Leonardo and interrnal 2,56v Aref - not ok according to Arduino 1.5.8beta

This line, gives:

 analogReference(INTERNAL2V56);

BatteryTester.ino: In function 'void setup()':
BatteryTester.ino:95:18: error: 'INTERNAL2V56' was not declared in this scope
Error compiling.

But the chip does provide 2,56V Aref.

Not supported, according to the documentation:

Just use "INTERNAL" - there's no other option, so it makes no sense to specify the voltage.

32u4 referance says:
"Optionally, AVCC or an internal 2.56V reference voltage may be con-
nected to the AREF pin by writing to the REFSn bits in the ADMUX Register. "

So which one is the one Arduino limits me to ? - does it use VCC or 2.56 ? (I assume the VCC)

  • so can I inject some assembly to set ADMUX properly ?
    I need REFS0 and REFS1 (bit 6 & 7) to both be high in ADMUX

I am not seing the assembly produced, but adding this should work, right ?
ADMUX= (1<<REFS1) | (1<<REFS0);

And “no” - somehow this does not have any effect, Vref is still 5V