Connector pinout — generated

What each module header pin and each bottom-slot breakout lead carries, and where the cat firmware reads or drives it, from firmware/cat/src/bin/main.rs (verified by tools/electronics/check_wiring_harness.py). A header's pins come from the board's netlist: its KiCad board once KiCad owns the board, the frozen baseline until then. Each wire leaves the main board from the pin named after its signal's GPIO, a rail from its slot's rail pin (below). The physical cable and wires are unknown until electronics/wiring-harness.toml says otherwise — the column is printed, never guessed. Regenerate with ./lx pcb pinout.

A signal is named by its function; silk is its compact alias, printed on the boards next to the header and carried by the frozen EasyEDA sources' nets; a bottom-slot signal's is the sensor's pin name. Matrix rows and columns count from 1; the firmware's index is one less. Directions are seen from the cat's microcontroller.

Signals

Signal	Silk	Cat side	Slot	Function
`FINGER_MATRIX_ROW_1`	`FI1`	GPIO38	fingers	matrix row 1 (firmware row 0), input, pull-up — physical bottom row
`FINGER_MATRIX_ROW_2`	`FI2`	GPIO37	fingers	matrix row 2 (firmware row 1), input, pull-up
`FINGER_MATRIX_ROW_3`	`FI3`	GPIO36	fingers	matrix row 3 (firmware row 2), input, pull-up
`FINGER_MATRIX_ROW_4`	`FI4`	GPIO35	fingers	matrix row 4 (firmware row 3), input, pull-up — physical top row
`FINGER_MATRIX_COLUMN_1`	`FO1`	GPIO1	fingers	matrix column 1 (firmware column 0), output — driven low to scan; index · outer
`FINGER_MATRIX_COLUMN_2`	`FO2`	GPIO2	fingers	matrix column 2 (firmware column 1), output — index · inner
`FINGER_MATRIX_COLUMN_3`	`FO3`	GPIO42	fingers	matrix column 3 (firmware column 2), output — middle; the left board's m0 is on column 1
`FINGER_MATRIX_COLUMN_4`	`FO4`	GPIO41	fingers	matrix column 4 (firmware column 3), output — ring
`FINGER_MATRIX_COLUMN_5`	`FO5`	GPIO40	fingers	matrix column 5 (firmware column 4), output — pinky · inner
`FINGER_MATRIX_COLUMN_6`	`FO6`	GPIO39	fingers	matrix column 6 (firmware column 5), output — pinky · outer
`FINGER_SCROLL_ENCODER_A`	`WA`	GPIO43	fingers	scroll encoder channel A, input, pull-up — EVQWGD001; fkw only
`FINGER_SCROLL_ENCODER_B`	`WB`	GPIO44	fingers	scroll encoder channel B, input, pull-up — EVQWGD001; fkw only
`THUMB_MATRIX_ROW_1`	`TI1`	GPIO4	thumb	matrix row 1 (firmware row 0), input, pull-up — physical bottom row
`THUMB_MATRIX_ROW_2`	`TI2`	GPIO5	thumb	matrix row 2 (firmware row 1), input, pull-up; `tk` only — the joystick thumb (tkj) has no keys on rows 2 and 4: its stick's axes take their pins
`THUMB_MATRIX_ROW_3`	`TI3`	GPIO6	thumb	matrix row 3 (firmware row 2), input, pull-up
`THUMB_MATRIX_ROW_4`	`TI4`	GPIO7	thumb	matrix row 4 (firmware row 3), input, pull-up; `tk` only — physical top row
`THUMB_MATRIX_COLUMN_1`	`TO1`	GPIO18	thumb	matrix column 1 (firmware column 0), output — arc positions 1–2: PCB columns a, b
`THUMB_MATRIX_COLUMN_2`	`TO2`	GPIO8	thumb	matrix column 2 (firmware column 1), output — arc position 3: PCB column c, with the center key
`THUMB_MATRIX_COLUMN_3`	`TO3`	GPIO3	thumb	matrix column 3 (firmware column 2), output — arc positions 4–5: PCB columns d, e
`THUMB_LED_DATA`	`LED_DATA`	GPIO17	thumb	LED data, output — WS2812-protocol data to LED1 DIN (RMT channel 0)
`THUMB_JOYSTICK_X`	`JX`	GPIO5	thumb	joystick axis X, analog input; `tkj` only — ADC1 channel 4: the stick's VR2 output through 1 kΩ, with 100 nF to ground at the header; row 2's pin
