Monday, June 3, 2019

AVR ATmega UV meter using ML8511

This device is a UV meter built on top of an ATmega8 microcontroller and a ML8511 UV sensor.
It measures UV light intensity and the UV index.

The ultraviolet index or UV index is an international standard measurement of the strength of sunburn-producing ultraviolet (UV) radiation at a particular place and time. It is a linear scale, with higher values representing a greater risk of sunburn. The purpose of the UV Index is to help people effectively protect themselves from UV radiation.

It features an LCD display that shows you all the measurements, a temperature sensor to correlate the output against temperature too, the UV led is attached to this meter makes this device particularly suitable to test glass UV lens. It also works with a 9V battery.
The LCD displays UV light intensity in mW/cm2, UV index, current temperatore, a light intensity offset, that this the difference from two values of UV, and the UV wavelength measured.
The light intensity offset is usefull to measure the real UV intensity reduction of a lens for example.
In my case the UV led mounted is a 3W@365nm, so I set the wavelength to 365, but one can change it using the menu that is accessible by long pressing the Select button.

For further information on the sensor library please take a look at my blog post here:


  • read risk disclaimer
  • excuse my bad english