Xiao nRF52840 breakout board with JST and FPC connections for easy building.
PCB project files are for EasyEDA - Standard. Simply install, and import the Schematic and PCB files.
Dimensions H33.4mm x W39.4mm Battery extends 5mm past top for easy removal (Recommend Kapton tape if shorts are a concern for some reason)
Components and ICs Seeed Studios Xiao nRF52840 Battery mount - LR2450 (alternatively remove mount and solder to pads polarity is on board) Battery low voltage cutoff from FS312F-6 Battery Protection IC and Cutoff Mosfet from FS8205 Shift register - RS0101YH6 Power switch is cutting BATT+ from XIAO.
FPC connections 8p and 10p (thumbs) 0.5mm pitch. The headers dual contact headers. JST SH headers are used. All 6p
LED & Shift Register Circuit; The switch toggles from 5v with shift register data, to no contact (half switch protection), to 3.3v (from XIAO) and 3.3v pin logic.
Thumb row selection is done via a 2.54mm jumper. Unconnected will leave the Row pad disconnected.
V1.1 - Poly fuse added to GND side. Added through holes for regulated (switch) LED power and LED data. V1.2 - Added through holes for 1.10 1.00 and 0.16 for SPI / I2C / more columns or rows if wanted!
Pinout
C1 - P0.05 R1 - P0.02 LEDDATA - P0.09
C2 - P1.11 R2 - P0.03
C3 - P1.12 R3 - P0.28
C4 - P1.13 R4 - P0.29
C5 - P1.14 R5 - P0.04
C6 - P1.15 R6 - P0.10
FPC specific pinout: Perspective: viewing device with USB closer to you. Top is farthest away from USB.
Fingers - GND
R4
GND
R3
GND
R2
GND
R1
GND
Fingers LED
LED+
LEDDATA
R5
R4
R3
R2
R1
GND
Thumbs
GND
Thumbs
GND
THUMBROW - Jumper Selection for R5 or R6
C1
C2
C3
C4
C5
C6
GND
LED+
Access to all work is under Copyright from Marshall Somerville 2023 CC BY-NC-SA 4.0