Basic GPIO and Interrupts
Create a program that uses the Raspberry Pi GPIO pins to drive 3 LEDs and respond to 2 pushbutton switches that are located on the supplied breadboard. Use the following GPIO pins for the specified devices:
GPIO pin
Input or Output
Device
17
output
LED 1
27
output
LED 2
22
output
LED 3
23
input
Switch A (pulled high)
24
input
Switch B (pulled low)
The program will have 2 states:
State 1: LEDs are illuminated one after the other in the pattern: 1, 2, 3, 1, 2, 3, etc. Each will be on for about 0.5 second.
State 2: LEDs will be turned on one after the other in the pattern: 3, 2, 1, 3, 2, 1, etc. Each will be lit for about 0.25 second. In other words, the pattern will be twice as fast and in reverse order compared to State 1.
Your program will start in State 1. Configure interrupts so that Switch A triggers a falling-edge interrupt, and Switch B triggers a rising-edge interrupt. When Switch A is pushed, an interrupt service routine (ISR) should put your program into State 2. When Switch B is pushed, the ISR should put your program into State 1.
You may write your program in C or in A64 assembly language, or a combination of both. You can freely use the following files located on D2L as part of your code base: gpio.h, irq.h, link.ld, Makefile, startV2.s, uart.c, and uart.h. You should use “busy loops” to create any delays needed in your program.
Demonstration
You will demo your program to your TA in one of the tutorials shortly after the due date. Your TA will set up a schedule for this in class before the due date.
Bonus (10% if fully implemented)
Use the System Timer peripheral or the Timer (ARM side), plus interrupts to create any delays needed in your program. In other words, replace your “busy loops” with code that uses one of the hardware timers to delay the appropriate amount of time.
New Skills Needed for this Assignment:
Ability to do cross compilation for the Pi
Ability to program GPIO pins for input and output
Ability to configure interrupts
Ability to create an interrupt service routine
Submit the following on D2L:
All files needed to compile your program. This will include the files listed above, plus any custom code that you have created. Your TA will compile and run your program to make sure it is working. If you are doing the bonus part of the assignment, then also include a README file that indicates this.
Computing Machinery II
Assignment 3 Grading
Student:__________________________________________
Configure GPIO output pins 6 ______
Configure GPIO input pins 4 ______
Configure interrupts 4 ______
Interrupt Service Routine(s) 4 ______
Correct behavior for State 1 3 ______
Correct behavior for State 2 3 ______
Correct behavior for pushbuttons 2 ______
Code formatting and documentation 2 ______
Design quality 2 ______
Total 30 ______ _____%
Bonus (10% if fully implemented) _____%
Assignment Grade _____%
