Assignment #2 Solution

AVR Studio Project




As in assignment 1, you should create a new assembly language project in AVR Studio for this assignment. Download the sample code and add the files to the project.




Please note that this assignment comes in two parts. Part 1 is a problem set on conneX. You fill your answers directly on conneX. Part 2 is a set of programming assignments that are given below.




Assignment 2 Part 1: Problem set on conneX




Complete the Assignment 2 Part1 problem set on conneX. This is available in Tests & Quizzes section.




Assignment 2 Part II – Assembly Programming Assignments




Question 1: Lighting the LEDs




As you've seen in the lab, the boards include a 6 LED strip, where each LED can be controlled independently from the others. Although the LEDs are wired to adjacent Arduino pins, they are controlled using two AVR ports: PORTB and PORTL. The exact mapping is shown in the table below:




Pin
PORT
Bit #






42
L
7






44
L
5






46
L
3






48
L
1






50
B
3






52
B
1









You should modify the code in a2q1.asm so that it displays the binary value in R0 of bits 5-0 in binary using the 6 LEDs ignoring bits 6 and 7. You should consider the LED on Pin 42 to be the least-significant bit and the LED on Pin 52 to be the most-significant bit.




For example, if R0 contains the value 0x13, the LEDs should look like:




Pin
52
50
48
46
44
42














Value
OFF
ON
OFF
OFF
ON
ON

















Be sure to test your code on several different values. Your instructor's solution used a combination of ANDI and BRNE instructions to test the individual bits in R0 and then used ORI to set individual bits in two output registers: one that is output to PORTL and another that is output to PORTB.







Question 2 – Subroutines and timing




Using the code you wrote in Question 1 above and the delay code provided to you in Lab 4, using a2q2.asm write a program that does the following:

counter = 0

start:

display counter in binary on the LEDs

counter = counter + 1

delay between 100 and 200 milliseconds

goto start




First you should turn the code you wrote in Question 1 above into a subroutine called display. Then write a main program that implements the algorithm shown above. It will be easiest if you use R0 for your counter.




Question 3 – Button press counting




Using the button code and delay code provided to you in Lab 4, using a2q3.asm that is provided to you write a program that does the following:




counter = 0

start:

if button pressed

counter = counter + 1

delay between 100 and 200 milliseconds

display counter in binary on the LEDs

goto start













Question 4 – Improved button code




Improve the button code so that it correctly determines which button has been pressed. Study the comments in a2q4.asm for details on the values returned from the analog to digital conversion when the buttons are pressed.




You've been provided with a main program – you'll need to fix the button subroutine and include your

LED display subroutine. Once you do that, a different light should come on for each button you press.

Your instructor's solution used the BRSH instruction.




Submission




Submit your a2q1.asm, a2q2.asm, a2q3.asm and a2q4.asm using connex. Do NOT submit your project file – just the .asm files.







Grading

If you submit a program that does not assemble you will receive 0 for that part of the assignment.




Question 1
5 marks




Question 2
5 marks




Question 3
6 marks




Question 4
4 marks




Total
20 marks