CSE 230 Project 4: Pardon the Interruption

Learning Objectives:

_Implement an interrupt service routine in a program containing existing functionality

The Task

In this project, you will be adding an interrupt service routine (ISR) to an existing program. The program is already fully functional hexadecimal counter that shows the current counter value on the seven-segment display. You will use the timer to generate an interrupt every x cycles (where x can be between 100 and 200 cycles). Your ISR needs to do the following things:

1. Toggle all eight LEDs (i.e. if they are all off, they should all be turned on and if they are already on, turn them off)

2. Perform any tasks necessary to allow another timer interrupt within 100 to 200 cycles

No changes should be made to the existing main loop or sseg_display.asm. Code should only be added following the TODO comments.

Skeleton File to work with below:

.org 0x10000000

li $sp, 0x10fffffc # Stack pointer initialization

li $s0, sseg_lut# Lookup table address used by sseg_display

lui $s1, 0xf070# Interrupt controller register

lui $s2, 0xf0a0# Seven segment display

# ****************************

# TODO: enable interrupts below

# ****************************

# NOTE: Do not add or modify any code within this main loop

main:

jal sseg_display

nop

addiu $a0, $a0, 1

j main

nop

# ****************************************

# TODO: add interrupt service routine below

# ****************************************