LTR303 Library

The LTR303 Library provides a simple and easy-to-use interface for integrating the LTR303 ambient light sensor into your Arduino project. This compact and low-cost sensor measures the surrounding light intensity, making it suitable for a wide range of applications such as home automation, robotics, and IoT projects.

With its small size (2.0mm x 2.0mm x 0.7mm) and low power consumption (220uA active supply current), the LTR303 is an attractive option for projects that require a lightweight and energy-efficient solution. The sensor features a I2C interface with a fast mode of 400kbit/s, making it quick to communicate with your Arduino board.

The LTR303 also boasts several features, including built-in temperature compensation, immunity to IR/UV light sources, and automatic rejection of 50/60Hz flicker. With a dynamic range from 0.01 lux to 64k lux and 16-bit effective resolution, this sensor is capable of providing fairly accurate and precise measurements, however it is not suitable for precise lux measurements; for that use case, consider the VEML7700 sensor.

Library Features

• Supports multiple I2C buses
• Option to auto-adjust the gain setting during operation
• Includes doxygen comments for all public functions
• Returns error codes for easier debugging
• Provides the isConnected() function to check the sensor connection status

Warnings

• Only tested with the ESP32 and ESP32S2 (but should work with all arduino boards)
• Interrupt based triggers not implemented

Setup

#include "ltr303.h"

LTR303 lightSensor;
double lux = 0.0;

Wire.begin();
lightSensor.begin(GAIN_48X, EXPOSURE_400ms, true, Wire);
lightSensor.startPeriodicMeasurement();

Loop

if(lightSensor.getApproximateLux(lux)){
Serial.printf("%8.4f,\n\r", lux);
}
delay(1000);

Verify Correct Sensor Connection

This function checks for the correct I2C response, manufacturer ID, and part ID. It prints a human-readable error report to the provided interface stream (Serial by default) and returns true if the device is correctly connected; otherwise, it returns false.

if (lightSensor.isConnected(Wire, &Serial) == true) {}

Schematic

• The library has been tested at 400khz (for over a year) with the ESP32 using internal pullups with no errors.

Acknowledgements

This library is based on the original work of Lovelesh Patel in 2015. You can find the original repository at https://github.com/automote/LTR303.

To support my work, consider visiting my store at https://keastudios.co.nz/.