Hello fellow Arduino-lovers, I wanted to do some light measurements and as I had no photodiodes lying around (except some old CNY-70s) I decided to use a LED, (which should be possible in general, right?) when something weird happened.
The results on my Arduino Mega 2560 look like this:
I connected the LED like this:
With the cathode to GND, just as it should be. And a 82k current limiting resistor, which might be little to high, but that is another problem. If I turn the LED by 180° (cathode to 5V) it looks just the same, but with higher peaks.
If somebody can tell me why:
- I can't read out proper values of the 'photodiode'
or even more important:
- Why it makes these interesting curves
that'd be great.
It looks somewhat like charging and decharging a capcaitor to me.
Greetings and thanks in Advance :)