Assignment 2 Raspberry Pi environment and ARM assembly programming

Assignment 2
ARM Warmup
Weight: 4% of the total mark
Objective: To get started with the Raspberry Pi environment and ARM assembly programming
Outcome: To implement using the Raspberry Pi’s UART interface an ARM assembly program
that allows drawing object using asterisks, calculate total number of asterisks, and mean of
asterisks grouped by object.
UART: UART stands for Universal Asynchronous Receiver Transmitter. It is a serial communication
protocol between a CPU core (e.g., on the Pi) and a low throughput I/O device, such as a tty terminal.
The Pi supports UART. It also supports a slimmed-down version of UART called miniUART. The Pi
communicates using UART through its GPIO (General Purpose I/O) headers. Initializing and using UART
requires quite a bit of programming. In this assignment, you are only required to use UART as a blackbox.
We are providing with this assignment an object file (.o) that does all the UART work.
Program Steps:
1. Start with displaying the name(s) of creator(s).
2. Your program will first display a numbered list of objects that can be drawn. There will
be three objects: square, rectangle, and triangle.
3. User should select an object to draw, by selecting the object’s number.
a. Check if the input is a number between 1 and 3. If not, display an appropriate
error message.
b. If the user enters -1, then go to step 7.
c. If the user enters q, then go to step 9.
4. Ask for object’s width
a. Check if the input is a number between 3 and 9. If not, then display an
appropriate error message.
5. Draw the selected object.
6. Go to step 3.
7. If the user enters -1, then your program should display a summary as follows:
a. Total number of asterisks used to draw all objects in the current session.
b. Mean of asterisks used to draw all square(s).
c. Mean of asterisks used to draw all triangle(s).
d. Mean of asterisks used to draw all rectangle(s).
8. Got to step 2.
9. Program exits when the user enters q.
Example session:
Notes:
 Width is used to determine the number of asterisks for width
 For a Rectangle object the Height will be Width – 2.
 The algorithm for drawing Triangle(s) can be found here: https://www.codingunit.com/ctutorial-a-star-pyramid-and-string-triangle-using-for-loops.
 For Triangle(s) and Square(s), you only need the Width value to draw them. For a triangle
object, Width is the width of the base.
 When prompting for Width, the user should not be allowed to enter -1 nor q.
UART Notes:
1. Using the UART object file (from D2L), you can call the following subroutines to communicate
over UART:
a. WriteStringUART: This function is used to write a string to the UART line. That is, your
program outputs a string to the tty terminal.
i. arguments:
1. R0: String pointer
2. R1: Length of the string to be written
ii. There is no return value for this function
b. ReadLineUART: This function is used to read from UART the specified number of
characters (Buffer length). Input characters read through UART must be saved in a
buffer created by you.
i. arguments:
1. R0: Address of the buffer.
2. R1: Buffer length (this is the maximum number of characters that can be
read).
ii. Return value in R0: the number of ASCII actual characters read.
2. You will read and write ASCII characters from/to the UART interface. For reading or writing
numbers, you need to convert ASCII characters to numbers after reading, and you need to
convert numbers to ASCII characters before writing. For example, character ‘0’ has an ASCII
value of 48.
3. You can connect to the Pi over UART Line from Linux by opening a new terminal and using the
following command: screen /dev/ttyUSB0 115200
4. If the screen command does not work, you will need to unplug / re-plug the USB to serial link
(the large USB connector plugged into the monitor stand).
Grading:
 Displaying creator names 1
 Input Description 2
 Drawing Objects 5
 Calculating mean 3
 Calculating total 2
 Error messages 2
 Converting ASCII to numbers 4
 Converting numbers to ASCII 4
 Looping back 1
 Efficient code 2
 Termination 1
 Displaying summary 2
 Well documented code 1
Total 30 points
Programs that do not compile cannot receive more than 5 points. Programs that compile, but do not
implement any of the functionality described above can receive a maximum of 7 points.
Teams: You are advised to work with another student in class in order to complete the assignment, but
you are not required to do so. You and your partner must be in tutorials taught by the same TA. Peer
evaluation in teams may be conducted.
Submission: Submit your source code to the drop box on D2L. Only one submission per team is required.
Late Submission Policy: Late submissions will be penalized as follows:
-12.5% for each late day or portion of a day for the first two days
-25% for each additional day or portion of a day after the first two days
Hence, no submissions will be accepted after 5 days (including weekend days) of the announced
deadline
.
D2L Marks: Any marks posted on D2L or made available using any other mean are tentative and are
subject to change (after posting). They can go UP or DOWN due to necessary corrections.