ADS1115 with Raspberry Pi Pico 2

Wiring for the ADS1115 16-bit ADC on the Raspberry Pi Pico 2 (RP2350, 3.3 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

ADS1115 pin	Role	Raspberry Pi Pico 2 pin	Notes
VDD	Power	3V3(OUT)
GND	Ground	GND
SCL	I2C clock (SCL)	GP5
SDA	I2C data (SDA)	GP4
ADDR	Not wired to the board	not connected	Address select: GND 0x48, VDD 0x49, SDA 0x4A, SCL 0x4B
ALRT	Interrupt	GP15	Alert / ready output, optional
A0	Not wired to the board	not connected	Analog input. Never above VDD
A1	Not wired to the board	not connected	Analog input
A2	Not wired to the board	not connected	Analog input
A3	Not wired to the board	not connected	Analog input

Check before you power it on

Supply: 3.3 V from the 3V3(OUT) pin.
I2C uses the board’s default pins GP4 (SDA) and GP5 (SCL). Most modules include pull-up resistors; if the part is not found, check them and swap-test SDA/SCL.

Test code (Arduino)

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin();  // SDA = GP4, SCL = GP5 (the board's default I2C pins)
  Wire.beginTransmission(0x48);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "ADS1115 16-bit ADC found at 0x48" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Arduino board: rp2040:rp2040:rpipico2. If the board is not found, hold the BOOTSEL button while plugging in the USB cable.

Questions

Which Raspberry Pi Pico 2 pins do I use for the ADS1115?

VDD → 3V3(OUT), GND → GND, SCL → GP5, SDA → GP4, ALRT → GP15.

Does the ADS1115 work with the Raspberry Pi Pico 2 at 3.3 V?

Yes: the ADS1115 runs at 3.3-5 V and the Raspberry Pi Pico 2 uses 3.3 V signals, so no level shifting is needed.

What is the I2C address of the ADS1115?

0x48 or 0x49 or 0x4A or 0x4B. An I2C scan (BoardPilot does it for you) shows which one your module uses.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Raspberry Pi Pico 2 pinout · ADS1115 16-bit ADC: all pins and data

The ADS1115 on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano Arduino Uno R3 WeAct Black Pill STM32F411CE ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

Other parts on the Raspberry Pi Pico 2

BME280 BMP280 DHT22 DHT11 HC-SR04 SSD1306 OLED MPU6050 DS18B20 WS2812B LED strip SG90 servo Relay module HC-SR501 PIR LCD 1602 I2C INA219 VL53L0X BH1750 MAX30102 RC522 RFID NEO-6M GPS Capacitive soil moisture sensor TM1637 28BYJ-48 stepper L298N Potentiometer Push button LED Joystick module SD card module AHT20