Hello! I am building a project, and now I need to get the temperature by a temperature sensor, but I have fluctuation of the power supply (AAA battery), so I cant get the temperature in degrees if I can't know the voltage reference of de adc (Vcc). How can I know this voltage? I am using an Arduino LilyPad, so I cantt use AREF pin because I think it has the AREF pin join to the Vcc externa (I am not sure about this). Thanks!
What temperature sensor are you using? Many do not require a fixed reference voltage.
By measuring the internal voltage reference you can make a correction and find out what your real supply voltage is.
I am using the MCP9700 temperature sensor (LilyPad Temperature Sensor - DEV-08777 - SparkFun Electronics). Could you show me how can I use this internal reference? Thanks!