Named after a small North American bird, Junco is a 60% Raspberry Pi Pico powered split keyboard boasting a 4x6 layout with an aggressive columnar stagger, 2-4 rotary encoders, and per-key RGB lighting.
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Junco is inspired by the excellent crkbd, Iris, Kimiko, Sofle, and Ferris keyboards. Massive thanks to @JellyTitan for the wiring overhaul.
In my search for an ergonomic split keyboard, I came across several great keyboards, but I craved a combination of features and ideas from several with my own flavor. Iris' aesthetics, Kimiko's stagger and layout, elements of Ferris' philosophy.
I also wanted to use Raspberry Pi Picos for the controller as it has many advantages over the ProMicro that is normally used in custom keyboards. At the time, Pico powered keyboards were not yet really a thing and weren't yet supported by the main QMK branch. Thus, I created my own keyboard.
The Junco was designed around a set of goals, similar in vain to the Ferris.
Goals:
Non-goals:
Being my first venture into keyboard design... Junco unfortunately suffers from a few "quirks" at the moment that may or may not bother you:
Where "56-58" is the count, 58 is needed with 2 rotary encoders. subtract from 58 every additional encoder (4 encoders 56, with 3 encoders 57).
Name | Count | Remarks | Potential Storefront |
---|---|---|---|
PCB | 2 (1 left and 1 right) | PCBs can be ordered from manufacturers such as JLCPCB and LCSC | |
MX Hot-swap Sockets | 56-58 | ||
Diodes | 62 | Surface mount SOD-123 1N4148, or through-hole 1N4148 diode. These are both common and inexpensive, any one should do. Through hole is usually easier to solder. | SMD: AliExpress JLCPCB Part#: C2972760 Through-hole: AliExpress |
Raspberry Pi Picos | 2 | PCB is specifically designed with the official Pico and YD-2040 type clone in mind, however several other clone types should be compatible (Waveshare, WeAct, EstarDyn, Tenstar). Also, the case is currently designed assuming the Pico is soldered with headers, but surface mounting the Pico is supported on the PCB. | AliExpress, YD-2040 |
TRRS Jacks | 2 | PJ-320A | AliExpress |
TRRS Cable (3.5mm "Headphone" Cable) | 1 | TRRS (4 pole) is currently required, not TRS (3 pole) | |
MX Style Switches | 56-58 | ||
Key Caps | 56-58 | ||
Rotary Encoders and Caps | 2-4 | EC-11 Rotary Encoder | AliExpress |
M3 6mm or 6mm+ Screws and Nuts | 8 | ||
Case | 1 Left Set, 1 Right Set | Case files are located in the case folder. | |
Micro USB Cable or USB-C Cable | 1 | USB cable for connecting the keyboard to your computer, dependent on what the Pico you chose uses. |
These parts are necessary for the RGB lighting.
Name | Count | Remarks | Potential Storefront |
---|---|---|---|
74AHCT1G125 Voltage Level Shifter/ Bus Buffer | 2 | SOT23-5 Footprint Required for LEDs to work properly, Pico runs at 3.3V while the LEDs will require 5V |
AliExpress JLCPCB Part# C7484 |
RGB SMD LEDs (Prefer SK6803MINI-E) | 74 | The 3MA SK6803MINI-E is highly recommended over the more traditional 12MA SK6812MINI-E due to its smaller current draw, allowing the LEDs to be very bright at manageable wattage. | AliExpress JLCPCB Part# C5184589 |
The PCB is not reversible, there is a dedicated right and left half in the KiCad PCB files. Almost all of the soldering will occur on the backside of the PCB.
Solder the diodes as you see in the photo. SMD diodes are soldered on the back of the board. Through-hole diodes are inserted on the back of the board, and soldered on the front.
[!WARNING] Note that the diodes have polarity, ensure the line on the diode matches the silkscreen.
All LEDs must be soldered to the PCB for RGB to work properly, even if you will not be using backlight or will be using an encoder that covers an LED. (They are wired in serial).
First solder the level shifter. It's tiny & squirrley - drag soldering" is a good method. See photo:
All LEDs will be soldered facing down into the board. The LEDS for per-key RGB will be soldered on the back of the board, while the LED's for the underglow will be soldered on the front of the board.
[!WARNING] Note the LED orientation is very important. One of the pads on each LED (the ground pin) will be misshapen relative to the others, this pad should connect to the PCB pad that is marked by the L shape on the silkscreen. For a sanity check, a corner of the LED's front-side will also be "cut", this corner must also line up with the L shape on the silkscreen.
