Light Depedent Sensor(Reading Issue)

Problem: The LDR Sensor is only giving Reading of 1.02 Thousand Everytime,
Not been Able to Figure out what is actually going wrong?
All connections have been done Properly as Specified
1.5V/3.3v connected to LDR Leg and resistor Leg
2.A0 Pin to LDR.
3.Ground to Resistor

Due to different internal resistance of LDR you are getting reading of 1.02 thousand with 10k Ohm resistor
Try 330 ohm resistor (Orange Orange Brown) instead of 10k ohm resistor

Turn off the light and check the value. It will give different value as when there is light, only that time it shows 1.02 thousands. Check the result in dark once, you will get different value.

I faced the same issue. If you have a multimeter then check the components once, especially the ldr. Also clean the legs of the components. Even though they are new, sometimes because of oxide layer the working of the components might get hampered. I just did these steps, and reassembled the circuit, and it worked.

Don’t use much wires and all just keep it simple and attach it directly to the bolt cloud a0 pin etc.
And press the deploy configuration tab frequently in 10 sec so you will get variety of readings


Well hello everybody, I hope this issue stands resolved. But, there is something else you should know. At the risk of sounding crude, I feel this plant & light monitoring project has 1 inherent shortcoming. This arises due to 2 reasons :

  1. The A0 pin can only read from 0 to 1V (or 0 to 1023, as per the 10 bit inbuilt scaling)
  2. The LDR internal resistance is highly nonlinear in relation to the perceived light intensity.

Now, coming to the issue you raised (to which I believe the circuit connections are correct), the A0 would read 1.02 thousand, regardless of whether the LDR is brightly illuminated or just sitting in some corner of your house receiving indirect sunlight.

In the figure I attached, R is the LDR resistance. This varies exponentially with light level, which leads to the A0 pin saturating at 1023 even at moderate light levels. But, in poorly lit situations, you can see the difference. A0 then, will be a value less than 1023 (or 1.02 thousand so as to be precise). Now, this is where the problem lies for plants. With no distinction between moderate and bright light, Plant monitoring hits the roadblock, as far as this project is to be concerned. The values of R (as per the lighting conditions) used in the attached figure are tentative for the model of LDR used here.

One solution for this : Use a voltage divider (using a resistive divider) to further scale down the 3.3V supply so that the entire range of LDR voltage variation is captured in the 0 to 1V voltage range of A0. Ofcourse, you would possibly need resistance values not provided in the hardware kit.

Good day.

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