INA219 with Arduino Uno R3

Wiring for the INA219 current + voltage monitor on the Arduino Uno R3 (ATmega328P, 5 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

INA219 pin	Role	Arduino Uno R3 pin	Notes
VCC	Power	5V
GND	Ground	GND
SCL	I2C clock (SCL)	A5 (PC5)
SDA	I2C data (SDA)	A4 (PC4)
VIN-	Not wired to the board	not connected	To the load. Measured circuit only, up to 26 V
VIN+	Not wired to the board	not connected	From the supply. Measured circuit only, up to 26 V

Check before you power it on

Supply: 5 V from the 5V pin.
I2C uses the board’s default pins A4 (SDA) and A5 (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 = A4, SCL = A5 (the board's default I2C pins)
  Wire.beginTransmission(0x40);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "INA219 current + voltage monitor found at 0x40" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Arduino board: arduino:avr:uno.

Questions

Which Arduino Uno R3 pins do I use for the INA219?

VCC → 5V, GND → GND, SCL → A5 (PC5), SDA → A4 (PC4).

Does the INA219 work with the Arduino Uno R3 at 5 V?

Yes: the INA219 runs at 3.3-5 V and the Arduino Uno R3 uses 5 V signals, so no level shifting is needed.

What is the I2C address of the INA219?

0x40 or 0x41 or 0x44 or 0x45. 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 Arduino Uno R3 pinout · INA219 current + voltage monitor: all pins and data

The INA219 on other boards

ESP32 DevKit Arduino Mega 2560 R3 Arduino Nano WeAct Black Pill STM32F411CE ESP32-C3-DevKitM-1 ESP32-S3-DevKitC-1 Nordic nRF52840 DK NUCLEO-F401RE Raspberry Pi Pico 2 Raspberry Pi Pico W Raspberry Pi Pico Teensy 4.1

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