I’m trying to use a anlog pin (A0) to read the values from a potentiometer. I’m using the “Video Frame Capture” sketch, but if I turn the potentiometer on A0 the brightness threshold changes. Is this normal? Is possible to read analog pins using the “video frame capture” sketch?
I’m afraid you can’t use other analog pins when doing input processing with the Video Experimenter. The analog to digitial converter (ADC) of the chip needs to be disabled in order to use it for the brightness threshold. It’s a limitation of the ATmega328.
You can use analog pins when generating video signals and overlay, but not when capturing video input.
If you are interested in the details, see section 22.2 “Analog Comparator Multiplexed Input” in the ATmega328 datasheet.