练习在Raspberry Pi上面进行GPIO编程，以及中断控制。
Requirement
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.
