Output values of light monitoring system project

what is the meaning of these values ? (Please see screenshot) means after kipping hand on LDR values are less in number and after removing of hand from LDR value comes in thousand.(What is the unit of these values?)
and also we have to keep the bolt iot wi fi module always connected(by usb cable) to laptop or smartphone.Why it does not connect directly(wireless) to hotspot of smartphone?

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You are connecting a voltage division circuit to the ADC pin(A0) of the Bolt IoT module. The resistance of LDR decreases as the intensity of incident light on it increases. This causes a change in voltage at the ADC pin. The ADC converts this voltage to a corresponding integer(digital) value and that is what you are observing on the screen. Higher the number indicates higher intensity of light which reduces the LDR resistance and hence increases the voltage at the ADC pin. Vadc=V*R1/(R2+Rldr).
The Bolt IoT module has a 10bit ADC, meaning it can read upto 2^10=1024 values(levels). This gives the range of (0-1023).
You need to power on the Bolt module to have it connected to your WiFi network. This can be done through the USB port of your computer/mobile or from a suitable charger.

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Means,if i plugged a charger instead of laptop or smartphone, it will work.Thanks for your reply.

So in the project you are connecting the voltage divider circuit to input A0 pin. The resistance of LDR decreases with increase in intensity of light. So voltage of input A0 signal also increases. ADC converts this voltage in to integer. As higher the value of integer higher the voltage of input a0signal. Hence lower the value of resistance of LDR. Bolt Iot has 10 bit digital value read upto 2^10 values.

I think it’s Vadc=V*R1/(R1+Rldr). right? and also if LDR resister is decreases then Vadc should also decrease cause V=IR. If I’m wrong can you plz explain.

Your Vadc expression is right but if you see in the expression, LDR resistance is in denominator so increase in LDR resistance leads to decrease in Vadc. Vadc is the voltage across R1 resistance .

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Okay I got it now. Thank you :blush:

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