Monday, July 17, 2017

Conjoined Let's Split

A Let's Split stuck to itself

I did not have separate cases for the two halves so I put both in one of the plates I made for a Planck. The switch spacing for a Planck is 19mm and the Let's Split is 19.05mm. The difference is small but it shows. There is a slight bowing of the plates. Being only 6 columns wide reduces the total offset. If it were a single 12 column PCB the offset would be 0.55mm from end to end. As it is there is a 0.25mm offset for each side. Socketed Outemu teal switches were used so this can be disassembled and put in a new case later.

The TRRS cable is a bit short for normal split use. They are a good length for a permanent umbilical. Sort of looks like crab eyes.

I flash my Pro Micro's with the Atmel DFU bootloader. With the default fuses the JTAG port is enabled by default and needs to be disabled to use Port F. Adding the following code to matrix.c  in the matrix_init function will disable JTAG.

 // To use PORTF disable JTAG with writing JTD bit twice within four cycles.
MCUCR |= (1<<JTD);
MCUCR |= (1<<JTD);

Split PCB case

 Crab eyes sticking out the top.

 The Pro Micro's stick out from the front.

 12mm spacers. I used a low profile socket on one side and a full height on the other.

 6 inch TRRS cable.

 A notched ground between the two PCBs for the center post.

 Small notches on the top and bottom of each PCB.

Jumper to fix a scratched trace.