Electronic keypads are often used to enter a password to perform a function, such as open a door in a security application. No key is needed, only memorization of a passcode.
Many keypad implementations suffer from several security issues which make a keypad entry system much less secure. Using the same keys on the keypad over and over may lead to someone in the vicinity seeing the pattern of keystrokes used. Also, over time the used keys will start to wear down, allowing a person to more easily guess the digits used on the keypad.
There are methods to thwart the shortcomings noted above. One such was implemented by Stephen B. Hirsch circa 1980. He developed a lock which scrambled where the digits would be located on the keypad. This prevented the use of pattern memorization and created even wear on the keys. There is a demonstration video on YouTube.
The Hirsch Scramblepad required 7-segment displays on the keys, a costly proposition. But that can be simulated on the Adafruit MacroPad.
This project will use the much, much less expensive (and much more fun) Adafruit MacroPad to simulate some of the high security features of locks such as the Hirsch Scramblepad. As the keys do not have displays in them (only colorful LEDs underneath), the scrambled numbers will be displayed on the MacroPad display
The MacroPad will include an indication of success and failure. Optionally, the digital pins on the STEMMA QT port can be used to trigger opening of a solenoid lock with a bit of standard electronics, if desired.
Optional keycaps for the lower left and right of the keypad:
To make the optional solenoid lock driver:
Page last edited March 08, 2024
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