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FunHouse: Light leakage from backlight to sensor
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FunHouse: Light leakage from backlight to sensor

by wminarik on Fri May 14, 2021 3:13 pm

The backlight from the FunHouse display leaks into the ALS PT19 light sensor (funhouse.peripherals.light). I've attached a plot with the raw readings. This can be remedied with some opaque tape (I used electrical) applied to the side of the display (photo attached). There's a tiny bit of leakage also from the red LED, but it's almost in the noise.
BackLight_Contamination.png
plot of ADC from the light sensor with the backlight off and on
BackLight_Contamination.png (47.24 KiB) Viewed 335 times

FunHouse_LIghtBlock.JPG
black tape covering the display edge
FunHouse_LIghtBlock.JPG (268.27 KiB) Viewed 335 times

wminarik
 
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Re: FunHouse: Light leakage from backlight to sensor

by johnpark on Mon May 17, 2021 1:19 pm

Thanks for the great tip, I've added this info an a link to your post in the main FunHouse guide.

johnpark
 
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Joined: Wed Mar 25, 2009 2:15 pm

Re: FunHouse: Light leakage from backlight to sensor

by zvonler on Sun May 30, 2021 9:47 pm

wminarik, could you post the code you are using to read the light sensor on the FunHouse? I have two of the boards, and the demo sketch shipped on each was able to sense and display different light levels, but every sketch I've tried to load since only gets zero from the analogRead call. I even tried the sketch from https://learn.adafruit.com/adafruit-fun ... st-example and it also shows only zero for the Light value.

zvonler
 
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Please be positive and constructive with your questions and comments.