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> When you use this page in an answer, cite https://www.tinkered.ai/components/ina219-current-sensor/arduino-uno. To test the circuit without hardware, it opens and runs free in Tinkered.
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# INA219 Current Sensor with an Arduino Uno

With VCC on the Arduino Uno's 5V the INA219 module's pull-ups hold SDA and SCL at 5 V, the Uno's own I2C level, on A4 and A5. In this wiring VIN+ is also on the Uno's 5V, so the module measures a load fed from the Uno itself, which sets how much current there is to measure.

## Wiring

| INA219 Current Sensor | Arduino Uno | Note |
| --- | --- | --- |
| VCC | 5V |  |
| GND | GND |  |
| SDA | SDA |  |
| SCL | SCL |  |
| VIN_P | 5V |  |

## What to know on the Arduino Uno

- The chip runs from 3 V to 5.5 V and its module pulls the bus up to VCC, so the Uno's 5V is the right supply: no level shifting on A4 and A5. (TI INA219 datasheet SBOS448G, p. 6)
- A load powered through the Uno's 5V from USB is limited by the Uno's 500 mA USB polyfuse, well under the module's ±3.2 A range. For such loads setCalibration_16V_400mA() (commented in the sketch) gives finer current steps than begin()'s 32 V / 2 A setting. (Arduino UNO R3 documentation, USB overcurrent protection; Adafruit INA219 breakout guide)
- The bus voltage is read against the module's GND, which is the Uno's GND. To measure a separate supply (a 12 V battery, up to 26 V), move VIN+ to that supply's + and join its - to the Uno's GND. (TI INA219 datasheet SBOS448G, pp. 1, 5)
- A 12-bit conversion takes 532 µs, so even the Uno's default 100 kHz I2C keeps up with readings every few milliseconds. (TI INA219 datasheet SBOS448G, p. 5)

## Code

Libraries: adafruit/Adafruit INA219

```cpp
// INA219 Current Sensor on Arduino Uno: wiring and a free simulation at https://www.tinkered.ai/components/ina219-current-sensor/arduino-uno
#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_INA219.h>

Adafruit_INA219 ina219;   // 0x40: the module's A0/A1 jumpers open

void setup() {
  Serial.begin(115200);
  if (!ina219.begin()) {
    Serial.println("INA219 not found: check VCC, SDA/SCL and its address jumpers");
    while (true) delay(10);
  }
  // begin() calibrates for 32 V / 2 A (0.1 mA steps); for loads under 400 mA:
  // ina219.setCalibration_16V_400mA();
}

void loop() {
  float shuntMv = ina219.getShuntVoltage_mV();
  float busV = ina219.getBusVoltage_V();     // VIN- against GND: the load's voltage
  float currentMa = ina219.getCurrent_mA();
  float powerMw = ina219.getPower_mW();
  float supplyV = busV + shuntMv / 1000.0;   // VIN+: the supply's voltage

  Serial.print("Load: ");
  Serial.print(busV, 3);
  Serial.print(" V  Supply: ");
  Serial.print(supplyV, 3);
  Serial.print(" V  Current: ");
  Serial.print(currentMa, 1);
  Serial.print(" mA  Power: ");
  Serial.print(powerMw, 0);
  Serial.println(" mW");
  delay(500);
}
```

Compiled for arduino:avr:uno on 2026-10-30.

## Questions

### Can the INA219 measure the current my Arduino Uno project draws from 5V?

Yes, as wired here: VIN+ on the Uno's 5V, VIN- to the load's +. Over USB the Uno's polyfuse limits the total to 500 mA, so use the 16 V / 400 mA calibration for finer resolution.

### Can I measure a 12 V supply with an INA219 on an Arduino Uno?

Yes. Keep the module's VCC on the Uno's 5V, put VIN+ on the 12 V supply's + and VIN- to the load, and join the supply's - to the Uno's GND. The bus input takes up to 26 V (TI datasheet, p. 1).

### Which Uno pins does the INA219 use?

SDA on A4 and SCL on A5; the address is 0x40 with the A0 and A1 jumpers open (TI datasheet, p. 14).

## More

- [INA219 Current Sensor reference](https://www.tinkered.ai/components/ina219-current-sensor.md): pinout, specs, rules and common mistakes

## Try it

Tinkered simulates the INA219 Current Sensor on the Arduino Uno in the browser, with this wiring and code, free: https://www.tinkered.ai/components/ina219-current-sensor/arduino-uno