Actually I am working on a LDR robot and taking inputs from analog pins pm Arduino motor shield R3,I found values lying mostly between 0 to 100. When I checked all the analog pins without any LDR sensor connected to arduino I saw values like 500 on almost all the pins (A0 to A5).
I am frustated and find no solutions.I doubt if this is because of noise in the motor shield circuitry as the arduino uno R3 alone does not show such happenings.
Please help?????????/
Does that mean you're measuring the analog inputs without anything connected? In this case you're measuring a floating pin which gives you a quite random reading. If you want to have a zero reading connect the analog input to GND and read again.
When I checked all the analog pins without any LDR sensor connected to arduino I saw values like 500 on almost all the pins (A0 to A5).
The answer is to never leave an input unconnected it will pick up noise.
I am frustated and find no solutions.
The answer is power supply decoupling:-
http://www.thebox.myzen.co.uk/Tutorial/De-coupling.html
And maybe the odd capacitor across the analogue input.
somanshumehta:
I understand the use of power supply decoupling,but across which chip should I place a ceramic capacitor and of what value?
Accross every chip and 0.1uF
Currently I am using a UNO R3 and when I check my analog input pins through serial monitor,all the pins A0 to A5 shows values between 252 to 350 without connecting any sensors or any voltage into it.I checked it several times with simple analogRead() function.
Why is this happening? Any Idea!!!Lol
all the pins A0 to A5 shows values between 252 to 350 without connecting any sensors or any voltage into it.
Yes they will. This is called a floating input and it applies to analogue or digital input pins. They have to be connected to something.
How are you wiring the LDR sensors up. They need a pull up or pull down resistor as well as the sensor, what values are you using?
Try connecting a 0.1uF ceramic capacitor from the analogue input to ground.