lab5-writeup.tex

% template created by: Russell Haering. arr. Joseph Crop
\documentclass[12pt,letterpaper]{article}
\usepackage{anysize}
\marginsize{2cm}{2cm}{1cm}{1cm}

\begin{document}

\begin{titlepage}
    \vspace*{4cm}
    \begin{flushright}
    {\huge
        ECE 375 Lab 5\\[1cm]
    }
    {\large
        IR Remote Control Robot
    }
    \end{flushright}
    \begin{flushleft}
    Lab Time: Tuesday 5-7
    \end{flushleft}
    \begin{flushright}
    Emily Dunham 
    \vfill
    \rule{5in}{.5mm}\\
    TA Signature
    \end{flushright}

\end{titlepage}

\section{Introduction}

This lab requires us to create a remote controlled tekbot capable of playing
freeze tag. Since I had access to two lab boards (a friend took this class
last year) and didn't want to work with a partner or a robot on wheels, I
modified the task slightly so that the slave/"robot" board will light up a
labeled LED instead of performing a drive action, and its buttons will provide
the whisker interrupts. 

In the remote controller, I added the feature that it should light up a
labeled LED each time it recieves a button press, so that the person
controlling the robot gets visual confirmation that their instruction was
sent. I also added a "cheat freeze" feature to the remote for testing
purposes, so that I can test what the robot does when it recieves the freeze
signal. 

\section{Internal Register Definitions and Constants}
\subsection{Robot:}
\begin{verbatim}
; assorted variables, counters, and scribble registers
.def    mpr         = r16       ; Multi-Purpose Register
.def    timesFrozen = r17       ; stop permanently after 3
.def    waitctr     = r18
.def    input       = r19
.def    temp        = r20
.def    action      = r21
.def    status      = r22
.def    innerloop   = r23
.def    outerloop   = r24
.equ    WTIM        = 100       ; time in wait loop
; the commands specified in the lab handout
.equ    MovFwd          = 0b10110000 ;Move Forwards Command
.equ    MovBck          = 0b10000000 ;Move Backwards Command
.equ    TurnR           = 0b10100000 ;Turn Right Command
.equ    TurnL           = 0b10010000 ;Turn Left Command
.equ    Halt            = 0b11001000 ;Halt Command
.equ    SendFreeze      = 0b11111000
.equ    Frozen          = 0b01010101
; constants for output (simulated move actions)
.equ    fwdlights       = 0b10000000
.equ    backlights      = 0b01000000
.equ    rightlights     = 0b00100000
.equ    leftlights      = 0b00010000
.equ    stoplights      = 0b00001000
.equ    freezesendlights= 0b00000100
.equ    frozenlights    = 0b00000001
; identity
.equ    BotID           = 0b01000000 ; must match remote
\end{verbatim}
\subsection{Remote:}
\begin{verbatim}
;added the led register to store what the lights should be displaying
.def    mpr     = r16            ; Multi-Purpose Register
.def    led     = r17            ; Light combo 
.def    cmd     = r18            ; which command to send
.def    temp    = r19            ; and some scribble room.
; Use these commands between the remote and TekBot
; just write them out so they won't change if somebody pokes
; a seemingly arbitrary value elsewhere in the code
.equ    MovFwd      = 0b10110000 ;Move Forwards Command
.equ    MovBck      = 0b10000000 ;Move Backwards Command
.equ    TurnR       = 0b10100000 ;Turn Right Command
.equ    TurnL       = 0b10010000 ;Turn Left Command
.equ    Halt        = 0b11001000 ;Halt Command
.equ    SendFrz     = 0b11111000
; 
.equ    BotID       = 0b01000000 ; chose this arbitrarily since IDs weren't
assigned

\end{verbatim}

\section{Interrupt Vectors}
\section{Robot:}
\begin{verbatim}
\end{verbatim}

\section{Remote:}
\begin{verbatim}
\end{verbatim}


\section{Program Initialization}
\section{Robot:}
\begin{verbatim}
\end{verbatim}

\section{Remote:}
\begin{verbatim}
\end{verbatim}



\section{Main Program and Subroutines:}

See attached printouts, since the code is rather long.

\section{Additional Questions}

None given in handout.
    
\section{Difficulties}

Although I found the task difficult to understand at first, I tracked down a
partially-complete and well-commented version of a lab similar to this posted
by a former student on GitHub. I read that code's comments in order to
understand the correct structure of the program's logic in assembly, and then
was able to design my own solution to the problem in a way that avoided
several issues that I discovered while reading the alternate solution. 

The ATMEGA128 datasheet was also extremely helpful, and provided examples of
large portions of the code almost completely ready to go. 

\section{Conclusion}

This is yet another reminder of why we invented higher-level languages: a
simple robot like this requires hundreds of lines of assembly code, which
makes it nearly impossible to fit any reasonable amount of useful information
on the screen at a given time. 

\section{Source Code}
Source code is printed separately and attached this week.
\end{document}