GY-273 HMC5883L compass with ESP32

Supply 3.3-5 V Bus I2C I2C address 0x1E Measures magnetic field, heading

Pins and ESP32 wiring

Pin	Role	ESP32 pin	Notes
VCC	Power	3V3
GND	Ground	GND
SCL	I2C clock (SCL)	D22
SDA	I2C data (SDA)	D21
DRDY	Interrupt	D35	Data ready, optional

Suggested wiring for the 30-pin ESP32 DevKit, avoiding flash, input-only and strapping pins. BoardPilot checks it for you as you wire.

Check it is the real chip

Read register 0x0A: a genuine part answers 0x48. BoardPilot does this automatically in “Debug a problem”.

Starter code (Arduino)

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);  // SDA = GPIO 21, SCL = GPIO 22
  Wire.beginTransmission(0x1E);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "GY-273 HMC5883L compass found at 0x1E" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Sources

Honeywell HMC5883L datasheet, Identification register A (0x0A) reads 0x48 (ASCII H)
Honeywell HMC5883L datasheet, I2C address 0x1E

Try it in 3D in BoardPilot

BoardPilot Part data (JSON)

Part data: CC BY 4.0, free to reuse with credit to BoardPilot.