Xiao Flex v3

The XIAO Flex provides 16 pins, low voltage, high voltage battery protection.

While 16 pins is 5 more than the standard XIAO nrf52840 it still has some limitations.
As a result different pins can be changed with solderable jumper pads.
These pads are swapping a pin from one 'use' to another. But only one use per pin!

RGB power is switched with a physical switch disconnecting the full LED string from VCC. This drastically improves battery life over just having a software toggle that disables the data signal. 

Pinout:
Rows:
R1: 1.12
R2: 1.13
R3:  0.02
R4: 0.03
R5: 0.28 - Swappable for LED
R6: 1.11 - Swappable for TB1
Thumbs Row: 0.10 - Always have this as the last row in your matrix IF you're using the flexible ribbon for the Skree beans (thumb key single key pcbs). 

Columns:
C1: 0.09
C2: 1.14
C3: 1.15
C4: 1.10
C5: 1.00
C6: 0.16
C7: 0.29 -Swappable for TB2

SPI / I2C
MOSI+MISO: 0.04
SCK: 0.05
TB1: 1.11 - Requires no R6
TB2:  0.29 - Requires no C7

LED: Optional with either R5 or TB2

Battery power is supplied from a optional LIR2450 rechargeable battery with ~120mah. Or simply solder whatever single cell Lipo (3.7v rechargeable) that you have!
Note charge speed is limited to 100mah. Large batteries will take a considerable time to charge. 18650s are recommended removed and manually charged. 

Example ZMK code can be found at : https://github.com/WainingForests/ZMK-XIAOv3
There are branches for configuration with a trackball too!