Many times I thought of a system that will track a sensor readings for specific time and save that data for future analysis after doing the same task for several days. So I made a system using Arduino and the amazing 1sheeld to save LDR readings in an Excel sheet and that is what we are going to do now.
LDR is an acronym for "light dependent resistor" as it's a resistance but its value changed with light in the environment. 1Sheeld is a platform for Arduino that allows you to tap into your smartphone's sensors and capabilities and lets you use them in your Arduino projects.
Basically, 1Sheeld is a hardware shield that sits on top of your Arduino board and communicates over Bluetooth to this Android app, to transfer data between it and your smartphone.