`THUMB_JOYSTICK_Y`	`JY`	GPIO7	thumb	joystick axis Y, analog input; `tkj` only — ADC1 channel 6: the stick's VR1 output through 1 kΩ, with 100 nF to ground at the header; row 4's pin
`BOTTOM_SENSOR_SPI_CLOCK`	`SCLK`	GPIO12	bottom	sensor SPI SCLK, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 clock, idle high
`BOTTOM_SENSOR_SPI_MOSI`	`MOSI`	GPIO11	bottom	sensor SPI MOSI, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 data out; the PMW3610's one half-duplex data line (SDIO) is this pin, then also an input
`BOTTOM_SENSOR_SPI_MISO`	`MISO`	GPIO13	bottom	sensor SPI MISO, input; `bm-pmw3389` only — SPI2 data in
`BOTTOM_SENSOR_SPI_SELECT`	`NCS`	GPIO10	bottom	sensor SPI NCS, output; `bm-pmw3389`, `bm-pmw3610` only — chip select, driven by software, idle high
`BOTTOM_SENSOR_I2C_DATA`	`SDA`	GPIO11	bottom	sensor I2C SDA, bidirectional; `bg` only — I2C0 data, open drain; the breakout's own pull-ups hold it high
`BOTTOM_SENSOR_I2C_CLOCK`	`SCL`	GPIO12	bottom	sensor I2C SCL, output; `bg` only — I2C0 clock, open drain; the breakout's own pull-ups hold it high
`BOTTOM_SENSOR_MOTION`	`MOTION`	GPIO9	bottom	sensor interrupt, input, pull-up — active low: motion or data to read; wakes the sensor task. The gyro's INT, which its driver sets active low
`BOTTOM_SENSOR_RESET`	`NRESET`	GPIO46	bottom	sensor reset, output; `bm-pmw3389` only — active low, idle high; a boot strap (Strapping pins)
`BOTTOM_ADNS5050_SPI_CLOCK`	`sclk`	GPIO14	bottom	sensor SPI SCLK, output; `bm-adns5050` only — SPI2 clock, idle high; v3's pin, main-board pin 20. The main board's battery divider (470 kΩ / 470 kΩ) hangs on it: the module never has a battery
`BOTTOM_ADNS5050_SPI_DATA`	`sdio`	GPIO13	bottom	sensor SPI MOSI, bidirectional; `bm-adns5050` only — the one half-duplex data line (SDIO), SPI2 SIO0; v3's pin, main-board pin 19
`BOTTOM_ADNS5050_RESET`	`n`	GPIO12	bottom	sensor reset, output; `bm-adns5050` only — NRESET, active low, idle high; v3's pin, main-board pin 18
`BOTTOM_ADNS5050_SPI_SELECT`	`nsc`	GPIO11	bottom	sensor SPI NCS, output; `bm-adns5050` only — NCS, driven by software, idle high; v3's pin, main-board pin 17
`BATTERY_VOLTAGE_SENSE`	`BATTERY_VOLTAGE_SENSE`	GPIO14	any	battery voltage, analog input; `battery` only — ADC2; the cell voltage through the BPI-Leaf-S3's own 470 kΩ / 470 kΩ divider (firmware/docs/battery-monitoring.md); the ADNS-5050's clock shares its pin, which build.toml [[rule]] battery-not-with-usb-only-sensor keeps apart
`3V3`	`3V3`	3.3 V rail	any	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)
`5V`	`5V`	5 V rail	any	5 V rail; `bm-adns5050` only — the main board's USB VBUS: live only while USB is plugged in, never from the battery; supply of the ADNS-5050 module alone, so its hand has no battery (build.toml [[rule]] battery-not-with-usb-only-sensor)
`GND`	`GND`	ground	any	ground — LED return, encoder common, sensor ground

Main board: BPI-Leaf-S3 (ESP32-S3)

Pins are electronics/lib/parts.toml BPI-Leaf-S3's: 1–22 the 3V3 row (J1), 23–44 the row that starts with GND (J3), each counted from the antenna end; the silkscreen names them. A rail has several pins, so each slot's rail wire has its own:

Slot	Rail	Main-board pin
thumb	`3V3`	1 (`3V3`, J1·1)
thumb	`GND`	44 (`GND`, J3·22)
fingers	`GND`	23 (`GND`, J3·1)
bottom	`3V3`	2 (`3V3`, J1·2)
bottom	`5V`	21 (`5V`, J1·21)
bottom	`GND`	22 (`GND`, J1·22)

The rail pins are a proposal: not confirmed until a cat has been wired this way.

