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Posts: 2
Registered: ‎07-15-2015
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UV Index Reading for Si1145

I am using Si1145 for UV index, but the value is very sensitive. From my desk to window, 2m in distance, the reading value from (REG_AUX_DATA1, REG_AUX_DATA0) changes from tens to more than 2 thousands. (corresponding uv index is 0 to 23 if I don't constraint the max by 11).

I also test Silab EVB, which is using Si1146. The EVB doesn't have the same problem.

I leave most of parameter ram values in defult. I only change CHLIST(addr 0x01) to 0x80 (EVB sets to 0x83) and ALSIR_ADC_MISC (addr 0x1f) to 0x20 (EVB sets the same value).

 

I also read back all the register values and parameter ram valuses from sensor is attached in the spread sheet.

Can you give some clue about the problem?

Any suggestions are appreciated.

Thanks

 

 

Posts: 327
Registered: ‎09-22-2009

Re: UV Index Reading for Si1145

Please refer to Section 2.4 of the datasheet where it explains set up of the device. You must set the VIS_RANGE and IR_RANGE bits for UV measurements.

 

http://www.silabs.com/Support%20Documents/TechnicalDocs/Si1145-46-47.pdf

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Posts: 2
Registered: ‎07-15-2015

Re: UV Index Reading for Si1145

Hi, Alan_S,

 

Thanks your suggestion it solved my problem.

Jack