MCU operating voltage of 3.3V, LCD, and otherperipheral devices operating voltage of 5V, a single by an
external 9V power supply, through the two-terminal
voltage regulator AS 1117-5.0 and AS1117-3.3,
respectively, to be 5.0V, and 3 3V. AS1117 series regulator
can provide 800mA maximum current, due to the low
power consumption, maximum demand current is less
than 500mA, so with the AS1117 power supply sufficient
to meet the system requirements