The battery plugs into its own socket, CN1, a 2-pin MX 1.25 mm socket on the top face beside the USB-C end: pin 1 +, pin 2 -. No module wire goes to it. Source: Banana Pi's schematic (contacts) and dimension drawing (position), measured off the drawing, ±0.3 mm.

The battery's own lead (2-pin JST 1.25 mm plug) runs through the power switch (build.toml power-switch, pins 1 throw, 2 common, 3 throw, 4.7 mm pitch):

Carries	Lead	From	To
+	red	battery +	switch 2
+	red	switch 1	socket 1
-	black	battery -	socket 2

The plug's polarity is not verified: measure which contact is + before plugging it in.

Strapping pins

ESP32-S3 strapping pins the cat wires. The chip latches a strap while it is held in reset, before any firmware runs: what counts is the level the hardware holds the line at then.

Pin	Strap	Wired to	Note	Verified
GPIO46	boot mode, with GPIO0 (weak pull-down by default); gates the ROM boot log only if the UART_PRINT_CONTROL eFuse is burnt	`BOTTOM_SENSOR_RESET`	PMW3389 NRESET, `bm-pmw3389`. The breakout's NRESET pull-up holds GPIO46 at 1 during reset. A normal boot (GPIO0 = 1) ignores GPIO46, but holding BOOT (GPIO0 = 0) with GPIO46 = 1 is the combination the datasheet calls invalid, so the manual BOOT-button download may fail with a PMW3389 fitted. If it does, disconnecting the sensor's NRESET lead for the download should restore it. Whether the automatic USB reset into download mode is affected is untested as well.	no — bench check pending
GPIO3	JTAG signal source; read only if the STRAP_JTAG_SEL eFuse is burnt (not by default)	`THUMB_MATRIX_COLUMN_3`	no boot effect with default eFuses	no — bench check pending

Left finger module, 21 keys (`left-F21`) — `J1`

PH2.54-1X10P-H25 (LCSC C42431810), 1×10 vertical 2.54 mm, bottom side. KiCad project electronics/boards/left-finger-module-21-keys/left-finger-module-21-keys.kicad_pro. Pins from the frozen baseline electronics/baseline/F21-left/netlist.json (source designator H4), which owns this board until its review.

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`FINGER_MATRIX_COLUMN_1`	`FO1`	matrix column 1 (firmware column 0), output — driven low to scan; index · outer	GPIO1	26 (`GPIO1`, J3·4)	unknown
2	`FINGER_MATRIX_COLUMN_2`	`FO2`	matrix column 2 (firmware column 1), output — index · inner	GPIO2	27 (`GPIO2`, J3·5)	unknown
3	`FINGER_MATRIX_COLUMN_3`	`FO3`	matrix column 3 (firmware column 2), output — middle; the left board's m0 is on column 1	GPIO42	28 (`GPIO42`, J3·6)	unknown
4	`FINGER_MATRIX_COLUMN_4`	`FO4`	matrix column 4 (firmware column 3), output — ring	GPIO41	29 (`GPIO41`, J3·7)	unknown
5	`FINGER_MATRIX_COLUMN_5`	`FO5`	matrix column 5 (firmware column 4), output — pinky · inner	GPIO40	30 (`GPIO40`, J3·8)	unknown
6	`FINGER_MATRIX_COLUMN_6`	`FO6`	matrix column 6 (firmware column 5), output — pinky · outer	GPIO39	31 (`GPIO39`, J3·9)	unknown
7	`FINGER_MATRIX_ROW_1`	`FI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO38	32 (`GPIO38`, J3·10)	unknown
8	`FINGER_MATRIX_ROW_2`	`FI2`	matrix row 2 (firmware row 1), input, pull-up	GPIO37	33 (`GPIO37`, J3·11)	unknown
9	`FINGER_MATRIX_ROW_3`	`FI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO36	34 (`GPIO36`, J3·12)	unknown
10	`FINGER_MATRIX_ROW_4`	`FI4`	matrix row 4 (firmware row 3), input, pull-up — physical top row	GPIO35	35 (`GPIO35`, J3·13)	unknown

Right finger module, 20 keys + scroll wheel (`right-F20W`) — `J1`

KH-2.54PH180-1X13P-L11.5 (LCSC C2932703), 1×13 vertical 2.54 mm, bottom side. KiCad project electronics/boards/right-finger-module-20-keys-scroll-wheel/right-finger-module-20-keys-scroll-wheel.kicad_pro. Pins from the frozen baseline electronics/baseline/F20w-right/netlist.json (source designator H8), which owns this board until its review. Note: the source board labels pin 9 'Fo9'; it is FO6, and the KiCad redraw labels every pin with its signal's alias.

