WhyCan Forum(哇酷开发者社区)

	/*
	 * Find AVCC based on the fact that we know the bandgap voltage.
	 * To avoid excessive rounding we multiply 1024 by 1000 before dividing
	 * with the ADC result and then divide the result by 1000 afterwards.
	 * the final result is the supply voltage in millivolts.
	 */
	supply_voltage = ((BG_VOLTAGE * ((1024000) / bandgap)) / 1000);

supply_voltage = BG_VOLTAGE * 1024 / bandgap;