BH1750 with ESP32-C3-DevKitM-1

Wiring for the GY-302 BH1750 light sensor on the ESP32-C3-DevKitM-1 (ESP32-C3, 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

BH1750 pin	Role	ESP32-C3-DevKitM-1 pin	Notes
VCC	Power	3V3
GND	Ground	GND
SCL	I2C clock (SCL)	9
SDA	I2C data (SDA)	8
ADDR	Not wired to the board	not connected	Address select: LOW or open = 0x23, HIGH = 0x5C

Check before you power it on

Supply: 3.3 V from the 3V3 pin.
I2C can use almost any pins on the ESP32-C3-DevKitM-1; 8 (SDA) and 9 (SCL) are the defaults. If the part is not found, the wires may be crossed: try Wire.begin with the two exchanged.

Test code (Arduino)

#include <Wire.h>

void setup() {
  Serial.begin(115200);
  Wire.begin(8, 9);  // SDA = 8, SCL = 9
  Wire.beginTransmission(0x23);
  bool found = Wire.endTransmission() == 0;
  Serial.println(found ? "GY-302 BH1750 light sensor found at 0x23" : "Not found: check power, GND and SDA/SCL");
}

void loop() {}

Arduino board: esp32:esp32:esp32c3. If uploading does not start, hold BOOT, press and release RST, then release BOOT.

Questions

Which ESP32-C3-DevKitM-1 pins do I use for the BH1750?

VCC → 3V3, GND → GND, SCL → 9, SDA → 8.

Does the BH1750 work with the ESP32-C3-DevKitM-1 at 3.3 V?

Yes: the BH1750 runs at 3.3-5 V and the ESP32-C3-DevKitM-1 uses 3.3 V signals, so no level shifting is needed.

What is the I2C address of the BH1750?

0x23 or 0x5C. 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 ESP32-C3-DevKitM-1 pinout · GY-302 BH1750 light sensor: all pins and data

The BH1750 on other boards

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

Other parts on the ESP32-C3-DevKitM-1

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