INA226 with ESP32

Specifications

Power and logic levels

3.3 V: safe to connect directly

ESP32 pins, including those on a display board's connectors, work at 3.3 V and are not 5 V tolerant. Modules differ, so if in doubt, measure the signal before you connect it.

Wiring

Arduino code

#include <Wire.h>

const int SDA_PIN = 8, SCL_PIN = 9;
const uint8_t ADDR = 0x40;
const float SHUNT_OHM = 0.1;

int16_t readReg(uint8_t reg) {
  Wire.beginTransmission(ADDR);
  Wire.write(reg);
  Wire.endTransmission();
  Wire.requestFrom(ADDR, (uint8_t)2);
  int16_t v = Wire.read() << 8;
  return v | Wire.read();
}

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);
}

void loop() {
  float shuntV = readReg(0x01) * 2.5e-6;       // 2.5 uV per step
  float busV = (uint16_t)readReg(0x02) * 1.25e-3;  // 1.25 mV per step
  float amps = shuntV / SHUNT_OHM;
  Serial.printf("%.3f V  %.3f A  %.2f W\n", busV, amps, busV * amps);
  delay(1000);
}

No extra library needed. Compiled for ESP32-S3 with arduino-esp32 3.x. Not yet tested by us on a physical sensor. Change the pins to match your board.

On a display

Read the value in your sketch and pass it to a label, or send it over MQTT and show it with an MQTT value in the editor.

Boards with a ready connector

Only boards whose connectors we have surveyed. Others may still work on free GPIOs.

Good to know

• The shunt sets the current limit: about 0.8 A with 0.1 Ω.
• Fuse the measured circuit.
• Check the address: modules differ.
• Do not use it on mains.

What it is good for

• Battery monitors
• Solar charge displays
• Bench supply readouts

FAQ

Sources

• https://esp32.co.uk/ina226-esp32-esphome-dc-voltage-current-power-energy/
• https://components.espressif.com/components/pkolt/ina226/versions/1.0.0/readme?language=ru
• https://www.atomic14.com/esp32/sensors/ina226/

Related parts

• INA219
• ACS712 current sensor