Microcontroller

LIA is built around an ESP32-S3-MINI-1-N8 (U1), which runs the Meshtastic firmware and talks to every other peripheral on the board over SPI, I2C, and UART. This page documents how its pins are wired, straight from the uController schematic sheet.

Pinout

Module pin	GPIO	Signal	Function
3	—	3V3	3.3 V supply
45	—	EN	Enable/reset — 10 kΩ pull-up, 1 µF decouple, reset button
4	GPIO0	IO0	Boot mode strap + BOOT button
8	GPIO4	SDA	I2C data — shared bus (IMU and fuel gauge, both boards — see Battery)
9	GPIO5	SCL	I2C clock — shared bus
10	GPIO6	IMU_INT	Accelerometer interrupt (see Accelerometer)
12	GPIO8	RESET	LoRa radio reset (SX1262)
13	GPIO9	BUSY	LoRa radio busy (SX1262)
14	GPIO10	NSS	LoRa radio SPI chip select (SX1262)
15	GPIO11	MOSI	LoRa radio SPI MOSI (SX1262)
16	GPIO12	SCK	LoRa radio SPI clock (SX1262)
17	GPIO13	MISO	LoRa radio SPI MISO (SX1262)
18	GPIO14	DIO	LoRa radio DIO interrupt (SX1262)
21	GPIO17	Tx	UART to GNSS module (SAM-M10Q)
22	GPIO18	Rx	UART from GNSS module (SAM-M10Q)
23	GPIO19	IO19	USB D−
24	GPIO20	IO20	USB D+
5	GPIO1	CHG	Battery charger status
6	GPIO2	STBY	Battery charger standby status
19	GPIO15	BMS	Beacon Mode Selector — physically 3-position; see Power Management for the OFF position
25	GPIO21	PPC	Peripheral power control
36	GPIO40	Lred	Status LED, red channel — see RGB LED
37	GPIO41	Lgreen	Status LED, green channel — see RGB LED
38	GPIO42	Lblue	Status LED, blue channel — see RGB LED
39	—	TXD0	UART0 (reserved, not connected in this design)
40	—	RXD0	UART0 (reserved, not connected in this design)
—	—	GND	Ground (multiple pins)

See also: BOM, Schematics, LoRa, GPS, and Building the Firmware (this pinout is what the lia_v1 board variant is built from).