# Bolt LDR SENSOR

Hello Sir
What is the voltage of A0 pin of wifi module when nothing is connected to it.??
Is A0 pin a GPIO pin or just an input pin??

In the first project using LDR Sensor , in what format does the LDR read the value??
Can you please explain me sir??

HI, First of all you should know in Bolt module A0 is a ADC pin (Analog to Digital Converter) and it can read between 0v to 1v range. GPIO pins are 0,1,2,3,4.
LDR reads the value in an analog electrical signals and then A0 converts it into digital.

@akhil.raibhog I didnâ€™t get you.
Digital means just zeroes and ones , how is the value 1.02 thousand a digital value??

LDR is giving reading in terms of voltage. such as V=(5XR1)/(R1+R2) where R1 is fixed resistor we connected-10K and R2 is LDR resistor.
Suppose if bright light is there, then Resistor R2 is less so voltage will come as 1.02 thousand and when light is less, Resistance R2 is more and voltage is some very less voltage. Hope it will clear your doubt @chakitbhandari93

The A0 pin on bolt collects the junction voltage of the LDR, converts it into digital signal, and sends it to the cloud.

When you are viewing the voltage data, the value stored in the cloud is retrieved by the computer and converted to decimal format, which then appears on the screen.

The A0 pin sends 10-bit data i.e. 2^10 = 1024 values. So the reading of A0 pin (scaled up by 1000 times) can range from 0 - 1024. So the value 1.02 thousand is actually 1024 i.e. 10th power of 2.

Hope this helps.

Thank you so much @b.utkarsh