Another wireless UV Radiation Meter

In the last post, ( 30 September 2020 ), I described my UV radiation meter. That version had Bluetooth (BLE) enabled. Since then I have made a second * version of the meter, but this time having WiFi functionality instead. It is based on the same hardware ( SI1145 sensor & Heltec WiFi Kit 32 module ) as before. As the WiFi Kit 32 module ( see 02 August 2020 ) has both integrated Bluetooth and WiFi, the only changes needed have been to the firmware. I have used an identical enclosure; so the physical appearance is also the same. However, different information is now being displayed on the OLED display.

In use, WiFi typically has a communication range greater than BLE. The meter can be configured either as a Client station connected to an existing network's WiFi router, or as a stand-alone WiFi Access Point; the latter being the more suitable for outdoor use. The meter hosts a web-server, so that a web-page with the UV index measurement can be displayed by connecting to its IP address using a browser on a pc, smart phone, or other WiFi enabled devices etc.

 

A simulated reading displayed on a smart phone

The image above shows the UV Index measurement displayed in a browser. I should point out that the reading was made under controlled laboratory conditions during testing. A background UV Index reading made in an indoor environment would typically be about 0.02 !  

I am calling it the "Spacer-Labs" UV radiation sensor after the location of my laboratory.

* Actually I have also made a third version without any wireless connectivity at all.      

UV Radiation Meter

Frequent or prolonged exposure to high levels of solar ultra-violet (UV) radiation can damage the skin. But how can we know exactly what that level is ?

I've designed a UV Radiation Meter to measure and display ultra-violet light radiation from the sun. It will be useful to quantify what UV radiation level I am actually exposed to when outside, particularly in summer, though I do normally take the precaution of at least wearing reactive spectacles and a hat.

The meter is based on the Silicon Labs SI1145 UV Index sensor, ( with I2C interface - see 27 March 2019 ), and the Heltec WiFi Kit 32 (HTIT-WB32) ESP32 development board with blue OLED display which I featured in the last post. It has an internal 3.7V 1000mAh Lithium battery which gives about 17.5 hours of continuous operation, and can be recharged in-situ by USB; charging time 3 hours 40 mins. I chose a stylish white hand-held enclosure; it looks quite smart.

UV Index, ( zero to 11+ ), and UV Level are displayed according to the W.H.O. definitions; Low, Moderate, High, Very High & Extreme.

UV meter displaying an indoor measurement

In the image above, access to the micro usb connector for battery charging and programming is on the left.

I completed it too late for using it much this year; but it's ready and waiting for next summer.

( W.H.O = World Health Organisation )