I hacked a normal keylock and added an RC servo to pull the “tongue” of the lock. A PIC16F1937 is used to control the servo. The keypad has a second PIC 16F1937 which acts as a 10-buttons capacitance touch sensor. The controller PIC stays into sleep all the time to save power. In sleep mode, the device draws 16 micro-amperes. When the operator pulls the door gently, a mechanical switch wakes up the controller PIC (with a pulse to RB0/INT port) which in turn provides power to the touchpad.
To open the door, you pull the handle, enter the code, pull the handle again to activate the servo.
To change code, you pull the handle, enter the code, pull the handle again but you keep it pulled for 3 seconds until you hear the distinctive long beep. Then you enter the new code two times for confirmation.
It can hold codes from 1 to 125 digits for those who have good memory. The keypad has a built-in LDR to check ambient light, and if it is below a certain level, it activates the backlit LEDs (4 SMD blue LEDs).
Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.
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