No resistance between analog in and ground

I think I may have blown my ATMega 328 in my Duemilanove but I don't have a second one to verify.

Everything on my prototype breadboard works fine until I attach it to my Arduino. Then a bunch of voltages on my analog inputs drop to zero when they shouldn't - it appears as though they are somehow grounded.

So I removed everything and checked the resistance on my Arduino between my Analog input pins and the ground, and it is showing a resistance (varies from 200 Ohms to 4kOhms depending on which analog pin I am using).

I would have expected that there is normally no path between analog inputs and ground. Is this right, or am I just going crazy?

Would this indicate a blown ATMega 328?

Any help would be great.

Brian

I would have expected that there is normally no path between analog inputs and ground.

Measuring the resistance between pins of an unpowerd device tells you very little. Most pins will look like diodes.

It could be you have a fault but equally it could be your code is defining those pins as outputs with a logic zero on them.

OK, but with the analog pins you can't specify them as output can you?

bpmccain: OK, but with the analog pins you can't specify them as output can you?

Yeah you can - they are digital 14-19

Wait a minute.. I'm confused.

You are reading Resistance with ?? A small LCD type meter??

The Arduino is powered OFF?? You can't measure resistance with voltages being sourced by the equipment...

You will probably find the the resistance reading is quite different depending on which polarity you connect the meter leads: it sources a voltage to measure resistance... The analog pins are BOTH Digital and Analog and have several FETs connected to the pin.

I have a test shield that tests all the digital and analog pins for both High and Low drive capability, and that the analog inputs can read 3 different voltage accurately. It's 19 resistors on a protoboard... But it MIGHT be worth having.. The info and code is here: http://terryking.us/arduino-testing.htm

It puts results out to the Serial Monitor.

If a pin is seriously damaged and leaky, all the tests will fail.

Let us know how you make out....