mypapers/drafts/eyebot-compass/eyebot-compass.html

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   8 <title> Connecting an electronic compass to the Eyebot</title>
   9
  10 <H1 align="center">Connecting an electronic compass to the Eyebot </H1>
  11
  12 <p>
  13
  14 <H3 align=center>Petter Reinholdtsen  &lt; pere@td.org.uit.no &gt; ,
  15   Mark Gaynor  &lt; mark@scouts.org.au &gt; ,
  16   Klaus Schmitt  &lt; kschmitt@informatik.uni-kl.de &gt;  </H3>
  17
  18 <p>
  19
  20 <H3 align=center>2000-03-22 </H3>
  21
  22 <p>
  23          <H2><A NAME="tth_sEc1">
  24 1</A>&nbsp;&nbsp;Introduction</H2>
  25
  26 <p>
  27 During the fall of 1999, the CIIPS Glory robot soccer team started to
  28 look into how to connect a compass to the Eyebot controller.
  29 Initially, we used dead reckoning to keep track of the heading.  This
  30 method obviously do not work when the robot is pushed a little of
  31 track, and is also accumulating error when the wheels slip.  To
  32 compensate for these problems and improve our results, we decided to
  33 have a look at electronic compasses.
  34
  35 <p>
  36 We first learned about one digital compass, the ``Vector 2X'' from
  37 Precision Navigation, Inc.  The ``Vector 2x'' is circa 3.8 &times;3.3&times;1 cm.  This document gives a summary on how this driver works,
  38 and how to connect and set up such compass with the Eyebot.
  39
  40 <p>
  41 We later learned about the ``Analog sensor no. 1655'' from Dinsmore
  42 Instrument Company, a analog compass delivering two output indicating
  43 the heading of the compass.  The ``Analog sensor no. 1655'' is circa
  44 1.3 cm in diameter and circa 1.6 cm tall.  This document describe how
  45 to connect and read out the heading from this compass.
  46
  47 <p>
  48         <H2><A NAME="tth_sEc2">
  49 2</A>&nbsp;&nbsp;Digial compass</H2>
  50
  51 <p>
  52 The digital compass is supposed to have accuracy of 2<sup><font face=symbol>°</font
  53 ></sup>.  We
  54 have not tested or verified this at the moment.  We are running the
  55 compass with maximum resolution and in master mode to get the heading
  56 of the compass.  With maximum resolution it gives an updated heading
  57 2.5 times a second.
  58
  59 <p>
  60       <H3><A NAME="tth_sEc2.1">
  61 2.1</A>&nbsp;&nbsp;Wiring and connections</H3>
  62
  63 <p>
  64 This compass could be used with or without an inverter.  Without
  65 inverters, the compass must be reset in soft software.
  66
  67 <p>
  68 With inverters, DOUT 1 and 2 should be inverted, and RESET should be
  69 not connected.
  70
  71 <p>
  72
  73 <p><A NAME="tth_fIg1">
  74 </A>
  75 <center><img src="vector2x.png" alt="vector2x.png"><br> <center>Figure 1: Vector 2x board layout</center>
  76 <A NAME="fig:vector2x">
  77 </A>
  78 </center>
  79 <p>
  80 <p>
  81 The digital compass get power (VCC) and ground (GND) from the Eyebot
  82 PSD connector.  It needs 5 <font face=symbol>±</font
  83 >0.25 Volt.  The control signals to
  84 the compass are connected to the Eyebot digital output connector
  85 (DOUT). The control signals from the compass is connected to the servo
  86 connector S12 (TPU 13) and the PSD connector.  The compass connector
  87 names and layout is shown in fig <A href="#fig:vector2x">1</A>.
  88
  89 <p>
  90 The wires should then connect as given in this table, with the
  91 different connectors and connetor pin number given for the Eyebot
  92 side.
  93
  94 <p>
  95 To make it possible to mount the compass upside down, the X and Y flip
  96 pins should be connected to ground using a strap, to make it
  97 configurable which way the compass should work.