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`GND`	`GND`	ground — LED return, encoder common, sensor ground	ground	23 (`GND`, J3·1)	unknown
2	`FINGER_SCROLL_ENCODER_A`	`WA`	scroll encoder channel A, input, pull-up — EVQWGD001; fkw only	GPIO43	24 (`GPIO43`, J3·2)	unknown
3	`FINGER_SCROLL_ENCODER_B`	`WB`	scroll encoder channel B, input, pull-up — EVQWGD001; fkw only	GPIO44	25 (`GPIO44`, J3·3)	unknown
4	`FINGER_MATRIX_COLUMN_1`	`FO1`	matrix column 1 (firmware column 0), output — driven low to scan; index · outer	GPIO1	26 (`GPIO1`, J3·4)	unknown
5	`FINGER_MATRIX_COLUMN_2`	`FO2`	matrix column 2 (firmware column 1), output — index · inner	GPIO2	27 (`GPIO2`, J3·5)	unknown
6	`FINGER_MATRIX_COLUMN_3`	`FO3`	matrix column 3 (firmware column 2), output — middle; the left board's m0 is on column 1	GPIO42	28 (`GPIO42`, J3·6)	unknown
7	`FINGER_MATRIX_COLUMN_4`	`FO4`	matrix column 4 (firmware column 3), output — ring	GPIO41	29 (`GPIO41`, J3·7)	unknown
8	`FINGER_MATRIX_COLUMN_5`	`FO5`	matrix column 5 (firmware column 4), output — pinky · inner	GPIO40	30 (`GPIO40`, J3·8)	unknown
9	`FINGER_MATRIX_COLUMN_6`	`FO6`	matrix column 6 (firmware column 5), output — pinky · outer	GPIO39	31 (`GPIO39`, J3·9)	unknown
10	`FINGER_MATRIX_ROW_1`	`FI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO38	32 (`GPIO38`, J3·10)	unknown
11	`FINGER_MATRIX_ROW_2`	`FI2`	matrix row 2 (firmware row 1), input, pull-up	GPIO37	33 (`GPIO37`, J3·11)	unknown
12	`FINGER_MATRIX_ROW_3`	`FI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO36	34 (`GPIO36`, J3·12)	unknown
13	`FINGER_MATRIX_ROW_4`	`FI4`	matrix row 4 (firmware row 3), input, pull-up — physical top row	GPIO35	35 (`GPIO35`, J3·13)	unknown

Left thumb module, 11 keys (`left-T11`) — `J1`

PH2.54-1X10P-H25 (LCSC C42431810), 1×10 vertical 2.54 mm, bottom side. KiCad project electronics/boards/left-thumb-module-11-keys/left-thumb-module-11-keys.kicad_pro. Pins from the KiCad board, which owns this board; the frozen source called the header H3.

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`GND`	`GND`	ground — LED return, encoder common, sensor ground	ground	44 (`GND`, J3·22)	unknown
2	`3V3`	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	1 (`3V3`, J1·1)	unknown
3	`THUMB_LED_DATA`	`LED_DATA`	LED data, output — WS2812-protocol data to LED1 DIN (RMT channel 0)	GPIO17	10 (`GPIO17`, J1·10)	unknown
4	`THUMB_MATRIX_COLUMN_1`	`TO1`	matrix column 1 (firmware column 0), output — arc positions 1–2: PCB columns a, b	GPIO18	11 (`GPIO18`, J1·11)	unknown
5	`THUMB_MATRIX_COLUMN_2`	`TO2`	matrix column 2 (firmware column 1), output — arc position 3: PCB column c, with the center key	GPIO8	12 (`GPIO8`, J1·12)	unknown
6	`THUMB_MATRIX_COLUMN_3`	`TO3`	matrix column 3 (firmware column 2), output — arc positions 4–5: PCB columns d, e	GPIO3	13 (`GPIO3`, J1·13)	unknown
7	`THUMB_MATRIX_ROW_1`	`TI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO4	4 (`GPIO4`, J1·4)	unknown
8	`THUMB_MATRIX_ROW_2`	`TI2`	matrix row 2 (firmware row 1), input, pull-up; `tk` only — the joystick thumb (tkj) has no keys on rows 2 and 4: its stick's axes take their pins	GPIO5	5 (`GPIO5`, J1·5)	unknown
9	`THUMB_MATRIX_ROW_3`	`TI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO6	6 (`GPIO6`, J1·6)	unknown
10	`THUMB_MATRIX_ROW_4`	`TI4`	matrix row 4 (firmware row 3), input, pull-up; `tk` only — physical top row	GPIO7	7 (`GPIO7`, J1·7)	unknown

Left thumb module, 4 keys + joystick (`left-T4J`) — `J1`

PH2.54-1X10P-H25 (LCSC C42431810), 1×10 vertical 2.54 mm, bottom side. KiCad project electronics/boards/left-thumb-module-4-keys-joystick/left-thumb-module-4-keys-joystick.kicad_pro. Pins from the KiCad board, where the board was drawn (no frozen source).

