that relies on detecting voltage on the VBUS pin on the ATmega32U4 it will not function properly with the green Pro Micro. VBUS is connected directly to VCC so it always receives power. On a normal Pro Micro the slave half does not receive power on the VBUS pin and that is how it knows it is the slave. There are workarounds, by permanently assigning the left/right side as master. But it removes the convenience of swapping sides or using a side individually.

Otherwise, the build quality of the PCB is much higher than typical cheap blue Pro Micros. It was also only $2.75 each (plus shipping). At that price I would buy more. They work fine in a Gherkin and are the same green color. However, they increased the price to $3.40 each, which is about the same as the blue ones.

These are now showing on on eBay.

Side by side with a regular Pro Micro. There is no jumper J1. It is already wired as if J1 were connected.

 The bottoms of both are flat with no components sticking out.

The schematic provided by the seller. You can see the power section is much simpler than that of the regular Pro Micro.