Analog read problems

Forum 2005-2010 (read only) Hardware Troubleshooting
1

I will begin by saying I am new to arduino. I bought a shield for photography (Loading...). It work fine for about a day then the buttons stopped working. The buttons are wired in series to resistors so that 5 buttons would create 5 different analog values for one analog input. I began reading the basic tutorial for beginners and did a analogRead() and Serial.println(). The serial monitor show a constant stream of 1023. This is the same with all of the analog pins. I plugged a 10k pot and it still doesn't change. Is the chip or board broken or and I doing something wrong?

Thanks,
Matt

2

What is the code you are using? What happens if you use a different analog input?

3

Remove the shield.

Connect the analog input to GND. Do you get a rock-solid zero from analogRead?

Connect the analog input to +5 V. Do you get a rock-solid 1023 from analogRead?

4

I am using the code from http://arduino.cc/en/Tutorial/AnalogReadSerial

When I connect the analog input into GND, it still reads 1023.

5

What about analog input 1? What does it read when connect to GND?

6

I have tried connect all of the analog ports to ground and they all read 1023.

7

If the chip is socketed, try re-seating it.
Are you sure you connected it to ground?
Maybe the ADC happened to die due to bad luck?

8

I tried reseating the chip.
I tried connecting the analog to all of the GND pins on the board.
If it is an ADC problem, do I have to replace the chip or the board? Are there ways to to be certain that the ADC is the source of the problem?

9

Are you using the ports on the side with the 9V input socket? And what board are you using?

10

I have an arduino duemilanove.

On this reference picture, http://www.satistronics.com/arduino-duemilanove-2009-pcb-board_p2765.html , I have a connector between GND below the power pins, and 0 below the Analog IN pins.

11

What analog readings do you get with nothing connected?

Are you using version 0022 of the IDE?

12

I am using 022 and I always get 1023, unplugged or not.

13

If this...

...is really what you're using for testing then I'm afraid the only thing left is a damaged A/D converter. If that is the only problem (and it sounds as though it is), you can replace the processor. Be sure to get one with a bootloader (or be prepared to install a bootloader).

14

So I just need to replace the Atmega chip and not the board. Correct?

15

Yes.
It has to have a bootloader though.

16

Ok. Thanks for all of the help.