AVR-Chat

Hi
Is it possible to use the ADC input to sense the supply voltage and
automatically drive a spare output connected across the reset pin to
zero when the supply sank to say 4 volts and thus act as a brownout
detector? 
If you had a diode to a big enough capacitor for the microcontroller
supply, the voltage would only fade slowly and I would think you would
only need to poll the adc every half second or so.
You might have to enable this only after the ADC was initialised and
stable after startup.
Ted