build-guide.md

Steps

1. Install diodes. Place them over the silk screen markers so you don't cover the pads for the hotswap sockets. This means both sides will be the same and yes, you'll have diodes on the top and bottom of both halves.
2. trim the diode legs but keep them as we'll need them later for the ProMicro pins (into the sockets) and for bracing the switchplate to the middle/PCB layer.
3. Install the reset switch. First tin one of the pads
4. then reflow the tinned pad and solder a leg of the reset switch
5. now you can solder the other legs
6. If you're using an LED on the top, install that now. Do the same trick as the reset switch where you tin one pad, reflow, then solder the other pads. The 144 LEDs/m don't seem to have space to label the pads but on mine, the edge with the arrow is the GND. If you want LEDs on the bottom but not on the top, solder the top bypass in the middle of the WS2812 pad, marked with {L|R}_NO_F_LED.
7. Install the TRRS connector on the top of the PCB
8. If you're NOT using an LED strip on the bottom, solder the bypass marked {L|R}_NO_B_LED. The bypass jumper is on the top of the PCB and when soldered will connect the Do from the top LED to PIN on the TRRS connector that sends the LED data to the other half. This will appear on the SLAVE_LED pin on the slave.
9. (optional, for OLED) solder the jumpers on the top of the PCB. It can be a bit fiddly to get the solder to jump the gap. I've found the best way is to make sure you heat both the pads properly (have the iron in contact for a few seconds) and lift the iron up when you're done. If you drag the iron sideways, the solder doesn't seem to want to jump the gap. If you can't get the solder to jump the gap, like this (don't install the header first, like I did. That was a mistake): ...then use a small piece of diode leg to bridge the gap. I used a longer piece then trimmed it after soldering.
   All four jumpers should be soldered at the end:
   
10. (optional, for OLED) install the I2C resistors
11. (optional, for OLED) install the header. If you only want to run one OLED, I suggest putting it on the left as that ProMicro mounts upside down which lets the OLED mount lower.
12. Install the 11 standoffs. Make sure you use cap screws (allen key head) on the top of the middle layer. This is so you can always tighten them after assembly. A phillips head screwdriver probably won't fit through the hole in the switchplate. (Yep, I forgot two diodes in these photos.)
13. Install the ProMicro sockets. Do not solder the ProMicro directly to the PCB. It's best to sit them in the holes and hold them in with some tape. Then solder one pin and you can remove the tape. Now you can reflow the single soldered pin and make sure the socket is flat and lined up. If you use your finger, don't put it over the pin you're heating, it will get hot.
14. Install 4 MX switches, one in each corner of the switch plate. Mount the switch plate over the PCB/middle layer. When you install the switches, make sure the legs go through the holes and do NOT have the visible solder pads next to them. Here's a view from the bottom that shows why we use those holes; so the pins line up with the pads on the bottom side.
15. Now we need to brace the switchplate to the middle/PCB layer. As this keyboard uses hotswap sockets, we don't want the switch plate to move around when we're changing switches. You can always cut or desolder these later to pull the switchplate off. Drop diode legs through all the switchplate brace holes so they sit on the desk.
16. Solder the tops of the braces and trim the excess
17. Make sure the switches are completely seated and the switchplate is pulled up to the correct height. We're about to attach the switchplate to the PCB/middle layer. Flip over and solder the bottom of the braces and trim the excess.
18. Install the rest of the MX switches, paying attention to install them the correct way. They don't all go the same way.
19. Install the switch hotswap sockets. Again, not all of them are the same orientation so pay attention.
20. Solder all the hotswap sockets
21. Install the Choc switches and solder
22. Install the ProMicro using left over diode legs. Insert them into the sockets, making sure they go all the way in. Then solder them to the ProMicro and trim the excess.
23. Install the base plate
24. (optional, for OLED) Install the OLED screen
25. Repeat for the other half
26. flash firmware to both halves

Option: floating middle PCB

If you want to, you can use a 4.5mm drill bit to drill out the M2 mounting holes on the PCB (middle layer of sandwich). This means your standoffs are attached between the base and switch plate, passing right through the middle layer.

There are M2 mounting holes to support the Choc row of switches. If you cannot find standoffs the correct height, there is another option to support these switches. There are two small plated through holes; one at either end of the row of Choc switches. Solder up the holes in the base layer and solder a diode leg into the hole on the PCB/middle layer. The diode leg will then rest on the solder on the base plate and provide support.

Option: join underglow LEDs between halves

QMK is meant to be able to directly control the backlight LEDs on the slave side of the keyboard. At the time of writing, I couldn't get this to work. So if you want to run underglow on both sides, or if you want all your underglow LEDs in one long chain, you can link them together.

To do this, one the master side, you need to use a piece of wire to connect the Do (output) from the LED strip to the SLAVE_LED plate through hole connector just below the ProMicro.

Then, on the slave, you connect the SLAVE_LED pin to the Din (input) of your LED strip. If you want to also run the top LED on the slave, you'll have to wire that up yourself.