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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!!
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Left Coast, CA (USA)
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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
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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.
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Retired from Arduino.
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Thanks so much retrolefty and JimboZA!!! Now, it's working.
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