The Schiffre project is a mechanical keyboard featuring a host board and shield design, using a Flexible Flat Cable (FFC) as interconnect. All PCBs designed with Kicad 7.0. Case designed in Fusion.

In this repository you will find everything to build a Schiffre 86 board.

• The host board: schiffre_nrf
• The shield PCB: schiffre_86_pcb
• The switch plate: schiffre_86_plate, with files for production from FR4.
• The case: schiffre_86_case, designed with both 3D printing and CNC machining in mind.

In addition there is a breakout board for the 30 pin FFC connector, with a RPi Pico header in schiffre_pico.

See the production subfolders in the respective folders for the smd/assembly components. Some additional components need to be ordered seperately.

For the NRF host board (schiffre_nrf):

• One E73-2G4M08S1C bluetooth module AliExpress
• One 100mm reversible FFC calbe with 30 pins and .5mm pitch AliExpress to connect between the host and shield pcb (schiffre_86_pcb).
• A LiPo rechargable battery. There is room for a long, but narrow and thin one.
  • Thickness <= 4mm, and width <= 25mm.
  • Make sure to only use LiPos with battery protection ICs included (usually the case).
  • 4x20x60mm 600mAh AliExpress
  • 4x25x100mm 1200mAh AliExpress

For the Case (schiffre_86_case):

• M3x5.7x4.6 and M2x4x3.6 Heat-set inserts (if 3D printing the case or machining from plastics) AliExpress.
• DIN912 socket head screws: 8x M3x10mm, 4x M2x6mm AliExpress
• Plate mounting gaskets and case feet need to be 3D printed from TPU.

Below some pictures of the first build in progress. PCBs from JLCPCB, case 3D printed from PETG.

The schiffre86 supports both ANSI and ISO (Enter, split left shift) layouts, split backspace, and split spacebars. See the keyboard layout editor for details.

ZMK support works. See the schiffre branch on our zmk fork. There is a zmk-config template for the schiffre86 that you can clone to build your own keymap. It comes with support for nickcoutsos' keymap-editor.

For a precompiled version see schiffre86-schiffre_nrf-zmk.uf2 in the firmware folder.

For instructions on how to setup flashing the modules, refer to Joric's excellent nrfmicro wiki. The main thing to do is to flash the bootloader onto the E73 modules.

Schiffre is a combination of the german word Chiffre (translation of Cypher, the board this project was based on originally), and the word Schiff, which means ship or big boat, reflecting the shape of the keyboard.

• Couldn't get the XTAL to work yet
• Add some decoupling caps..
• Add a Battery switch
• Test the external power for backlight / LEDs.
• Revisit the FCC pinout, especially with other aux devices that may be on the shield board (i.e. encoders or OLEDs)
• Make FCC "reversible" i.e. mirror power pins.