Using Mega analog input features

ATMega 1280 has analog input features that do not seem to be supported by the Arduino software compiler. These are (for example) differential inputs, more than one internal reference voltage. Is there any way I can access these features. I am new to Arduino and do not understand all the acronyms so please keep answer simple, however I do have programming experience including assembler. Thank you.

You can access the processor at levels below the abstraction of the Arduino development environment. For example, you can use the API's provided by the AVR-LIBC library (which the Arduino itself uses internally):

http://www.nongnu.org/avr-libc/user-manual/index.html

And of course, you'll have to dig in to the ATmega1280 datasheet from Atmel.

You'll also have to be careful to not get stepped on by Arduino functions. Timer 2 is used for the tone() function for example. Looking through the core Arduino firmware files (wiring_analog.c) is a good tutorial.

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