The D09 (D10/D11) datasheet on page 150, section 18.104.22.168 ("User Control of the Voltage Reference System"), says:
To enable the temperature sensor, write a one the Temperature Sensor Enable bit (VREF.TSEN) in the VREF register. The temperature sensor can be redirected to the ADC for conversion. The Bandgap Reference Voltage Generator output can also be routed to the ADC if the Bandgap Output Enable bit (VREF.BGOUTEN) in the VREF register is set. The Bandgap Reference Voltage Generator output level is determined by the CALIB bit group (VREF.CALIB) value in the VREF register.The default calibration value can be overridden by the user by writing to the CALIB bit group.
I can't find the VREF register. There is nothing in adc.h. The BGOUTEN and TSEN fields are also a dead end.
When I read the 1V reference anyway, the values are those of an unconnected pin, ex: 1843, 1565, 2072, 1575, 2063, 2085, 1577, 1847, 2083, 2089, 2106, 2025, 2090, etc.
I did find: http://atmel.force.com/support/a...
Did I overlook something??