Dorbo is an entry access control program for the Arduino and a host computer. Itopens doors when contactless credendials (key fobs) are presented to readers.Authorized credentials can be configured easily through the serial port while it runs, and they are saved in the Arduino's EEPROM for maximum reliability.

I love box art, so here's a picture:

                     ┌┄┄┄┄┄┄┄┄┄┄┄┄┄┄┐        ┌┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┐
                     ┆ ╔══════════╗ ┆        ┆ ╔═══════════════╗ ┆
╭──────────╮         ┆ ║ Dorbo    ║ ┆        ┆ ║ Dorbo Access  ║ ┆
│ Internet │ ◀─https─▶ ║ Host     ║ ◀─rs-232─▶ ║ Controller    ║ ┆
╰──────────╯         ┆ ║ Software ║ ┆        ┆ ║ Software      ║ ┆
(optional)           ┆ ╚══════════╝ ┆        ┆ ╚═══════════════╝ ┆
                     ┆              ┆        ┆                   ┆
                     ┆ PC-ish       ┆        ┆ Arduino-ish       ┆
                     └┄┄┄┄┄┄┄┄┄┄┄┄┄┄┘        └┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┘

The Dorbo host software runs on a computer that has an RS-232 compatible serial port, can run Python 2.7, and (optionally) can connect to the Internet. This computer can be a PC, laptop, Raspberry Pi, an old SGI Indy, or whatever you have lying around. The Dorbo host software assumes the host computer is running a Unix operating system, but the code is pure Python and could be adapted easily to run on other operating systems.

The host software can be found in the "host" subdirectory in the repo.

The Arduino software runs on an Atmel ATmega328-based microcontroller with an RS-232 serial interface. An Arduino Uno works well, but any similar model with that as many pins and as much SRAM and EEPROM should also work.

Access credentials are stored in the microcontroller's EEPROM so the host computer is not required to be available each time credentials are presented to the system. This makes the system more reliable as the host computer is more complex than the access controller and is more likely to fail. Support for external EEPROM storage could be added to the controller software in order to increase the number of credentials that can be stored on it.

The access controller software can be found in the "arduino" subdirectory in the repo.

The access controller does not have a real-time clock, but it uses an internal timekeeping method that allows it to run for 34.8 years without clock rollover. This period is long enough we can ignore the effects of clock rollover when doing clock math. This simplifies the implementation of several features.

If your access controller will be continuously powered for more than 34.8 years and this period is unacceptably low, the easiest change you can make is to change the type of the "era" field in the time structure to uint16_t. This will give you ~= 8919.6 years before rollover at the expense of slower time arithmetic.