Pin Reference

StickS3 Port Assignments

Port A (I2C)

Pin	GPIO	Function
SCL	GPIO 1	I2C Clock
SDA	GPIO 2	I2C Data
VCC	3.3V	Power
GND	GND	Ground

Cable colors: Yellow = SDA, White = SCL, Red = VCC, Black = GND

Built-in Features

Feature	GPIO	Notes
Button A (front)	GPIO 35	User button
IR Transmitter	GPIO 4	Infrared LED
RGB LED (NeoPixel)	GPIO 21	WS2812 addressable LED
Display	SPI	0.49” OLED, 64x32
Buzzer	GPIO 2	Shared with SDA on Port A

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Common I2C Addresses

When you run an I2C scan, these are common device addresses:

Address	Device
0x38	Atom Motion base
0x44	SHT30 (ENV III temperature/humidity)
0x5D	AXP2101 (Power management)
0x68	MPU6886 (IMU / accelerometer)
0x76	BMP280 (Pressure sensor)

I2C Scanner Code

import machine
i2c = machine.I2C(0, scl=machine.Pin(1), sda=machine.Pin(2), freq=100000)
devices = i2c.scan()
print("I2C devices found:", [hex(addr) for addr in devices])

Caution

Two sensors cannot share the same I2C address on the same bus. If you see conflicts, use different ports or an I2C multiplexer.

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Common Setups

Setup A: ENV III Sensor (I2C) on Port A

import machine
from unit import ENV_III
import time

# Port A is I2C0 on pins 1 (SCL) and 2 (SDA)
i2c = machine.I2C(0, scl=machine.Pin(1), sda=machine.Pin(2), freq=100000)
env = ENV_III(i2c)

# Wait for sensor startup
time.sleep(1)

# Read (with error handling)
try:
    temp, hum, press = env.read()
except:
    print("Sensor not ready")

Setup B: Servo on Header Pin (PWM)

from machine import Pin, PWM
import time

# Pin 2 is common for servo on header
servo = PWM(Pin(2), freq=50)

def set_angle(angle):
    # Convert 0-180 to duty cycle
    duty = int((angle / 180 * 2 + 0.5) / 20 * 1023)
    servo.duty(duty)

# Test
set_angle(90)
time.sleep(1)
set_angle(0)

Setup C: Multiple I2C Sensors (HUB Required)

# Scan first to see addresses
devices = i2c.scan()
print("Found:", [hex(d) for d in devices])

# If you see conflicts (two 0x44), you need:
# 1. Different I2C ports (Port A vs Port B), OR
# 2. I2C multiplexer, OR
# 3. Different sensor models with different addresses