reference voltage

Hi all

I noticed that for when you using most of microcontrollers measuring voltage from Voltage transfomer and reference voltage of 2.5V is used/added to VT , is possible using the 5V the arduino provides and use voltage division to get 2.5V you need? if possible do u need to code/program the arduino to give you this 5V or u just measure it direct on the 5V pins after being switched on ?

I don't understand what you mean :-(

Have you been looking for a forum section of your native language?

The voltage on output pins equals the operating voltage (Vcc), typically 5V or 3.3V. If some external device expects lower logic input voltage, a voltage divider can be used on the digital output pins.

Since the input pins do not allow for negative or AC voltages, an offset voltage has to be added to such signals, so that these are in the range of 0V to Vcc.