Power-Saving Keypad Controls Multiple Keys Through One Mcu Pin

Abstract

Power-saving Keypad controls multiple keys using bidirectional I/O pin on the microcontroller with resistors and a capacitor. The keypad can save power by charging the capacitor only once for each key press. The microcontroller enters sleep mode and remains asleep until the key is released and the state of I/O changes back to high. It also has the capability to determine the charging time with regulated voltage. The microcontroller starts functioning when a change in I/O's state generates an interrupt. The capacitors also starts charging to the High-state voltage with the changing I/O.