  98
  99 <p>
 100
 101 <center>
 102 <TaBle border>
 103 <tr><td><b>Vector2x</b> </td><td><b>Eyebot</b></td></tr>
 104 <tr><td>P1 (SCLK) </td><td>SERVO 1 (TPU) </td></tr>
 105 <tr><td>P16 (GND) </td><td>PSD 1 (GND) </td></tr>
 106 <tr><td>P15 (VCC) </td><td>PSD 3 (VCC) </td></tr>
 107 <tr><td>P2  (SDO) </td><td>PSD 4 (DIN) </td></tr>
 108 <tr><td>P5  (P/C) </td><td>DOUT 1 (DO5) </td></tr>
 109 <tr><td>P6  (CAL) </td><td>DOUT 2 (DO6) </td></tr>
 110 <tr><td>P17 (RESET) </td><td>DOUT 3 (DO7) </td></tr>
 111 <tr><td>P10 (Y FLIP) </td><td>GND or N/C </td></tr>
 112 <tr><td>P11 (X FLIP) </td><td>GND or N/C </td></tr>
 113 <tr><td>P3  (SDI) </td><td>N/C </td></tr>
 114 <tr><td>P4  (SS)  </td><td>N/C </td></tr>
 115 <tr><td>P7  (RES) </td><td>N/C </td></tr>
 116 <tr><td>P8  (M/S) </td><td>(GND) </td></tr>
 117 <tr><td>P9  (BCD) </td><td>N/C </td></tr>
 118 <tr><td>P12 (CI)  </td><td>N/C </td></tr>
 119 <tr><td>P13 (EOC) </td><td>N/C </td></tr>
 120 <tr><td>P14 (RAW) </td><td>N/C </td></tr></TaBle>
 121
 122 </center>
 123
 124 <p>
 125       <H3><A NAME="tth_sEc2.2">
 126 2.2</A>&nbsp;&nbsp;The driver</H3>
 127
 128 <p>
 129 The compass driver is included in a modified version of RoBIOS 3.1.
 130 The compass is set up using a hardware description table (HDT) entry
 131 like this:
 132
 133 <p>
 134
 135 <pre>
 136 compass_type compass =
 137   {0, /* version */
 138   13, /* TPU channel - SCLK */
 139   (void*)OutBase, 5,  /* P/C */
 140   (void*)OutBase, 6,  /* CAL */
 141   (void*)InBase,  5}; /* SDO */
 142
 143 HDT_entry_type HDT[] =
 144 {
 145   ...
 146   {COMPASS,COMPASS,"COMPAS",(void *)&amp;compass},
 147   ...
 148 };
 149
 150 </pre>
 151
 152 <p>
 153 The RoBIOS driver uses one Time Processor Unit (TPU) channel to
 154 generate an interrupt on the rising edge of the SCLK signal.  The
 155 interrupt handler then reads out the current value of the SDO signal
 156 on the digial input line given in the hardware description table.
 157
 158 <p>
 159 When the compass is connected without an inverter, the RoBIOS kernel
 160 must be compiled with <tt>USE_COMPASS_NO_INVERTER</tt> defined to use
 161 it properly.
 162
 163 <p>
 164         <H2><A NAME="tth_sEc3">
 165 3</A>&nbsp;&nbsp;Analog compass</H2>
 166
 167 <p>
 168
 169 <p><A NAME="tth_fIg2">
 170 </A>
 171 <center><img src="dinsmore-1655.png" alt="dinsmore-1655.png"><br> <center>Figure 2: Analog compass pins looking down through the sensor</center>
 172 <A NAME="fig:dinsmore">
 173 </A>
 174 </center>
 175 <p>
 176 <p>
 177       <H3><A NAME="tth_sEc3.1">
 178 3.1</A>&nbsp;&nbsp;Wiring and connections</H3>
 179
 180 <p>
 181 - Temperature control when soldering (documentation warning)
 182
 183 <p>
 184
 185 <center>
 186 <TaBle border>
 187 <tr><td>VCC </td><td>AIN 1 </td></tr>
 188 <tr><td>GND </td><td>AIN 9 </td></tr>
 189 <tr><td>Curve 1 </td><td>AIN 3 (CH2) </td></tr>
 190 <tr><td>VCC </td><td>AIN 2 </td></tr>
 191 <tr><td>GND </td><td>AIN 10 </td></tr>
 192 <tr><td>Curve 2 </td><td>AIN 4 (CH3) </td></tr></TaBle>
 193
 194 </center>
 195
 196 <p>
 197         <H2><A NAME="tth_sEc4">
 198 4</A>&nbsp;&nbsp;Using the compass</H2>
 199
 200 <p>
 201 - XXX describe generic API
 202
 203 <p>
 204 int COMPASSInit (DeviceSemantics semantics);
 205
 206 <p>
 207 int COMPASSCalibrate (int mode);
 208
 209 <p>
 210 int COMPASSStart (BOOL cycle);
 211
 212 <p>
 213 int COMPASSCheck (void);
 214
 215 <p>
 216 int COMPASSGet (void);
 217
 218 <p>
 219 int COMPASSStop (void);
 220
 221 <p>
 222 int COMPASSRelease (void);
 223
 224 <p>
 225
 226 <H2>References</H2>
 227
 228 <p>
 229 http://dinsmoregroup.com/dico/
 230
 231 <p>
 232 http://www.precisionnav.com/
 233
 234 <p>
 235
 236 <p><hr><small>File translated from
 237 T<sub><font size="-1">E</font></sub>X
 238 by <a href="http://hutchinson.belmont.ma.us/tth/">
 239 T<sub><font size="-1">T</font></sub>H</a>,
 240 version 2.67.<br>On 26 Apr 2000, 15:24.</small>
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