LSSmartLight: RFID Lighting Controller

A programmable lighting controller for a meeting room, built for the Digital Systems and Microprocessors course (La Salle, 2024–25). A user taps an RFID card on entry, and six lights fade to that user's saved brightness levels. Tapping again turns everything off. Each user can change their preferences from a keypad, and a serial menu on a PC shows the system state.

Demo

A card is tapped on the reader, the lights fade to that user's saved levels, and the LCD and the serial menu on the PC update to match.

Features

• RFID check-in and check-out: an MFRC522 (RC522) module is driven over bit-banged SPI, since the PIC's hardware SPI was not allowed.
  • If the room is empty, a card loads that user's light profile.
  • If the same card is tapped again, the user leaves and all lights turn off.
  • If a different card is tapped, it takes over the room and loads its own profile.
  • Up to 8 users are stored. Unknown cards are reported over serial and otherwise ignored.
• Six dimmable lights: each LED is driven by software PWM at 50 Hz with 11 intensity levels (0–9, plus A for full).
• 3×4 keypad:
  • Press <light><level> to set a light, for example 3 then 7 puts light 3 at 70%. Use * for full brightness.
  • Changes are saved to the current user's profile.
  • A short press of # opens the serial menu. Holding # for 3 s clears every user's settings.
• 16×2 LCD: shows the current user, a clock and all six light levels, for example F 16:30 1-0 2-3 3-3 4-0 5-9 6-A.
• Serial menu (UART at 115200 baud, opened with Esc):
  1. Who is in the room?
  2. Show settings for all registered users
  3. Set the system time

Architecture

The firmware is written in C and uses a cooperative multitasking design. Each module is an abstract data type (TAD) with a non-blocking state machine, its "motor". main() calls every motor in turn inside an endless loop. A single TMR0 interrupt every 2 ms drives a set of virtual software timers that all modules share.

Module	Responsibility
main.c	Init and the cooperative main loop
TAD_TIMER	TMR0 interrupt and virtual timers
TRFID	MFRC522 driver over software SPI, the UID whitelist and per-user light profiles
TAD_KEYPAD	Keypad scanning, debouncing, and short/long press detection
TAD_LED1–TAD_LED6	One software-PWM generator for each light
TAD_Menu	Serial menu and command handling
TAD_SIO	UART driver
TAD_Time	Real-time clock (HH:MM)
LcTLCD	Non-blocking HD44780 LCD driver

Hardware

• PIC18F4321 with a 10 MHz crystal and HSPLL, giving a 40 MHz clock
• RFID-RC522 module: RC0 is MISO, RC1 MOSI, RC2 SCK, RC3 CS and RC4 RST
• Six lights on RA0–RA5
• 3×4 matrix keypad and a 16×2 character LCD
• USB-TTL serial link to a PC on RC6/RC7

Building

1. Open firmware/Setup_P2.X in MPLAB X with the XC8 compiler installed.
2. Build and program a PIC18F4321 with a PICkit.

You can also flash the prebuilt firmware/lssmartlight.hex directly.

The accepted card UIDs and their default light levels are hard-coded in TRFID.c (acceptedUIDs / userLEDs). Replace them with your own cards' UIDs.

Photos

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Authors

Teodor Arsovski and Mateja Džunić