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`GND`	`GND`	ground — LED return, encoder common, sensor ground	ground	44 (`GND`, J3·22)	unknown
2	`3V3`	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	1 (`3V3`, J1·1)	unknown
3	`THUMB_LED_DATA`	`LED_DATA`	LED data, output — WS2812-protocol data to LED1 DIN (RMT channel 0)	GPIO17	10 (`GPIO17`, J1·10)	unknown
4	`THUMB_MATRIX_COLUMN_1`	`TO1`	matrix column 1 (firmware column 0), output — arc positions 1–2: PCB columns a, b	GPIO18	11 (`GPIO18`, J1·11)	unknown
5	`THUMB_MATRIX_COLUMN_2`	`TO2`	matrix column 2 (firmware column 1), output — arc position 3: PCB column c, with the center key	GPIO8	12 (`GPIO8`, J1·12)	unknown
6	`THUMB_MATRIX_COLUMN_3`	`TO3`	matrix column 3 (firmware column 2), output — arc positions 4–5: PCB columns d, e	GPIO3	13 (`GPIO3`, J1·13)	unknown
7	`THUMB_MATRIX_ROW_1`	`TI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO4	4 (`GPIO4`, J1·4)	unknown
8	`THUMB_JOYSTICK_X`	`JX`	joystick axis X, analog input; `tkj` only — ADC1 channel 4: the stick's VR2 output through 1 kΩ, with 100 nF to ground at the header; row 2's pin	GPIO5	5 (`GPIO5`, J1·5)	unknown
9	`THUMB_MATRIX_ROW_3`	`TI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO6	6 (`GPIO6`, J1·6)	unknown
10	`THUMB_JOYSTICK_Y`	`JY`	joystick axis Y, analog input; `tkj` only — ADC1 channel 6: the stick's VR1 output through 1 kΩ, with 100 nF to ground at the header; row 4's pin	GPIO7	7 (`GPIO7`, J1·7)	unknown

Right thumb module, 11 keys (`right-T11`) — `J1`

A2541WV-10P (LCSC C225485), 1×10 vertical 2.54 mm, bottom side. KiCad project electronics/boards/right-thumb-module-11-keys/right-thumb-module-11-keys.kicad_pro. Pins from the KiCad board, which owns this board; the frozen source called the header H2.

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`THUMB_MATRIX_ROW_4`	`TI4`	matrix row 4 (firmware row 3), input, pull-up; `tk` only — physical top row	GPIO7	7 (`GPIO7`, J1·7)	unknown
2	`THUMB_MATRIX_ROW_3`	`TI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO6	6 (`GPIO6`, J1·6)	unknown
3	`THUMB_MATRIX_ROW_2`	`TI2`	matrix row 2 (firmware row 1), input, pull-up; `tk` only — the joystick thumb (tkj) has no keys on rows 2 and 4: its stick's axes take their pins	GPIO5	5 (`GPIO5`, J1·5)	unknown
4	`THUMB_MATRIX_ROW_1`	`TI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO4	4 (`GPIO4`, J1·4)	unknown
5	`THUMB_MATRIX_COLUMN_3`	`TO3`	matrix column 3 (firmware column 2), output — arc positions 4–5: PCB columns d, e	GPIO3	13 (`GPIO3`, J1·13)	unknown
6	`THUMB_MATRIX_COLUMN_2`	`TO2`	matrix column 2 (firmware column 1), output — arc position 3: PCB column c, with the center key	GPIO8	12 (`GPIO8`, J1·12)	unknown
7	`THUMB_MATRIX_COLUMN_1`	`TO1`	matrix column 1 (firmware column 0), output — arc positions 1–2: PCB columns a, b	GPIO18	11 (`GPIO18`, J1·11)	unknown
8	`THUMB_LED_DATA`	`LED_DATA`	LED data, output — WS2812-protocol data to LED1 DIN (RMT channel 0)	GPIO17	10 (`GPIO17`, J1·10)	unknown
9	`3V3`	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	1 (`3V3`, J1·1)	unknown
10	`GND`	`GND`	ground — LED return, encoder common, sensor ground	ground	44 (`GND`, J3·22)	unknown

Right thumb module, 4 keys + joystick (`right-T4J`) — `J1`

A2541WV-10P (LCSC C225485), 1×10 vertical 2.54 mm, bottom side. KiCad project electronics/boards/right-thumb-module-4-keys-joystick/right-thumb-module-4-keys-joystick.kicad_pro. Pins from the KiCad board, where the board was drawn (no frozen source).

