AVR Freaks

	// select channel 1 and AVcc reference
	ADMUX = (1<<REFS0) + 1;
	// 0xD5, precale = /32 = 250Khz, enable and start
	ADCSRA = (1<< ADEN) | (1<<ADSC) | (1<<ADIF) | (5<<ADPS0); 

	// Gonna wait for first conversion to complete but discard (as it's usually inaccuarate)
	do {
	    // keep waiting
	} while((ADCSRA & (1 << ADSC)));		// Wait for A/D conversion to finish

	// Then start the REAL conversion we're interested in....
	ADCSRA |= (1 << ADSC); // start another conversion (discard the first reading)

	do {
	    // keep waiting
	} while((ADCSRA & (1 << ADSC)));		// Wait for A/D conversion to finish

	adc_val = ADC;