This is a buildguide for cocot38mini.
cocot38mini is designed as a more compact version of cocot series, with column-staggered 38 keys, 25mm trackbvall and 3D printed case. To begin with, please make sure you read this buildguide carefully and you have everything you need before you start to asseble.
| Parts | No. | Notes |
|---|---|---|
| PCB | 1 | |
| Sensor PCB | 1 | |
| Sensor (PMW3360) | 1 | |
| PGA2040 | 1 | |
| Rubber Feet | 4 | |
| Zirconia Balls (2mm) | 3 |
| Parts | No. | Notes |
|---|---|---|
| 3D Printed Case (Top+Bottom) | 1 | You can download 3d data to order 3d printing service by yourself |
| Keyswitch | 37 or 38 | MX |
| Keycap | 37 or 38 | MX |
| Rotary Encoder + Knob | 1 | Optional |
| Spring Pin Header or Pin Header (H2.5mm) | More than 42 pins are necessary | |
| 25mm Trackball | 1 | |
| USB-Type C Cable | 1 |
First, please make sure that you have all the parts listed above. If the PCB comes with tabs, break off the tabs and lightly file the cut surfaces.
Solder spring pin headers (or pin headers) to the PGA2040. In this buildguide spring pin headers are used as example, but you can follow the most steps when you use pin headers.
Cut spring pin headers with a cutter knife and insert them into the bottom side of the PCB as shown in the picture below. The picture shows 2x8pins and 3x6pins as example. Please make sure you insert them in the correct location.
Once you insert spring pin headers to the PCB, insert PGA2040 onto it. Pay close attention to the orientation of the PGA2040.
Check that the spring pin headers and PGA2040 are not floating, and solder for 34 pins on the PGA2040 side. 
After soldering the spring pin headers, plug the PGA2040 into the PCB and write the firmware.
- Press the RESET button (SW39) while holding down the BOOT button (SW40) on the bottom side to enter boot loader mode.
- The firmware is written by dragging and dropping the .uf2 file into the drive named RPI-RP2.
Keymap is editable from vial.
You can confirm that trackball and LEDs are working correctly with this firmware. You can confirm the trackball move after you assemble the following steps.
The default firmware enables "Auto Mouse Layer", with which you can automatically jump into a specific mouse layer when you move trackball. You can toggle on/off this function with the custom keycode AM_TOG.
The source code is available here.
Place the mouse sensor (PMW3360) on the sensor board in the orientation shown in the picture. Please make sure to align the ● mark on the silk with the ● mark on the board.
With the sensor pins firmly in place, secure them with tape so that they do not float. Solder 16 pins from the top side. Remove tape from the sensor and attach the lens from the top side.
Solder spring pin headers (or pin headers) to the Sensor PCB. In this buildguide spring pin headers are used as example, but you can follow the most steps when you use pin headers.
Cut spring pin headers with a cutter knife and insert them into the bottom side of the PCB as shown in the picture below. The picture shows 2x4pins. Please make sure you insert them in the correct location.
Once you insert spring pin headers to the PCB, insert sensor PCB onto it. Pay close attention to the orientation of the sensor board.
Check that the spring pin headers and sensor board are not floating, and solder for 8 pins on the sensor board side.
Once you finish soldering, please confirm that mouse cursor moves when you move close to the sensor.
If you prefer to using rotary encoder at the center of thumb clusters, insert a rotary encoder in the position shown in the picture and solder 5 pins from the bottom side.
Glue the zirconia balls to the 3D printed top case using a two-component epoxy glue.
Take a small amount of glue on the tip of a toothpick or similar tool and apply it to the three depressions on the top case.
Insert zirconia balls into the depressions with glue and leave them until they harden. If the glue overflows into the surrounding area, wipe it off before it hardens. After the zirconia balls are glued, it will look like the picture below.
After soldering, stack the top case on top of the PCB and put key switches from the corners. Pay attention not bend the pins of the key switches.
Fit the top case and the bottom case together. First, align the bottom case so that the grooves on the bottom side of it (1&2) engages with the top case.
FIt the remaining grooves into the top case. Push in the order of 3>4>5 until they snap into the place. It will be easier to fit the bottom case into the top case if you push it while pulling the bottom case toward the far side.
Put rubber feet on the bottom case.
Put ball and keycaps, and take a photo.
Several custom key codes can be set for trackball operation.
| Keycode | Description |
|---|---|
CPI_SW |
Change the CPI of the trackball. With the default firmware, each press changes the CPI in the following order: 200 -> 400 -> 800 -> 1600 -> 3200 -> 200.... |
SCRL_SW |
Changes the sensitivity of the sensor in scroll mode. The higher the value, the smaller the amount of scrolling. |
ROT_R15 |
Turns the Y axis of the mouse sensor 15 degrees clockwise. |
ROT_L15 |
Rotate the Y axis of the mouse sensor 15 degrees counterclockwise. |
SCRL_MO |
Enables scroll mode for as long as it is pressed. |
SCRL_TO |
Toggles between scroll mode and mouse mode each time it is pressed. |
SCRL_IN |
Inverts the scroll direction. |
AM_TOG |
Toggle the function of auto mouse layer. |
Custom key codes can be set in vial using the custom key code under the User tab.
If you have any problems, please contact us atTwitter.
Also, it would be very encouraging if you could upload the completed photos to social networking sites. (If you don't feel comfortable uploading your photos, you can send them directly to us via DM.)
The hashtag is #cocot38mini .