Pin	Signal	Silk	Function	Cat side	Main-board pin	Cable
1	`THUMB_JOYSTICK_Y`	`JY`	joystick axis Y, analog input; `tkj` only — ADC1 channel 6: the stick's VR1 output through 1 kΩ, with 100 nF to ground at the header; row 4's pin	GPIO7	7 (`GPIO7`, J1·7)	unknown
2	`THUMB_MATRIX_ROW_3`	`TI3`	matrix row 3 (firmware row 2), input, pull-up	GPIO6	6 (`GPIO6`, J1·6)	unknown
3	`THUMB_JOYSTICK_X`	`JX`	joystick axis X, analog input; `tkj` only — ADC1 channel 4: the stick's VR2 output through 1 kΩ, with 100 nF to ground at the header; row 2's pin	GPIO5	5 (`GPIO5`, J1·5)	unknown
4	`THUMB_MATRIX_ROW_1`	`TI1`	matrix row 1 (firmware row 0), input, pull-up — physical bottom row	GPIO4	4 (`GPIO4`, J1·4)	unknown
5	`THUMB_MATRIX_COLUMN_3`	`TO3`	matrix column 3 (firmware column 2), output — arc positions 4–5: PCB columns d, e	GPIO3	13 (`GPIO3`, J1·13)	unknown
6	`THUMB_MATRIX_COLUMN_2`	`TO2`	matrix column 2 (firmware column 1), output — arc position 3: PCB column c, with the center key	GPIO8	12 (`GPIO8`, J1·12)	unknown
7	`THUMB_MATRIX_COLUMN_1`	`TO1`	matrix column 1 (firmware column 0), output — arc positions 1–2: PCB columns a, b	GPIO18	11 (`GPIO18`, J1·11)	unknown
8	`THUMB_LED_DATA`	`LED_DATA`	LED data, output — WS2812-protocol data to LED1 DIN (RMT channel 0)	GPIO17	10 (`GPIO17`, J1·10)	unknown
9	`3V3`	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	1 (`3V3`, J1·1)	unknown
10	`GND`	`GND`	ground — LED return, encoder common, sensor ground	ground	44 (`GND`, J3·22)	unknown

Bottom slot: sensor breakouts

A bottom module is a purchased breakout, wired lead by lead to the main board: no module header. Leads are named by the sensor pin the firmware driver's wiring table uses. One variant is fitted per cat (LYNXware.toml); the pins are shared, so the variants are alternatives, never together.

`bm-pmw3389` — `build.toml` part `pmw3389-breakout`

The breakout makes the sensor's 1.9 V VDD itself; VDDIO takes the 3.3 V rail, so the sensor runs on battery.

Its header, pin 1 first: 1 VIN (VDDIO), 2 MISO, 3 MOSI, 4 SCK (SCLK), 5 SS (NCS), 6 MT (MOTION), 7 GND, 8 RST (NRESET). Source: the sellers' product photos on Tindie: one row, pin 1 the square pad at VIN (citizenjoe/pmw3389-motion-sensor); the original JACK Enterprises board has the same order, labelled VI, MI, MO, SC, SS, MT, GD, RS (jkicklighter/pmw3389-motion-sensor). The pitch is not stated.

