+----+
| | +-----------+
| | | RFID |
| | +--+ Reader |
| | | +-----------+
+--------------+ | | +---------------+ |
| | | | | | | +-----------+
| RaspberryPi +----(UART)----+ Arduino +--+--+ Keypad |
| | | | | (frontend) | | +-----------+
+------+-------+ | | +---------------+ |
| | | | +-----------+
| | | +--+ Display |
+-----+------+ | | +-----------+
| Door lock | | |
+------------+ | |
+----+