GY-63_MS5611/libraries/AnalogUVSensor

AnalogUVSensor

Arduino library for analogue UV sensor

Description

Image courtesy Tinytronics

This small (type-less) UV-sensor is powered by 3.3 .. 5 V so it can be used by almost any microprocessor.

The sensor has an analogue output that is roughly linear with the UV-index (sunlight assumed, see notes)

Voltage	UV index
<0.050	0
0.227	1
0.318	2
0.408	3
0.503	4
0.606	5
0.696	6
0.795	7
0.881	8
0.976	9
1.079	10
1.170>	11

From this table the formula is derived (spreadsheet) which is pretty linear between UV 1 and 11.

Notes

Note: The sensor is not calibrated and the table is indicative for sunlight (assumption!) and therefore not suitable for e.g. medical or industrial usage.

Note: UV radiation will not go through glass, so inside you will most likely always read zero. This may help to calibrate the zero level of the sensor.

Note: depending on the light source used, the table above is incorrect. If one wants to use other values one need to fix this in the mv2index() function.

Sensitivity

The sensor is sensitive for wavelengths from 200 - 370 nm, so mostly in UVB and UVA region and less in the UVC.

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

Interface

• AnalogUVSensor() Constructor.
• void begin(uint8_t analogPin, float volts = 5.0, uint16_t maxADC = 1023) set the parameters of the sensor, analogPin, volts and maxADC to specify the internal ADC. Volts and maxADC have a default so these can be omitted.
  Note that one needs to reset these parameters if the settings of the internal ADC are changed e.g. to INTERNAL_1V1 to change the accuracy.
• float read(uint8_t times = 1) Returns the UV index.
  Read the analogue sensor one (or more) times to average the reading. This can improve the accuracy of the reading.
• float mV2index(uint16_t milliVolt) Returns the UV index.
  The conversion formula from milliVolt to the UV index used internally by the read() function.
  This function can also be called with a voltage measured with an external ADC.
• char index2color(float index) Converts an index to the first letter of Green, Yellow, Orange, Red or Purple. Can be used as indication on a user interface.
  This function can also be called with an index from an other UV index sensor.

Power interface

Works only if setPowerPin is called properly.

• void setPowerPin(uint8_t powerPin, bool invert = false) Can be used to control the power of the sensor e.g. for low power mode. Optionally one can set the invert flag to true to invert the HIGH LOW levels e.g. when the analogue sensor is switched through a MOSFET.
• void switchOff() should switch off the power of the sensor.
• void switchOn() should switch on the power of the sensor.

Future

• verify vs calibrated sensor
• investigate angle sensitivity e.g. if the UV light comes from an angle - cosine law.
• investigate response time to stabilize e.g. does it react fast on clouds.
• investigate with different light sources (UVled, TL, sunlight).
• investigate time needed to first (stable) measurement.
• index2time() calculate max exposure time? dangerous?

Sponsor

The development of this library is sponsored by TinyTronics, Netherlands.