When i connect arduino ground to a 2V point in another circuit (the circuit is powered by 5V), the ground and Vcc are shifted up by 2V and the adc readings get messed up, but i don't get it? Shouldn't the adc still measure corrrect voltage...since it measures with respect to arduino ground?..but this is not happening with my case...I suspect the usb device is affected by this voltage shifting? ....a bit confused here ![Frown :( :(](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)