GPIO pinout

Quick reference for GPIO assignments on the ED1 Citilab Board.

GPIO assignment table

GPIO	Function	ID	Dir	Notes
0	Boot/Flash	-	I	Boot mode select
2	Touch Left	`btn_left`	I	Capacitive touch
4	Touch Up	`btn_up`	I	Capacitive touch
5	TFT CS	`internal_display`	O	SPI chip select
9	TFT DC	`internal_display`	O	Data/Command
10	TFT Reset	`internal_display`	O	Display reset
12	LED Matrix	`led_matrix_light`	O	WS2812 data
13	Touch Down	`btn_down`	I	Capacitive touch
14	Touch X	`btn_x`	I	Capacitive touch
15	Touch OK	`btn_ok`	I	Capacitive touch
18	SPI CLK	`spi`	O	SPI clock
19	SPI MISO	`spi`	I	SPI data in
21	I2C SDA	`bus_i2c`	I/O	I2C data
22	I2C SCL	`bus_i2c`	O	I2C clock
23	SPI MOSI	`spi`	O	SPI data out
26	Buzzer	`buzzer_output`	O	PAM8301 amp
27	Touch Right	`btn_right`	I	Capacitive touch
34	Light Sensor	`light_sensor`	I	ADC input
32	IR TX	`remote_transmitter`	O	Rev 1.0 only
33/35	IR RX	`remote_receiver`	I	GPIO33 Rev 1.0, GPIO35 Rev 2.3

ID = ESPHome component ID. Dir = I (input), O (output), I/O (bidirectional).

Bus assignments

SPI bus

GPIO18 (CLK), GPIO23 (MOSI), GPIO19 (MISO). Used by TFT Display (ST7735).

I2C bus

GPIO21 (SDA), GPIO22 (SCL). Rev 2.3:

Device	Address	Function
MXC6655XA	0x15	Accelerometer
MCP23009	0x20	I/O Expander (stepper motors)

Rev 1.0:

Device	Address	Function
LIS3DH	0x19	Accelerometer
MCP23017	0x20	I/O Expander (16 GPIO pins)

MCP23009 GPIO mapping (stepper motors)

GPIO	Coil	Driver	Motor
GP0	D	ULN2004A U8	M2
GP1	C	ULN2004A U8	M2
GP2	B	ULN2004A U8	M2
GP3	A	ULN2004A U8	M2
GP4	D	ULN2004A U7	M1
GP5	C	ULN2004A U7	M1
GP6	B	ULN2004A U7	M1
GP7	A	ULN2004A U7	M1

Touch button mapping

UP
GPIO4

LEFT
GPIO2

TFT Display

RIGHT
GPIO27

OK
GPIO15

X
GPIO14

DOWN
GPIO13

Analog inputs

GPIO	Function	ADC	Attenuation
34	Light Sensor	ADC1_CH6	12dB (0–3.3V)

LED matrix

Data Pin: GPIO12
Type: WS2812X (GRB color order)
Count: 256 LEDs (32 columns x 8 rows)
Layout: Serpentine (zigzag) pattern

Pixel mapping

Column:  0   1   2   3  ...
Row 0:   0   15  16  31 ...
Row 1:   1   14  17  30 ...
Row 2:   2   13  18  29 ...
...
Row 7:   7   8   23  24 ...

Formula:

if (x % 2 == 0)
    pixel = (x * 8) + y;
else
    pixel = (x * 8) + (7 - y);

Expansion connectors

Analog ports - J5 (left side)

Input-only ADC pins, directly connected to ESP32. Active-low.

Port	GPIO	ADC	Notes
A1	GPIO36	ADC1_CH0	SVP
A2	GPIO37	ADC1_CH1	-
A3	GPIO38	ADC1_CH2	-
A4	GPIO39	ADC1_CH3	SVN

All analog ports share a 3-pin connector: S (signal), + (3.3V), - (GND).

Digital ports - J2 (right side)

Port	GPIO	ADC	Notes
D1	GPIO12	ADC2_CH5	LED matrix data
D2	GPIO25	ADC2_CH8	DAC1
D3	GPIO32	ADC1_CH4	-
D4	GPIO26	ADC2_CH9	Buzzer output

All digital ports share a 3-pin connector: S (signal), + (5V), - (GND). Note: D1 (GPIO12) and D4 (GPIO26) are used internally. D2 (GPIO25) and D3 (GPIO32) are available for external use.

I2C/serial - J6 (bottom left)

Pin	Label	GPIO	Function
1	DA	GPIO21	I2C SDA
2	CL	GPIO22	I2C SCL
3	TX	GPIO1	UART TX
4	RX	GPIO3	UART RX

Grove connector (J11)

Pin	Signal	Connection
1	VDD33	3.3V
2	GND	Ground
3	SDA	GPIO21
4	SCL	GPIO22

Stepper motor connectors

M1 & M2 (28BYJ-48)

Pin	Signal
1	Coil A
2	Coil B
3	Coil C
4	Coil D
5	VDD5 (common)

Controlled via MCP23009 I/O expander and ULN2004A drivers.

Reserved/internal GPIOs

These GPIOs are used internally by the ESP32 or board hardware:

GPIO	Internal Use
6-11	Flash (do not use)
16, 17	Flash CS/SDO
36, 39	Sensor VP/VN

Getting started

Hardware

ESPHome

Project

GPIO assignment table

Bus assignments

SPI bus

I2C bus

MCP23009 GPIO mapping (stepper motors)

Touch button mapping

Analog inputs

LED matrix

Pixel mapping

Expansion connectors

Analog ports - J5 (left side)

Digital ports - J2 (right side)

I2C/serial - J6 (bottom left)

Grove connector (J11)

Stepper motor connectors

M1 & M2 (28BYJ-48)

Reserved/internal GPIOs

​GPIO assignment table

​Bus assignments

​SPI bus

​I2C bus

​MCP23009 GPIO mapping (stepper motors)

​Touch button mapping

​Analog inputs

​LED matrix

​Pixel mapping

​Expansion connectors

​Analog ports - J5 (left side)

​Digital ports - J2 (right side)

​I2C/serial - J6 (bottom left)

​Grove connector (J11)

​Stepper motor connectors

​M1 & M2 (28BYJ-48)

​Reserved/internal GPIOs

GPIO assignment table

Bus assignments

SPI bus

I2C bus

MCP23009 GPIO mapping (stepper motors)

Touch button mapping

Analog inputs

LED matrix

Pixel mapping

Expansion connectors

Analog ports - J5 (left side)

Digital ports - J2 (right side)

I2C/serial - J6 (bottom left)

Grove connector (J11)

Stepper motor connectors

M1 & M2 (28BYJ-48)

Reserved/internal GPIOs