Blue is LEDs that will be installed on the underside of the board, facing the front-side of the PCB for the per-key lighting. Red will be installed on the front of the board for the underglow:
Per Key leds soldered on the backside, while underglow LEDs ssoldered on the opposite side:
Ground pin orientation:
After you finish the next step of soldering the Pico to the PCB, recommend plugging the keyboard in and flashing QMK to ensure the LEDs are lighting up. If there are any issues, check the troubleshooting section.
If you are soldering the Pico surface mount style, go ahead with soldering it to the backside of the PCB and you can skip to the next section.
If you are soldering the Pico using headers, first solder the Pico to the headers and then the header/Pico to the PCB.
Ensure that you are soldering the Pico/Header onto the backside of the PCB.
The best way to go about this method is to rest the shorter end of the headers in the through-holes of the PCB on a flat surface and place the Pico on top, through the longer end of the header. This will stabilize the headers somewhat and ensure proper spacing. Solder the Pico to the 2 header pins on the both the "top" and "bottom" of the Pico to hold it in place. Proceed to solder the Pico to the rest of the header's pins.
After the Pico is soldered to the header, flip the PCB over and solder the sticking-out header pins to the PCB. Start with the 2 "top" and 2 "bottom" header pins to hold it in place, being sure to minimize the space between the header's plastic and the PCB. Proceed to solder the PCB to the rest of the header's pins.
The end result will look like this:
Backside of PCB:
Front-side of PCB:
Place hot-swap sockets on the backside of the PCB and solder. See photo:
The process for soldering the TRRS jack and the process for the rotary encoders are very similar.
On the backside of the PCB, place the TRRS jack. On the front-side of the PCB, bend the pins of the TRRS jack to "latch" onto the PCB and solder.
Backside PCB:
Front-side PCB:
On the front-side of the PCB, place the rotary encoder(s). On the backside of the PCB, bend the pins of the encoder to "latch" onto the PCB and solder.
Front-side PCB:
Backside PCB:
At the moment, the case files included in the case directory support 3D printing of a case assuming PCB mounted switches (since the 3mm switch plate is resting on the PCB). Since I do not own or have easy access to a 3D printer, the case was designed to be easy to print with 3rd party printing services in-mind such as Treatstock.
Raw files are provided for designing your own case if you see fit. Further work on the case may occur in the future to properly suspend the switch plate. PRs are welcome.
The case is comprised of 4 parts, 8 M3 screws, and 8 M3 nuts.
To have a functional case you need the Bottom Left and Bottom Right along with a Left Switch Plate and a Right Switch Plate. 4 M3 screws and their nuts will hold the switch plate and bottom together for each side of the split. Recommend printing the bottom in white at 40% infill so the underglow LEDs can bleed through.
The naming schemes "- 2 Rotary" and "- 4 Rotary" are products of the raw files used to model the case.
The switch plates named "- 2 Rotary" assume 1 rotary encoder will be used on that side of the split. One by they thumb keys.
The switch plates named "- 4 Rotary" assume 2 rotary encoders will be used on that side of the split. One by the thumb keys and one in the far bottom corner
If you would like to have 3 rotary encoders rather than 2 total or 4 total you would use both variants. The side that will have 2 rotary encoders will use the "- 4 Rotary", while the other side with 1 rotary encoder will use the "- 2 Rotary".
As mentioned in design quirks, there are some problems with making the switch plate flush with the PCB. After you get it flush, you can completely assemble your keyboard! Assembly goes in the reverse of the following:
-- Keycaps --
-- Switches --
-- Case Switch Plate -- (screw + nut connect the plate with the bottom)
-- PCB --
-- Case Bottom --
Junco is powered by the QMK firmware, see the build environment setup. Brand new to QMK? Start with the Complete Newbs Guide.
For users wanting something a little more fun, check out my keymap folder here and my keymap here.
Flashing instructions can be found here.
Congratulations and enjoy your split keyboard!
Try the following until problem solved:
Go through the LED electrical order (pictured below) until you reach the problem LED. That LED or the one previous to it has a problem.
LED Electrical Order (1-8 are underglow):
Right side is identical but mirrored.
Try the following until problem solved:
In this case, there is most likely a problem with the PCB's connection to the Pico. Note that the bottom row of keys is staggered by 2, so the the corresponding matrix column is shifted.
Rows:
Cols:
The right side is identical but mirrored.
Try the following until problem solved:
Note that the bottom row of keys is staggered by 2, so the the corresponding matrix column is shifted. See the photo in the above section.
If it's not a row or column of keys, than there is a bad connection between your switch and PCB.
Try the following until problem solved: