Project 1: Basic Assembly and C Programming

Introduction

In this project, you will program a simple assembly program, and run it on the DE10-Lite board. We will extend the Simple Program from the DE10-Lite setup tutorial. If you have not already done so, we recommend you program this on your board, and verify that toggling the switches toggles the corresponding LED above the switch.

Objectives:

    • Understand how to create projects and program the DE10-Lite board.

    • Use Nios II assembly to do basic bit manipulation of registers.

    • Understand how a CPU interprets and executes instructions.
    • Part 0. Installing Software

We will be using the DE10-Lite board for this course (http://de10-lite.terasic.com/). You will need to purchase one yourself or borrow from another student (though your work should be your own).


Operating System

The software we will use only runs on Windows or Linux (I’m using it on Ubuntu 16.04). You should consider using a virtual machine if you have a Mac—VirtualBox is highly recommended (https://www.virtualbox.org/)—or you can use Parallels, VMWare, or dual boot using Apple Bootcamp.

Utilities

We will be editing code, so you’ll need a text editor. On Linux, you can use vim or emacs. For Windows, NotePad++ (https://notepad-plus-plus.org/) is recommended. We will also need to compress (tarball) files. This utility (tar) will already exist on Linux, but for Windows we recommend 7-zip (http://www.7-zip.org/).

Install the Quartus Software

Download the Quartus Lite 16.1 Software: http://dl.altera.com/16.1/?edition=lite. Note:

this will require you to register/create an Intel account.

This is a 5.8 GB file, so I recommend downloading from campus or somewhere with fast Internet.

Linux

For Linux, extract the tar file ($ tar xf Quartus-lite-16.1.0.196-linux.tar), and run the setup ($ ./setup.sh). Follow the prompts, making note of the directory it installs to (mine installs to ~/intelFPGA_lite/16.1/).

Windows

Run the EXE and install to C:\altera_lite\16.1.

Install the Monitor Program

Download the University Monitor Program for your operating system, for Quartus 16.1: https:// www.intel.com/content/www/us/en/programmable/support/training/university/materials-softw html?&ifup_version=16.1#University-Program-Installer.



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Figure 1: Monitor Program download page — Make sure you’re downloading version 16.1.


Linux

Extract the tar ($ tar xf ./intel_fpga_upds_setup.tar) and run the installer ($ ./install_intel_fpga_upds).

You may need to provide paths to Quartus and to nios2eds. These are in your ~/intelFPGA_lite directory.

For example, I provided:

/home/ewust/intelFPGA_lite/16.1/quartus/

/home/ewust/intelFPGA_lite/16.1/nios2eds/

when prompted by the installer.

As described in usb_blaster.txt, copy the following into a new file in /etc/udev/rules.d/51-usbblaster.rules (as root):

# USB-Blaster

SUBSYSTEM=="usb", ATTRS{idVendor}=="09fb", ATTRS{idProduct}=="6001", MODE="0666"

SUBSYSTEM=="usb", ATTRS{idVendor}=="09fb", ATTRS{idProduct}=="6002", MODE="0666"

SUBSYSTEM=="usb", ATTRS{idVendor}=="09fb", ATTRS{idProduct}=="6003", MODE="0666"

# USB-Blaster II

SUBSYSTEM=="usb", ATTRS{idVendor}=="09fb", ATTRS{idProduct}=="6010", MODE="0666"

SUBSYSTEM=="usb", ATTRS{idVendor}=="09fb", ATTRS{idProduct}=="6810", MODE="0666"

You’ll then need to restart udev (or reboot your computer). Using systemd:

    1. $ sudo service udev restart

    2. $ sudo udevadm control –reload-rules

    3. $ sudo udevadm trigger

You should be able to run the Monitor program:

    • cd ~/intelFPGA_lite/16.1/University_Program/Monitor_Program/

    • ./bin/altera-monitor-program.

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Windows

Run the downloaded EXE, and follow the provided install instructions. If needed, consult Section 2 of the Monitor Program FPGA Nios II Tutorial: ftp://ftp.intel.com/Pub/fpgaup/pub/ Intel_Material/17.0/Tutorials/Intel_FPGA_Monitor_Program_NiosII.pdf.

Running the Program

Once you have installed both Quartus and the Monitor Program, follow the tutorial in Section 3 of the Monitor Program FPGA Nios II Tutorial to learn how to create a new project: ftp://ftp.intel.com/Pub/fpgaup/pub/Intel_Material/17.0/Tutorials/Intel_FPGA_Monitor_ Program_NiosII.pdf.

