A C project built on a TM4c123GH6PM microcontroller that implements a traffic light of a crossroads with pedestrian buttons using interrupts
#Short Description:
This system is an implementation of a traffic light system. Consisting of 2 road lights for cars (east/west road & north/south road) that contain red, yellow, and green lEDs for each traffic light, and 2 pedestrian lights each containing red, and green lights to signify for pedestrians when they can pass through. The pedestrian traffic lights each have 1 switch to activate them.
#Functionality:
The system manages the road traffic lights by using timers. One timer counts 5 seconds for GREEN light, 2 seconds for YELLOW light, then 1 second where both lights are RED before switching to the other road traffic light and continue the loop.
Whenever a pedestrian presses the pedestrian traffic light button, the normal sequence of the road traffic lights stops to begin the pedestrian traffic light sequence, where the traffic light for the designated button that was pressed is turned to GREEN, its corresponding road traffic light is turned to RED, and the road opposite of the pedestrian traffic light is set to GREEN for 2 seconds. After that duration is done the the pedestrian traffic light returns to its RED state while the road traffic lights resume their behaviour from where they stopped when the button was pressed, then the button for the designated pedestrian traffic light is locked for 1 second to avoid spamming the pedestrian button.
With every light change the system prints out its current state using UART serial communication, explaining which road has which traffic light open currently for both pedestrian traffic lights and car traffic lights.
The system starts with the east/west road light as green and the north/south road light as red and starting the counter at 5 seconds. While also initializing the 2 pedestrian lights as red.
#Basic Scenario:
1- All peripherals initialized and Timer0 starts counting down 5 seconds, GREEN light for east/west road and RED light for north/south road are activated, RED light for both pedestrian lights are turned on.
2- Three Seconds pass and pedestrian at east/west road presses button, GREEN light for east/west pedestrian traffic light turns on, while RED light for east/west car road and GREEN light for north/south car road are turned on, Timer1 starts to countdown 2 seconds.
3- Timer1 ellapses; state of road restored: GREEN light for east/west road and RED light for north/south road are activated, while RED light for east/west pedestrian road is activated. Timer0 is set to count for the remainder 2 seconds. Timer2 starts couting down one second and further requests are locked.
4- Pedestrian presses button at east/west road 0.5 seconds after it is done, the request is cancelled because Timer2 did not ellapse.
5- Timer2 ellapses and pedestrian requests are now unlocked.
6- Timer0 ellapses, YELLOW light for east/west road and RED light for north/south road are activated. Timer0 set to countdown for 2 seconds.
7- Timer0 ellapses, RED light for east/west road and RED light for north/south road are activated. Timer0 set to countdown for 1 second.
8- Timer0 ellapses, RED light for east/west road and GREEN light for north/south road are activated. Timer0 set to countdown for 5 seconds.
#Peripheral Configuration:
Port A: Pin 1 -> UART0 transmitter (output)
Pin 2 -> GREEN light output for east/west road Pin 3 -> YELLOW light output for east/west road Pin 4 -> RED light for output east/west road
Pin 5 -> GREEN light output for north/south road Pin 6 -> YELLOW light output for north/south road Pin 7 -> RED light output for north/south road
Port E: Pin 0 -> GREEN light output for east/west pedestrian light Pin 1 -> RED light output for east/west pedestrian light
Pin 2 -> GREEN light output for north/south pedestrian light Pin 3 -> RED light output for north/south pedestrian light
Port C: Pin 7 -> switch input for north/south pedestrian light
Port F: Pin 4 -> switch input for east/west pedestrian light
=======================================================
Timers: TIMER0 -> 32 bit one-shot countdown timer. Main timer for managing time for car traffic lights. TIMER1 -> 32 bit one-shot countdown timer. Timer that counts 2 seconds for pedestrians to pass TIMER2 -> 32 bit one-shot countdown timer. Timer that counts 1 second after east/west pedestrian light ellapses to limit button presses. TIMER3 -> 32 bit one-shot countdown timer. Timer that counts 1 second after north/south pedestrian light ellapses to limit button presses.