My application is: detect day versus night, indoors, in a room with south facing windows. I am exploring the Si1133 to measure UVA. I can put the detector within 10 feet of the windows, high and facing down so the detector gets reflected UV, and never gets direct sunlight, and gets only reflected artificial lights from typical room lighting of about 400 lux white, fluorescent light. My understanding is the window glass will transmit about 50% of UVA, that the sky will scatter significant UVA, that night sky has no UVA, and that artificial lights produce negligible UVA.
Might that work? Do you have any suggestions re diffuser, physical filters, parameters of the Si1133, and which set of diodes to use? My plan is to read only the UV diode.
I want to estimate sun time by detecting sundown and sunset, despite noise from artificial lights. I don't need accuracy. I plan to take samples over many days. I understand that the weather and season will have an effect.
More info. I found that the measurements are very low, in the range of -5 to 30, very roughly speaking, with the HW_GAIN set at 11 (0xb), reading the UV diode.
If my code decides that a measurement over 6 is daylight, then the sensor only detects daylight when the sensor is within about three feet of a south facing window, with the sensor pointed towards the window, and with a piece of PTFE plumbing tape against the sensor as a diffuser. I was hoping for a better result, since I want to place the sensor farther from the window, and facing down from the ceiling, in a typical household room. As it is, it would only work if the room was a sunroom or greenhouse, with significantly more windows than a typical room.
That sounds quite challenging as the sensor is not used for those type of applications. In fact, it's required to place the sensor facing upwards for UV measurements. You have to put a diffuser on top of the sensor as well.
UV reading should be close to 0 (-5 to 5) in an indoor environment and at night. You can record a few days' data and see how much UV light you can receive coming through the window at daytime using our Si1153/33-OPT-EXP board. We have a reference design on that board. You can use the configuration for UV(diffuser) design in our software tools Si115x Programmer's Toolkit in your test.
As far as detecting sunset vs sunrise, I don't think the sensor will be able to do that.
I wish this could solve your problem here: https://electronics.stackexchange.com/questions/388241/sensor-to-distinguish-between-daylight-and-artificial-light-in-a-room
Heya..Thanks for ur valuable Post.
The Si1133 is a UV Index Sensor and Ambient Light Sensor with I2C digital.Wearables ,Handsets , Display backlighting control and Consumer electronics .These are the application that i know from :Viva tv
That sounds really good.
The UV light increased directly from sun.But the Home light didn't increased from sun.The UV light Is dark blue in colour but the home light Is not dark blue in colour.So it is better to use Schotty diode to rectify this.
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