The code is to interface a DSC PC1500RK alarm keypad. It has 15 keys, 11 LEDs, and a Beeper that can be controlled. This code cycles through all the LEDs in a top-down fashion. The beeper is used ...

12 or 24 hour clock display. Zone input connects detector to keypad to avoid separate wiring back to panel. 5 programmable one-touch function keys with 25 options. LED status indicators. Piezo buzzer ...

But that project only showed you how to interface the Arduino with the keypad — [Doug] went the ... on GitHub in case you also have a DSC 1550 alarm system. It’s a pretty slick hack, so ...