Analog input problem

Hi, my Arduino Duemilanove analog input is returning numbers around 400 without anything turned on. What do you thing about it? Can it be problem of Arduino?

Thanks!!

Daniel_DSO: Hi, my Arduino Duemilanove analog input is returning numbers around 400 without anything turned on. What do you thing about it? Can it be problem of Arduino?

Thanks!!

A analog input pin with nothing wired to it will have a 'floating input pin' condition and will give random/noisy/meaningless values if read from. If you want to test a analog input pin first wire to a ground pin and perform a analogRead and see the value returned, then wire the pin to 5V pin and test again and see the reading.

Lefty

As I write this, my Arduino web server is publishing the values of analog pins 2-5. Only pin 5 is actually measuring anything, and is varying according to a sensor. Pins 2, 3 and 4 are floating: as you'll see if you click the link, not only do they change, they're quite different to each other.

Thanks so much retrolefty and JimboZA!!! Now, it's working.