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So strong jumps I could not determine with me yet, here only a log (only few seconds) as with me fluctuates. |
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These are my values right now (I logged the A0-Pin readings in order to be as close to the hardware as possible).
However, all this does not happen as soon as I replace the LDR with a constant 1k resistor. In this case, the readings remain absolutely constant. Next steps, as mentioned before:
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@hamster65: I forgot to mention: I removed the connection to the matrix and unplugged the temperature sensor. So, voltage should be stable. My (cheap) multimeter permanently shows either 3.33V oder 3.34V on the LDR pins (measured with the LDR, of course). |
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It's interesting that a 1k resistor gives constant readings. What resistance value is the LDR under normal light conditions? Maybe the impedance is too high for the ADC and a buffer is required? But this would not explain the volatiliy. |
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Hi, a lot of insights:
At this point, it looked like some types of LED lights seem to brighten and darken. But as this could be observed with different lights (some of them usually been used in object lighting), and as I couldn't visually observe it by myself, I procured some lux meter device. I learnt: values will be jumping around by some percent with these LED ceiling lights, but the range still was not as big as the range of the LDR readings. This instability only partially explains the phenomenon. So I dug further and learnt about our visual spectum. Obviously, LED lights sometimes change brightness in wave lengths we don't notice at all. However, LDRs sometimes can be sensitive to wave lengths which can't be observed by human eyes. Sensors like BH1750 or OPT3004 mimic the visual experience of the human eye - and they deliver real lux values! I bought a BH1750, connected it to my PixelIt, and was able to observe minor instabilities which were perfectly in range with those of the lux meter device. A PR with BH1750 has been provided. ==> Case closed. |
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The readings of my LDR are jumping a lot. I dug into the library and had a look at the original values on the A0 pin of my ESP8266.
They keep going up and down: from 380 slowly raising to 430, then dropping to 310, raising again to 380, staying stable for some seconds, then starting the whole procedure again.
Smoothing helps a bit (feature yet to be coming for PixelIt).
Replacing the LDR by a second one of the same type (GL5528) didn't help => obviously the LDR isn't broken.
Replacing the LDR with a constant resistor lead to constant values => obviously, the A0 pin is working correctly, it is not a hardware issue with the ESP8266 or power supply.
Next, I will replace the "pullup resistor" (currently 1K) with a a 10K resistor. Expectation: readings will still jump, but the range will be smaller.
Does anyone else experience this kind of volatility?
I also checked various sources of light:
Seems any kind of 50Hz lighting leads to trouble, but I don't know why.
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