Pinout Reference¶

PCB rev 1.x

Pin assignments are verified against the Rev 1.2 schematic. GPIO18 and GPIO23 do not exist on the ESP32-PICO-MINI-02 variant used in Cyber Fidget.

GPIO assignment table¶

GPIO	Function	Type	Device / Notes
0	Boot Mode + NeoPixel Data	I/O	Momentary boot button (back) + 4x SK6812 RGBW LEDs
2	AUX Power Enable	Output	AP2112K 3.3V_RGB rail (LEDs, slider, amp, mic, SD, provisional hall sensors)
4	ACCL_INT1	Input	LIS2DH12 interrupt 1 (100k pullup)
5	SD Card SCK	Output	SPI clock for microSD (MCU_SCK)
7	OLED Reset	Output	SSD1306 display reset
12	OLED Power Enable	Output	AP2112K regulator for OLED 3.3V rail
13	Charge Enable / Red LED	Output	MCP73831 (requires solder bridge); dedicated charge status LED
14	I2S DOUT (speaker)	Output	MAX98357A DIN
15	Button 6 (SW_6) / Wake	Input	Bottom-Right; internal pullup (no ext 47k) + deep sleep ext0 wake
19	SD Card MOSI	Output	SPI data to microSD (MCU_MOSI)
20	I2C SCL	Output	Shared: OLED, LIS2DH12, MAX17048, MCP23017 x2
21	SD Card MISO	Input	SPI data from microSD (MCU_MISO)
22	I2C SDA	Bidir	Shared: OLED, LIS2DH12, MAX17048, MCP23017 x2
25	I2S LRCLK (mic)	Output	ICS-43434 MIC_WS
26	I2S BCLK (speaker)	Output	MAX98357A SPK_BCLK
27	I2S LRCLK (speaker)	Output	MAX98357A SPK_LRC
32	I2S BCLK (mic)	Output	ICS-43434 MIC_SCK
33	I2S DATA IN (mic)	Input	ICS-43434 MIC_SD
34	Button 5 (SW_5)	Input	Bottom-Left (input-only GPIO)
35	Slider ADC	Analog In	Linear slide potentiometer (HALL_LINEAR net, ADC1_CH7)
36	Button 1 (SW_1)	Input	Top-Left (input-only GPIO)
37	Button 2 (SW_2)	Input	Top-Right (input-only GPIO)
38	Button 3 (SW_3)	Input	Middle-Left (input-only GPIO)
39	Button 4 (SW_4)	Input	Middle-Right (input-only GPIO)

Button numbering

The schematic uses 1-indexed switch names (SW_1 through SW_6). The firmware uses 0-indexed button indices (0 through 5). Both refer to the same physical buttons:

Firmware index	Schematic	Position
0	SW_1	Top-Left
1	SW_2	Top-Right
2	SW_3	Middle-Left
3	SW_4	Middle-Right
4	SW_5	Bottom-Left
5	SW_6	Bottom-Right

I2C bus¶

All I2C devices share the same bus on GPIO 22 (SDA) and GPIO 20 (SCL):

Device	Address	Notes
OLED (SSD1306)	0x3C	Display
Accelerometer (LIS2DH12)	0x19	Default (0x18 if solder bridge closed)
Fuel Gauge (MAX17048)	0x36	Battery state-of-charge
I/O Expander (MCP23017) x2	—	On bus; may not be used in current firmware

I2S audio¶

Two I2S peripherals handle audio:

Speaker output (I2S port 0, TX):

Pin	Signal	Notes
GPIO 27	LRCLK	Word select
GPIO 26	BCLK	Bit clock
GPIO 14	DOUT	Data to MAX98357A

Microphone input (I2S port 1, RX):

Pin	Signal	Notes
GPIO 25	LRCLK	Word select
GPIO 32	BCLK	Bit clock
GPIO 33	DATA IN	Data from ICS-43434

SPI (SD card)¶

Pin	Signal
GPIO 5	SCK (clock)
GPIO 19	MOSI (data out)
GPIO 21	MISO (data in)

Button hardware debounce¶

Buttons SW_1 through SW_5 use hardware RC debounce:

R = 10k, C = 10nF (time constant ~100 us)
Pull-up = 47k to 3.3V

Button SW_6 (GPIO 15) uses the ESP32's internal pullup instead of an external 47k resistor. GPIO 15 also serves as the deep sleep wake pin (esp_sleep_enable_ext0_wakeup).

The firmware adds a 20 ms software debounce and a 1500 ms hold threshold on top of the hardware debounce.

Serial¶

Baud rate: 921600 (default)
USB bridge: CP2102N USB-to-UART
Default UART pins: GPIO 1 (TX), GPIO 3 (RX)