Digital Light Meter

About this project

Build a handheld precision lux meter using the TSL2561 digital light sensor — the same class of sensor used in professional photography light meters and building illuminance audits. Unlike a simple LDR that gives a rough analog reading, the TSL2561 contains two separate photodiodes (visible+infrared, and infrared-only) and does the sensor math internally, returning a calibrated lux value over I2C that's accurate across an enormous 0.1 to 40,000 lux range — from a dark room to direct sunlight — without any manual calibration. A 16x2 LCD shows the live lux reading plus a plain-language brightness category (Dark / Dim / Indoor / Bright / Sunlight). The WOW moment: point it at a phone screen, a tube light, and a window, and watch genuinely accurate numbers that match a real lux meter app. Build time: 2 hours. Fully offline.

What you get

• Complete, commented source code
• Full components list with quantities
• Pin-by-pin wiring guide and connection table
• Step-by-step upload and testing guide
• Project report (.docx, IEEE style)
• Presentation slides (.pptx)