mypapers/drafts/eyebot-compass/eyebot-compass.tex

   1 \documentclass[a4paper,10pt, twocolumn]{article}
   2 \usepackage{graphicx}
   3
   4 \title{Connecting an electronic compass to the Eyebot}
   5
   6 \author{Petter Reinholdtsen $<$pere@td.org.uit.no$>$ \and
   7   Mark Gaynor $<$mark@scouts.org.au$>$ \and
   8   Klaus Schmitt $<$kschmitt@informatik.uni-kl.de$>$}
   9
  10 \date{2000-03-22}
  11
  12 \begin{document}
  13 \maketitle
  14
  15 \section{Introduction}
  16
  17 During the fall of 1999, the CIIPS Glory robot soccer team started to
  18 look into how to connect a compass to the Eyebot controller.
  19 Initially, we used dead reckoning to keep track of the heading.  This
  20 method obviously do not work when the robot is pushed a little of
  21 track, and is also accumulating error when the wheels slip.  To
  22 compensate for these problems and improve our results, we decided to
  23 have a look at electronic compasses.
  24
  25 We first learned about one digital compass, the ``Vector 2X'' from
  26 Precision Navigation, Inc.  The ``Vector 2x'' is circa $3.8 \times 3.3
  27 \times 1$ cm.  This document gives a summary on how this driver works,
  28 and how to connect and set up such compass with the Eyebot.
  29
  30 We later learned about the ``Analog sensor no. 1655'' from Dinsmore
  31 Instrument Company, a analog compass delivering two output indicating
  32 the heading of the compass.  The ``Analog sensor no. 1655'' is circa
  33 1.3 cm in diameter and circa 1.6 cm tall.  This document describe how
  34 to connect and read out the heading from this compass.
  35
  36 \section{Digial compass}
  37
  38 The digital compass is supposed to have accuracy of $2^\circ$.  We
  39 have not tested or verified this at the moment.  We are running the
  40 compass with maximum resolution and in master mode to get the heading
  41 of the compass.  With maximum resolution it gives an updated heading
  42 2.5 times a second.
  43
  44 \subsection{Wiring and connections}
  45
  46 This compass could be used with or without an inverter.  Without
  47 inverters, the compass must be reset in soft software.
  48
  49 With inverters, DOUT 1 and 2 should be inverted, and RESET should be
  50 not connected.
  51
  52 \begin{figure}
  53 \begin{center}
  54 \includegraphics[width=3cm]{vector2x}
  55 \caption{Vector 2x board layout}
  56 \label{fig:vector2x}
  57 \end{center}
  58 \end{figure}
  59
  60 The digital compass get power (VCC) and ground (GND) from the Eyebot
  61 PSD connector.  It needs $5 \pm 0.25$ Volt.  The control signals to
  62 the compass are connected to the Eyebot digital output connector
  63 (DOUT). The control signals from the compass is connected to the servo
  64 connector S12 (TPU 13) and the PSD connector.  The compass connector
  65 names and layout is shown in fig \ref{fig:vector2x}.
  66
  67 The wires should then connect as given in this table, with the
  68 different connectors and connetor pin number given for the Eyebot
  69 side.
  70
  71 To make it possible to mount the compass upside down, the X and Y flip
  72 pins should be connected to ground using a strap, to make it
  73 configurable which way the compass should work.
  74
  75
  76 \begin{center}
  77 \begin{tabular}{|l|l|}
  78 \hline
  79 {\bf Vector2x} & {\bf Eyebot}\\
  80
  81 \hline
  82
  83 P1 (SCLK) & SERVO 1 (TPU) \\
  84
  85 \hline
  86
  87 P16 (GND) & PSD 1 (GND) \\
  88 P15 (VCC) & PSD 3 (VCC) \\
  89 P2  (SDO) & PSD 4 (DIN) \\
  90
  91 \hline
  92
  93 P5  (P/C) & DOUT 1 (DO5) \\
  94 P6  (CAL) & DOUT 2 (DO6) \\
  95 P17 (RESET) & DOUT 3 (DO7) \\
  96
  97 \hline
  98
  99 P10 (Y FLIP) & GND or N/C \\
 100 P11 (X FLIP) & GND or N/C \\
 101
 102 \hline
 103
 104 P3  (SDI) & N/C \\
 105 P4  (SS)  & N/C \\
 106 P7  (RES) & N/C \\
 107 P8  (M/S) & (GND) \\
 108 P9  (BCD) & N/C \\
 109 P12 (CI)  & N/C \\
 110 P13 (EOC) & N/C \\
 111 P14 (RAW) & N/C \\
 112
 113 \hline
 114 \end{tabular}
 115 \end{center}
 116
 117 \subsection{The driver}
 118
 119 The compass driver is included in a modified version of RoBIOS 3.1.
 120 The compass is set up using a hardware description table (HDT) entry
 121 like this:
 122
 123 \begin{verbatim}
 124 compass_type compass =
 125   {0, /* version */
 126   13, /* TPU channel - SCLK */
 127   (void*)OutBase, 5,  /* P/C */
 128   (void*)OutBase, 6,  /* CAL */
 129   (void*)InBase,  5}; /* SDO */
 130
 131 HDT_entry_type HDT[] =
 132 {
 133   ...
 134   {COMPASS,COMPASS,"COMPAS",(void *)&compass},
 135   ...
 136 };
 137
 138 \end{verbatim}
 139
 140 The RoBIOS driver uses one Time Processor Unit (TPU) channel to
 141 generate an interrupt on the rising edge of the SCLK signal.  The
 142 interrupt handler then reads out the current value of the SDO signal
 143 on the digial input line given in the hardware description table.
 144
 145 When the compass is connected without an inverter, the RoBIOS kernel
 146 must be compiled with {\tt USE\_COMPASS\_NO\_INVERTER} defined to use
 147 it properly.
 148
 149 \section{Analog compass}
 150
 151 \begin{figure}
 152 \begin{center}
 153 \includegraphics[width=3cm]{dinsmore-1655}
 154 \caption{Analog compass pins looking down through the sensor}
 155 \label{fig:dinsmore}
 156 \end{center}
 157 \end{figure}
 158
 159 \subsection{Wiring and connections}
 160
 161 - Temperature control when soldering (documentation warning)
 162
 163 \begin{center}
 164 \begin{tabular}{|l|l|}
 165
 166 \hline
 167
 168 VCC & AIN 1 \\
 169
 170 GND & AIN 9 \\
 171
 172 Curve 1 & AIN 3 (CH2) \\
 173
 174 \hline
 175
 176 VCC & AIN 2 \\
 177
 178 GND & AIN 10 \\
 179
 180 Curve 2 & AIN 4 (CH3) \\
 181
 182 \hline
 183 \end{tabular}
 184 \end{center}
 185
 186
 187 \section{Using the compass}
 188
 189 - XXX describe generic API
 190
 191 int COMPASSInit (DeviceSemantics semantics);
 192
 193 int COMPASSCalibrate (int mode);
 194
 195 int COMPASSStart (BOOL cycle);
 196
 197 int COMPASSCheck (void);
 198
 199 int COMPASSGet (void);
 200
 201 int COMPASSStop (void);
 202
 203 int COMPASSRelease (void);
 204
 205
 206 \section*{References}
 207
 208 http://dinsmoregroup.com/dico/
 209
 210 http://www.precisionnav.com/
 211
 212 \end{document}