Lead	Signal	Function	Cat side	Main-board pin	Wire
SCLK	`BOTTOM_SENSOR_SPI_CLOCK`	sensor SPI SCLK, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 clock, idle high	GPIO12	18 (`GPIO12`, J1·18)	unknown
MOSI	`BOTTOM_SENSOR_SPI_MOSI`	sensor SPI MOSI, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 data out; the PMW3610's one half-duplex data line (SDIO) is this pin, then also an input	GPIO11	17 (`GPIO11`, J1·17)	unknown
MISO	`BOTTOM_SENSOR_SPI_MISO`	sensor SPI MISO, input; `bm-pmw3389` only — SPI2 data in	GPIO13	19 (`GPIO13`, J1·19)	unknown
NCS	`BOTTOM_SENSOR_SPI_SELECT`	sensor SPI NCS, output; `bm-pmw3389`, `bm-pmw3610` only — chip select, driven by software, idle high	GPIO10	16 (`GPIO10`, J1·16)	unknown
MOTION	`BOTTOM_SENSOR_MOTION`	sensor interrupt, input, pull-up — active low: motion or data to read; wakes the sensor task. The gyro's INT, which its driver sets active low	GPIO9	15 (`GPIO9`, J1·15)	unknown
NRESET	`BOTTOM_SENSOR_RESET`	sensor reset, output; `bm-pmw3389` only — active low, idle high; a boot strap (Strapping pins)	GPIO46	14 (`GPIO46`, J1·14)	unknown
VDDIO	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	2 (`3V3`, J1·2)	unknown
GND	`GND`	ground — LED return, encoder common, sensor ground	ground	22 (`GND`, J1·22)	unknown

`bm-pmw3610` — `build.toml` part `pmw3610-breakout`

3-wire SPI: SDIO is the one data line; the breakout regulates the sensor's core supply. Driver compile-checked only, not yet brought up on hardware.

Its header, pin 1 first, 2.54 mm pitch: 1 VIN (VDD), 2 GND, 3 SDIO, 4 SCLK, 5 CS (NCS), 6 MOT, 7 RST (open). Source: siderakb's pmw3610-pcb rev 2.1 (github.com/siderakb/pmw3610-pcb, J1 1×7): the design randware builds, its shipped revision unconfirmed. RST (the sensor's NRESET) stays open: the driver does not wire it.

Lead	Signal	Function	Cat side	Main-board pin	Wire
SCLK	`BOTTOM_SENSOR_SPI_CLOCK`	sensor SPI SCLK, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 clock, idle high	GPIO12	18 (`GPIO12`, J1·18)	unknown
SDIO	`BOTTOM_SENSOR_SPI_MOSI`	sensor SPI MOSI, output; `bm-pmw3389`, `bm-pmw3610` only — SPI2 data out; the PMW3610's one half-duplex data line (SDIO) is this pin, then also an input	GPIO11	17 (`GPIO11`, J1·17)	unknown
NCS	`BOTTOM_SENSOR_SPI_SELECT`	sensor SPI NCS, output; `bm-pmw3389`, `bm-pmw3610` only — chip select, driven by software, idle high	GPIO10	16 (`GPIO10`, J1·16)	unknown
MOT	`BOTTOM_SENSOR_MOTION`	sensor interrupt, input, pull-up — active low: motion or data to read; wakes the sensor task. The gyro's INT, which its driver sets active low	GPIO9	15 (`GPIO9`, J1·15)	unknown
VDD	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	2 (`3V3`, J1·2)	unknown
GND	`GND`	ground — LED return, encoder common, sensor ground	ground	22 (`GND`, J1·22)	unknown

`bm-adns5050` — `build.toml` part `adns5050-module`

3-wire SPI: SDIO is the one data line, as the PMW3610's. VDD5 takes the main board's 5 V pin, which only USB powers: the sensor is dead on battery. v3 bit-banged these pins; the SPI2 driver is compile-checked only.

Its header, pin 1 first, 2.54 mm pitch: 1 GND, 2 V (VDD5), 3 sclk (SCLK), 4 sdio (SDIO), 5 n (NRESET), 6 nsc (NCS). Source: the v3 board (EasyEDA PCB_PCB_adns5050, 2026-10-16), header H1: pin 1 the square pad, its nets and the silkscreen beside each pin; electronics/boards/bottom-module-mouse-sensor-adns5050 draws it 1:1, the header as J1.

Lead	Signal	Function	Cat side	Main-board pin	Wire
SCLK	`BOTTOM_ADNS5050_SPI_CLOCK`	sensor SPI SCLK, output; `bm-adns5050` only — SPI2 clock, idle high; v3's pin, main-board pin 20. The main board's battery divider (470 kΩ / 470 kΩ) hangs on it: the module never has a battery	GPIO14	20 (`GPIO14`, J1·20)	unknown
SDIO	`BOTTOM_ADNS5050_SPI_DATA`	sensor SPI MOSI, bidirectional; `bm-adns5050` only — the one half-duplex data line (SDIO), SPI2 SIO0; v3's pin, main-board pin 19	GPIO13	19 (`GPIO13`, J1·19)	unknown
NCS	`BOTTOM_ADNS5050_SPI_SELECT`	sensor SPI NCS, output; `bm-adns5050` only — NCS, driven by software, idle high; v3's pin, main-board pin 17	GPIO11	17 (`GPIO11`, J1·17)	unknown
NRESET	`BOTTOM_ADNS5050_RESET`	sensor reset, output; `bm-adns5050` only — NRESET, active low, idle high; v3's pin, main-board pin 18	GPIO12	18 (`GPIO12`, J1·18)	unknown
VDD5	`5V`	5 V rail; `bm-adns5050` only — the main board's USB VBUS: live only while USB is plugged in, never from the battery; supply of the ADNS-5050 module alone, so its hand has no battery (build.toml [[rule]] battery-not-with-usb-only-sensor)	5 V rail	21 (`5V`, J1·21)	unknown
GND	`GND`	ground — LED return, encoder common, sensor ground	ground	22 (`GND`, J1·22)	unknown

