Tuesday, August 29, 2017

16mm Split 40%


This is a split 16mm IOTA. It is a single reversible PCB used for both the left and right sides. It is a much smaller version of a Let's Split. It is a split version of the 16mm 1 IOTA.

Pictures comparing it to a Let's Split with PCB plates.

It shares the same matrix pinout as the Let's Split Rev 2 and will run the same firmware. The primary difference (other than switch spacing) is the lack of jumpers. The Half IOTA is setup for Serial communication between the halves. I2C jumpers and pull up resistors are not present. The jumpers for the TRRS jacks are not necessary since the jacks used are surface mount and are wired correctly for each side.

The boards are designed to be assembled using a second PCB as the base. There is no switch plate, PCB mount switches must be used.

M2 spacers and screws. You must install the spacers in the top plate before installing the switches since the screw holes are not accessible with the switches in place.

All of the unused pins are broken out to pads at the top of the boards. The unused connection in the TRRS connector is also broken out to a pad.

The Pro Micro's are in sockets. They must be oriented correctly for each half to work.

The TRRS jack is from Sparkfun. Part PRT-12639, they are $0.95 each. Sparkfun has distributors in many countries.

LCSC has a comparable part PJ-320D-A. The registration pins are much smaller so it needs to be held in place when soldering to keep them straight. They are only $0.0633 each, with a 5 piece minimum.

PCB on github.

The file is small enough for the $2 special at easyeda.com. $2 for 10 PCB and $18 for DHL shipping. $20 for 10 PCB's, enough to build two complete sets and have a spare half.