\documentclass[a4paper,twocolumn]{article}

\newcommand{\itwoc}{I$^2$C }
\usepackage{graphicx}
\graphicspath{{./images/}}
\title{Student Robotics 2009\\ Peripheral Interconnect}

\begin{document}
\maketitle

All the Student Robotics boards are provided with regulated power for logic circuits and a data connection through the ``RJ11 cables''\footnote{The connectors on the ends of the cables are not necessarily RJ11 connectors.  The naming of these connectors has not been standardised.  It \emph{seems} that the connectors referred to as RJ11 here are most commonly referred to as 4P4C, RJ9, RJ10 or RJ22.}, which are 4-core cables terminated in 4P4C connectors, shown in Figure~\ref{fig:coil}.

The pinout of the 4P4C connector is shown in Table~\ref{tab:4p4c-pinout}.  The socket pin numbering is shown in Figure~\ref{fig:4p4c-pin-num}.

Two sockets connected by an RJ11 cable have the same signal on similarly numbered pins.  For example, pin 1 on the motor board's 4P4C connector connects to pin 1 on a 4P4C connector on the power board.

\begin{figure}
  \begin{center}
    \includegraphics[width=5cm]{./images/coil.jpg}
  \end{center}
  \caption{\label{fig:coil}Cables supplied in SR kit.}
\end{figure}

\begin{table}
  \caption{\label{tab:4p4c-pinout}4P4C Pinout}

  \begin{center}
    \begin{tabular}{|c|c|c|}
      \hline
      \textbf{Pin} & \textbf{Name} & \textbf{Description} \\
      \hline
      1 & VDD & 3.3V logic power rail\\
      2 & SDA & \itwoc data \\
      3 & VSS & Ground \\
      4 & SCL & \itwoc clock\\
      \hline
    \end{tabular}
  \end{center}
\end{table}


\begin{figure}
  \begin{center}
    \includegraphics[width=6.5cm]{./images/4p4c.pdf}
  \end{center}
  \caption{\label{fig:4p4c-pin-num}4P4C Pin Numbering}
\end{figure}



\end{document}