200ohms potenciometer as analog input, Arduino UNO

Grumpy_Mike:

fofro:
I believe that the A0 pin's impedance is too small, giving a different voltage value on the wiper terminal. It needs to be a very high value in order to read voltage like a voltmeter does...

Anyone knows the A0-A5 pin's impedance? And if it's tunable?

It is nothing to do with the impedance. It is very high and connecting a low impedance to it will not affect the reading.
Why do you use the a.analogueRead and not just analogueRead?

Maybe it hasnt but I think it does. I use a.analogRead bc im using matlab instead of Ide environment...