# CMDR keyboard 42 (swedish layout)

_This HW(PCB) was original made for use with the TeensyLC module and is reused by patching it to fit the rp2040-zero module_

![image](keyboard_42_green.jpg)

## Layout

```text
 Layer 0
 ---------------------------------------      ---------------------------------------
 |  Tab  |  Q  |  W  |  E  |  R  |  T  |      |  Y  |  U  |  I  |  O  |  P  |   Å   |
 | LCtrl |  A  |  S  |  D  |  F  |  G  |      |  H  |  J  |  K  |  L  |  Ö  |   Ä   |
 | Shift |  Z  |  X  |  C  |  V  |  B  |      |  N  |  M  | ,;  | .:  | -_  | Shift |
 --------------------| Alt | Fn  | Spc |      |Enter| Fn  |AG+Fn|--------------------
                     -------------------      -------------------
 Layer 1 (Fn)
 ---------------------------------------      ---------------------------------------
 |  Esc  | F1  | F2  | F3  | F4  | F5  |      | F6  | F7  | F8  | F9  | F10 |  BSpc |
 | LCtrl | 1!  | 2"@ | 3#£ | 4¤$ | 5%  |      | 6&  | 7/{ | 8([ | 9)] | 0=} | Enter |
 | Shift | 6&  | 7/{ | 8([ | 9)] | 0=} |      | <>| | ´`± | '*´ | ¨^~ | +?\ | Shift |
 --------------------| Alt | Fn  | Spc |      | BSpc| Fn  |AG+Fn|--------------------
                     -------------------      -------------------
 Layer 2 (Fn + Fn)
 ---------------------------------------      ---------------------------------------
 |  Esc  | F11 | F12 | F13 | F14 |PrSrc|      |  §  | SLk | Gui | OSLk| CpLk|  BSpc |
 | LCtrl | F15 | F16 | F17 | F18 | F19 |      | Left| Down| Up  |Right| Del | Enter |
 | Shift | F20 | F21 | F22 | F23 | F24 |      | Home| PgD | PgU | End | Ins | Shift |
 --------------------| Alt | Fn  | Spc |      | BSpc| Fn  |AG+Fn|--------------------
                     -------------------      -------------------
```

## Features

- 42 keys "Split" keyboard layout. 36 finger buttons and 6 thumb buttons.
- Extreme low profile (only one pcb).
- Cost efficient solution with one pcb and one 3D printed cover.
- Function layers provide three active maps (primary + two Fn layers) with sticky-lock support.
- High-speed key scanning: 250 µs cadence with enhanced 5-scan debounce (1.25ms) and anti-bounce protection to prevent double characters.
- Status indication driven by the joystick-style heartbeat model:
  - Heartbeat green while waiting for USB enumeration.
  - Solid green during normal operation; automatic heartbeat idle animation after 5 s inactivity.
  - Blue solid / flashing when sticky lock is armed / latched.
  - Red solid on firmware error, red flashing for Caps Lock.
  - LED turns off during USB suspend for power savings.
- Power management for USB suspend/resume:
  - Automatic power saving when USB host suspends device.
  - Reduced key scanning frequency (20x slower) during suspend.
  - Wake-on-input detection for any key press.
  - Immediate resume response when keys are pressed.

## Build environment rp2040 Zero

Rust embedded, rp2040 HAL

- Cargo (cargo.toml)
  - rustup target add thumbv6m-none-eabi
  - cargo install elf2uf2-rs --locked
- Flashing via rp2040 USB bootloader
  - Pressing reset/boot button on rp2040 Zero board
  - Pressing upper left corner on the keyboard when connecting the usb cable

## Hardware

[Schematics](eCAD/cmdr_mainboard_42_v1.pdf)  
[patch instruction](/eCAD/rp2040_42_patch_instruction.md)

- 1x rp2040 Zero
- 36x Cherry MX compatible switches
- 6x Kailh Choc low profile switches
- 42x 1N4148 diodes
- 1x PCB [Gerber files](eCAD/cmdr_mainboard_42_gerber_v1.zip) (please see [patch instructions](/eCAD/rp2040_42_patch_instruction.md))
- 1x MCU cover [STL file](mCAD/cmdr_keyboard_42_cover.stl)
- 1x 6x3 Cherry MX mounting jig (optional) [STL file](mCAD/cmdr_mounting_jig-MountingJig.stl)

---