LilyPad voltage refence of ADC of 3.3V

Using Arduino Project Guidance
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I am feeding the LilyPad with a power supply (LilyPad Power Supply - DEV-08466 - SparkFun Electronics) so it should supply a Vcc of 5V. However, I believe I am getting 3.3V, because I have connected a temperature sensor, and I get the correct read of temperature in degrees when I suppose that the voltage reference of de ADC is 3.3V doing that:

read = read * (3.3/1024.0); //and I get ~22ºC (correct).

If I write: read = read * (5.0/1024.0), I get ~60ºC (degrees). It is not correct, although it should be. Why?

Thanks!

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Probably time to measure the voltage with a good digital meter.

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Check what the voltage is at the AREF pin. If it is 3.3V then your reference is 3.3V.

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