BH1750 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>
#include <BH1750.h>

const int SDA_PIN = 8, SCL_PIN = 9;   // use your board's I2C pins
BH1750 light(0x23);

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);
  if (!light.begin(BH1750::CONTINUOUS_HIGH_RES_MODE, 0x23, &Wire)) {
    Serial.println("BH1750 not found: check wiring or try 0x5C");
    while (true) delay(1000);
  }
}

void loop() {
  Serial.printf("%.1f lx\n", light.readLightLevel());
  delay(1000);
}

Needs the BH1750 library. 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

LCD Ultra Pro has this sensor as a built-in value source. Choose it in a rule, and a label or gauge shows the reading without writing code.

Boards with a ready connector

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

Good to know

• The ADDR pin selects 0x23 or 0x5C.
• Keep it away from the backlight when used for auto-brightness.
• A window or diffuser in front changes the reading.

What it is good for

• Automatic display brightness
• Grow light monitors
• Daylight-based switching

FAQ

Sources

• https://wemos-docs.readthedocs.io/en/latest/_static/files/bh1750fvi-tr.pdf

Related parts

• BME280
• INA219