GY-63_MS5611/libraries/ML8511

ML8511

Arduino library for ML8511 UV sensor

Warning

Always take precautions as UV radiation can give sunburn, eye damage and possible other problems. Do not expose yourself to the sun as UV source too long and when using artificial UV light (TL LED etc) use appropriate shielding.

Description

ML8511 - UV sensor - library for Arduino UNO.

Breakout

//      +-------+--+
//  VIN |o      +-+| mounting hole
//  3V3 |o      +-+|
//  GND |o         |
//  OUT |o         |
//   EN |o       S |  Sensor
//      +----------+

Operational

As the sensor / breakout is 3V3 one need to connect to Arduino 3V3. The library converts the analogRead to voltages, and it uses a reference of 5.0 Volt == 1023 steps as default.

If one wants to use other ratio e.g. 3.3 volts == 4095 steps, one can set those with setVoltagePerStep()

    ML8511 light(A0, 7);
    light.setVoltagePerStep(3.3, 4095);

It is possible to always enable the sensor by connecting the EN to 3V3. The value of the enablePin in the constructor should then be ommitted or set to a negative value;

When connecting to an Arduino UNO one can use the 3V3 of the Arduino to power the sensor. However it is not possible to connect the enablepin directly to the sensor. Use a voltage divider (10K + 20K) to convert the 5 Volts to ~3.3 Volts.

Sensor sensitivity

Indoors there is very little UV light so use a known UV source like a blacklight or go outside in the sun.

The formula to convert the ADC reading to mW cm^2 is based upon the graph shown in the datasheet. As I have no reference source to calibrate the library the accuracy is limited. (If you have please contact me)

The sensor has its peak sensitivity ( >80% ) from λ = 300-380 nm with an absolute peak at λ = 365 nm.

Experimental

(use at own risk)

The formula for the experimental estimateDUVindex(power) is based on the following facts / assumptions:

• (fact) The sensor cannot differentiate between wavelengths, so integration with different weights is not possible.
• (assumption) All the UV is radiated at λ = 300 nm. This is the most lethal the sensor can sense > 80%.
• (choice) All the UV is accounted for 100% for the whole value. (Erythemal action spectrum) As we cannot differentiate this is the safest choice.

The DUV index can be used for warning for sunburn etc. Please note that this library is NOT calibrated so USE AT OWN RISK

Table based upon https://en.wikipedia.org/wiki/Ultraviolet_index,

DUV INDEX	Description
0 - 2	LOW
3 - 5	MODERATE
6 - 7	HIGH
8 - 10	VERY HIGH
11+	EXTREME

More about UV

https://en.wikipedia.org/wiki/Ultraviolet_index

Notes

• 3V3 Sensor so do not connect to 5V directly.
• do not forget to connect the EN to either an enablePIN or to 3V3 (constantly enabled).
• library does not work with an external ADC