Arduino-Digital Light Meter

Project Summary

A light meter is a very useful device that finds applications in hospitals, schools, factories, parking lots, passageways, and many more to measure and maintain adequate lighting levels. It is also useful in photography to set an accurate exposure for the camera. This project describes a simple Arduino-based digital light meter, which is capable of measuring the ambient light intensity ranging from 0-65535 Lux. The output is displayed in both Lux and Footcandles.

Project Description

Hardware The BH1750FVI sensor is used to measure the incident light intensity. BH1750FVI is a digital light sensor IC that directly provides calibrated output in Lux. It can measure ambient light intensity ranging from 0 to 65535 Lux. The sensor output can be accessed through an I2C interface. For displaying the result, a MAX7219-based serial 8-digit seven segment LED module is used. MAX7219 allows you to control 8 common cathode seven segment LED displays with only 3 I/O pins from a microcontroller. Figure 1 shows the wiring of the sensor and the display module to the Arduino board.

Figure 1  Arduino connections

A tact switch connected to Pin 2 of Arduino operates in interrupt mode and is used to toggle the output between Lux and Footcandles. The complete project setup is shown in Figure 2. The sensor and tact switch are soldered on a general-purpose prototyping board, which plugs onto the Arduino Uno using male headers. Using a proto-shield would be much easier to build the hardware of this project.

Figure 2  Complete setup of the project

Software The LedControl library is used to interface the MAX7219-driven seven segment LED display module to Arduino. The sensor data is read using the Wire library. The sensor is configured for a measurement resolution of 1 Lux. The measurement and output display are both refreshed every second. Click here to download the full Arduino Sketch
Output
The sensor should be faced directly toward the light source that is to be measured. The default unit of display is Lux. Press the Mode switch to toggle between Lux and Footcandle units. Figure 3 shows the light meter displaying output in Footcandles (Fc).

Figure 3  Digital light meter in action

More details can be found at the Author’s personal page.

تصنيف :