Follow the tutorial and create a new Simple Program (in Assembly), and verify that it runs on your DE10-Lite, and that you can flip the switches and see the corresponding LEDs change. You will modify the Simple Program for Part 1 of your project next.

If you have trouble with the USB driver (on either Windows or Linux), please consult the Trou-bleshooting guide: https://ecen3350.rocks/static/usb-blaster.pdf






































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Part 1. Basic Adder

The DE10-Lite has 10 switches along the bottom right of the board. In the Simple Program, changing the switches directly changes the LEDs. In this project, we will extend this program to implement an add operation.

We will split the switches in half: the leftmost 5 switches will represent a binary number, while the rightmost 5 switches represent a second binary number. The LEDs will display a binary representation of the sum of these two numbers.

For example, if we wanted to add the numbers 3 and 5, the board should look as follows:




































Figure 2: Adding 3+5 — The leftmost five switches encode the binary number 3 (0b00011) and the rightmost five encode the number 5 (0b00101). The sum of these numbers (8) is displayed in binary on the LEDs: 0b001000.

You should write this program in assembly. You may use the Simple Program as a starting point

    • don’t worry about how the program is reading the state of the switches for now (or writing the LEDs), that code is provided for you in the Simple Program (reproduced below).

You should assume r4 contains the value of the switches (in a single register), and you must modify it accordingly to treat it as two 5-bit numbers that you then add together. Interpret the switches and

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LEDs in big endian, with the most significant bit on the left.

Try different switch configurations to verify that your interpretation of the switches and adding is correct.

You can base your code on the following example (from simple_program.s):

.text


.equ
LEDs,
0xFF200000
.equ
SWITCHES,
0xFF200040
.global _start

_start:


movia
r2, LEDs
# Address of LEDs
movia
r3, SWITCHES
# Address of switches
LOOP:


ldwio
r4, (r3)
# Read the state of switches
# <Your
code to modify r4 here>
stwio
r4, (r2)
# Display the state on LEDs
br
LOOP


.end

Historical fact: The first fully electronic commercially-available calculator was released in 1961. The ANITA (A New Inspiration To Arithmetic) weighed 33 pounds and used vacuum tubes to add, subtract, multiply and divide.

What to submit    A adder.s file that:

    1. Takes two 5-bit binary numbers from the switches and adds them

    2. Displays the resulting binary number on the LEDs


Part 2. Understanding assembly

2.1 Interpreting code

Below is some assembly code. Describe what it does, both in plain English, as well as provide some C code which performs the same functionality. We’re not looking for C code that will compile to this assembly (it won’t, as there is no main function). Instead, provide C code that shows the variables, how they are initialized, and what the code looks like.

The below program is a fully working assembly program—you can load it into the Altera Monitor Program to see how it works. To do that, create a new project of type assembly, and then instead of

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including a getting started example, you’d skip that part and when it gets to add a file, add this file (you have to save it as a .S file and put it into your project’s directory first). You can download this file from https://ecen3350.rocks/static/p1q2.S.

.include "nios_macros.s"

.global _start

_start:

/* the following two instr. (orhi and ori)
are what
movia converts to */
orhi
r2,
r0, %hi(X)
ori
r2,
r2, %lo(X)
movia
r3,
Y

movia
r4,
N

ldw
r4,
0(r4)

add
r5, r0, r0

LABEL:



ldw
r6,
0(r2)

stw
r6,
0(r3)

addi
r2,
r2, 4

addi
r3,
r3, 4

subi
r4,
r4, 1

bgt
r4, r0, LABEL
STOP:



br STOP



.data



N:



.word 6



X:



.word 5, 3,
-6, 19, 8, 12
Y:



.word 0,
0,
0, 0,
0, 0



2.2 Decoding Instructions

Translate the following hex value to Nios II assembly code.

993ff915

2.3 Encoding Instructions

Convert the following assembly into machine code. Your answer should be an 8-digit hex number.

divu r14,r5,r22


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What to submit A plain text file (e.g. not a word document) named writeup.txt containing your answers to part 2. You should format this file using this template:

1.

English/C description of assembly

---

    2. decoded instruction  (e.g. addi r3, r4, 8)

---

    3. encoded instruction  (e.g. 0xDEADBEEF)


Submission Checklist

Upload to Moodle a gzipped tarball (.tar.gz) named project1.identikey.tar.gz. You can make a tarball with $ tar czf project1-identikey.tar.gz ./writeup.txt ./adder.s. The tarball should contain only the following files:

Part 1

An assembly file named adder.s that adds the left/right switches and outputs the result (in binary) to the LEDs.

Part 2

A text file named writeup.txt with your answers to the three short questions, using the template described previously.


























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