`bg` — `build.toml` part `mpu-6050-breakout`

The GY-521's own regulator makes the MPU-6050's supply from VCC (3.3 to 5 V; from the 3.3 V rail it drops a little, inside the chip's 2.375 to 3.46 V), and its own pull-ups hold SDA and SCL. AD0's pull-down sets the address 0x68. No driver yet.

Its header, pin 1 first, 2.54 mm pitch: 1 VCC, 2 GND, 3 SCL, 4 SDA, 5 XDA (open), 6 XCL (open), 7 AD0 (open), 8 INT. Source: Fritzing's GY-521 part (fritzing-parts, core/InvenSense_MPU6050.fzp; the board gyro_ref.py draws): one row, pin 1 VCC, the order of the board's silkscreen. XDA and XCL (the MPU-6050's auxiliary I2C) and AD0 stay open.

Lead	Signal	Function	Cat side	Main-board pin	Wire
SDA	`BOTTOM_SENSOR_I2C_DATA`	sensor I2C SDA, bidirectional; `bg` only — I2C0 data, open drain; the breakout's own pull-ups hold it high	GPIO11	17 (`GPIO11`, J1·17)	unknown
SCL	`BOTTOM_SENSOR_I2C_CLOCK`	sensor I2C SCL, output; `bg` only — I2C0 clock, open drain; the breakout's own pull-ups hold it high	GPIO12	18 (`GPIO12`, J1·18)	unknown
INT	`BOTTOM_SENSOR_MOTION`	sensor interrupt, input, pull-up — active low: motion or data to read; wakes the sensor task. The gyro's INT, which its driver sets active low	GPIO9	15 (`GPIO9`, J1·15)	unknown
VCC	`3V3`	3.3 V rail — supply of the thumbs' LEDs, the joystick thumb's stick and the bottom slot's sensor breakout (no GPIO can source it)	3.3 V rail	2 (`3V3`, J1·2)	unknown
GND	`GND`	ground — LED return, encoder common, sensor ground	ground	22 (`GND`, J1·22)	unknown

Provenance

electronics/wiring-harness.toml sha256 0985ced98b402be8…
firmware/cat/src/bin/main.rs pin assignments (check_wiring_harness.firmware_map) sha256 4c693529ce1f3801…
electronics/lib/parts.toml BPI-Leaf-S3 pins sha256 b5f220238e2207a7…
electronics/baseline/F21-left/netlist.json H4 pin → net sha256 f2d4384fe3bd7bfc…
electronics/baseline/F20w-right/netlist.json H8 pin → net sha256 6ba9386f0652cb58…
electronics/boards/left-thumb-module-11-keys/left-thumb-module-11-keys.kicad_pcb J1 pin → net sha256 78d13bf845ee2d0e…
electronics/boards/left-thumb-module-4-keys-joystick/left-thumb-module-4-keys-joystick.kicad_pcb J1 pin → net sha256 44a96e81c31bdbbd…
electronics/boards/right-thumb-module-11-keys/right-thumb-module-11-keys.kicad_pcb J1 pin → net sha256 38651e03ef8d303c…
electronics/boards/right-thumb-module-4-keys-joystick/right-thumb-module-4-keys-joystick.kicad_pcb J1 pin → net sha256 5d4ad4a2363863bd…
command: python3 tools/electronics/pinout.py

Connector pinout — generated

Signals

Main board: BPI-Leaf-S3 (ESP32-S3)

Strapping pins

Left finger module, 21 keys (left-F21) — J1

Right finger module, 20 keys + scroll wheel (right-F20W) — J1

Left thumb module, 11 keys (left-T11) — J1

Left thumb module, 4 keys + joystick (left-T4J) — J1

Right thumb module, 11 keys (right-T11) — J1

Right thumb module, 4 keys + joystick (right-T4J) — J1