gaining accurate time on time sensitive measurements.

Projects General Guidance
16

ref = analogRead(14) reads Analog pin 0 - that should give you a value between 0 and 1023

if you connect GND to A0 ==> you should read 0
if you connect 5V to A0 ==> you should get 1023

The right formula is

Voltage = 5.0 * ref / 1023; // there is always discussion if this should be 1023 or 1024, in practice the diff is less than the noise

Only if you set the - analogReference() - Arduino Reference - to 1.1 volt the formula should be

Voltage = 1.1 * ref / 1023;

in terms of code // use spaces and empty lines to improve readability

int ref;
float Vin;

void setup()
{
  Serial.begin(9600);  // you can use 115200 12x faster!
  delay(1000);
}
void loop()
{
  ref = analogRead(14);   // or A0
  Vin = 5.0 * ref / 1023;

  Serial.print(Vin);
  Serial.print(",");
  Serial.println(ref);

  delay(100);
}