[~andy/csm213a-hw] / hw1 / report.htm

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1. Prepare a simple web page (I recommend using sites.google.com or just a plan
   google doc and publishing it) with the following:

   a. Text that briefly describes your software organization for mbed and the
      host (e.g. event handlers, threads etc. and what they do in plain text),
      and the precise protocol and format for data that is exchanged between
      the host and the mbed.

   b. URLS for: (i) Code for PC as a .zip file (you could put the .zip file on
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2. When you have everything ready, fill the form at
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<h2>Brief Description</h2>

<p>The objective of this homework is to explore organizing embedded software
   using mbed as the platform in context of a simple system. Sensor data flows
   in the direction of: mbed → PC → Xively.</p>

<h2>Embedded Target Design</h2>

<p>The mbed code is organized in a single main.cpp file which invokes libraries
   to read the sensor data. The Accelerometer, Magnetometer, and Touch Sensor
   libraries were acquired through the mbed website and the Analog Input and
   Output libraries were included in the mbed SDK.</p>

<p>The software consists of preemptable sensor loop running at a fixed rate, a
   serial data receive interrupt handler, and a direct-memory access serial
   transmitter. On each iteration of the sensor loop a time counter is checked
   to determine which sensor are due for reading. Each sensor function polls
   data from the sensor, packs the data into an output frame, and then write
   the frame to the output queue.</p>

<p><i>Note: the sensor reading was originally performed in a timer interrupt
      routine, however, it moved to a background task to minimize interference
      with the reception of serial commands.</i></p>

<h2>Data Logger Design</h2>

The data logger is implemented as a Graphical User Interface using Python and
the GTK+ Toolkit. The source code is organized around the following classes:

<ul>
        <li>A Main class which performs basic initialization</li>
        <li>A Config class for storing user preferences</li>
        <li>A Device class to interfaces with the mbed using PySerial</li>
        <li>A Logger class to transmit the recorded data to Xively</li>
        <li>A Visual class to display the user interface</li>
</ul>

<h2>Data Collection</h2>

<p>The mbed FRDM-KL46Z is responsible for data collection and sending it to the
   host via Serial-over-USB. Sensors data is collected at a periodic rate and
   is transmitted to the PC using the DATA_FRAME format shown below. The Serial
   data transmit is handled by the KL46Z Direct-Memory Access (DMA) controller
   so that data transmission does not block the CPU. When sensor data is ready,
   it is packed and appended to a transmit buffer. At the end of the periodic
   loop the DMA controller is enabled and data transmission begins</p>

<p>Commands are sent to the mbed using the COMMAND_FRAME format and are
   processed using a serial interrupt handler. The handler parses the incoming
   messages and performs command processing when a valid COMMAND_FRAME is
   received.</p>

<h2>Serial Message Formats</h2>

<p>As is mentioned above, the mbed and communicate via UART, thus working based
   on serial protocol. Since the mbed can be perceived as a slave to the PC, we
   let the mbed collect and send DATA_FRAME, while PC is responsible for
   generating COMMAND_FRAME. The frame structure is as follows:</p>

<h3>Data Frame</h3>
<table cellspacing="0" cellpadding="2" border="1">
<tr><td>1 Byte</td><td>4 bits  </td><td>4 bits </td><td>1 Byte </td><td>(Varied Size)</td><td>1 Byte</td></tr>
<tr><td>HEADER</td><td>dataType</td><td>snsType</td><td>dataNum</td><td>data         </td><td>TAIL  </td></tr>
</table>

<h4>Field Descriptions</h4>
<table cellspacing="0" cellpadding="2" border="1">
        <tr><t4>HEADER:  </td><td>0x02, constant, indicating the start of a frame</td></tr>
        <tr><td>dataType:</td><td>Data Type:<table>
                <tr><td style="padding-left:3em">0-  int8</td><td style="padding-left:1em">1 -  int16</td><td style="padding-left:1em">2 -  int32</td></tr>
                <tr><td style="padding-left:3em">3- uint8</td><td style="padding-left:1em">4 - uint16</td><td style="padding-left:1em">5 - uint32</td></tr>
                <tr><td style="padding-left:3em">6- float</td><td style="padding-left:1em">7 - double</td><td style="padding-left:1em">          </td></tr>
        </table></td></tr>
        <tr><td>snsType: </td><td>Sensor Type:<ul style="list-style-type: none;">
                <li>0 - LIGHT_SENSOR</li>
                <li>1 - ACC_SENSOR</li>
                <li>2 - MAG_SENSOR</li>
                <li>3 - TOUCH_SENSOR</li>
                <li>4 - ADC_SENSOR</li>
        </ul></td></tr>
        <tr><td>dataNum: </td><td>Data number. Number of data pack in the frame</td></tr>
        <tr><td>data:    </td><td>Sensor data. How it is packed is based on dataType and dataNum</td></tr>
        <tr><td>TAIL:    </td><td>0x0A, constant, indicating the end of a frame</td></tr>
</table>

<h3>Command Frame</h3>
<table cellspacing="0" cellpadding="2" border="1">
<tr><td>1 Byte</td><td>4 bits </td><td>4 bits </td><td>4 Byte  </td><td>1 Byte</td></tr>
<tr><td>HEADER</td><td>cmdType</td><td>snsType</td><td>Interval</td><td>TAIL  </td></tr>
</table>

<h4>Field Descriptions</h4>
<table cellspacing="0" cellpadding="2" border="1">
        <tr><td>HEADER:  </td><td>0x02, constant, indicating the start of a frame</td></tr>
        <tr><td>cmdType: </td><td>Command Type:<ul style="list-style-type: none;">
                <li>0 - START</li>
                <li>1 - STOP</li>
                <li>2 - SET_INT</li>
        </td></tr>
        <tr><td>Interval:</td><td>sampling rate. Representing a float of 4 Bytes.</td></tr>
        <tr><td>TAIL:    </td><td>0x0A, constant, indicating the end of a frame</td></tr>
</table>

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   a. Text that briefly describes your software organization for mbed and the
      host (e.g. event handlers, threads etc. and what they do in plain text),
      and the precise protocol and format for data that is exchanged between
      the host and the mbed.
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<h2>Sampling Rate</h2>

<p>The following sampling rates were obtained for each sensor, and a combined
   sampling rate when all sensors are sampling simultaneously. Data collection
   was performed using a 230400 serial baud rate.</p>

<table>
        <tr><th>Sensor           </th><th style="padding-left: 1em;">Sampling Rate</th></tr>
        <tr><td>Accelerometer    </td><td style="padding-left: 1em;"> 560 Hz      </td></tr>
        <tr><td>Magnetometer     </td><td style="padding-left: 1em;"> 530 Hz      </td></tr>
        <tr><td>Touch Sensor     </td><td style="padding-left: 1em;">1930 Hz      </td></tr>
        <tr><td>Light Sensor     </td><td style="padding-left: 1em;">2414 Hz      </td></tr>
        <tr><td>Analog to Digital</td><td style="padding-left: 1em;"> 820 Hz      </td></tr>
        <tr><td>All Combined     </td><td style="padding-left: 1em;"> 150 Hz      </td></tr>
</table>

<h2>Online Submission</h2>

<dl>
        <dt>Code for mbed</dt>
        <dd><a href="http://mbed.org/users/andy753421/code/Sensors/">http://mbed.org/users/andy753421/code/Sensors/</a></dd>

        <dt>Code for PC</dt>
        <dd><a href="https://sites.google.com/a/g.ucla.edu/ibeaconnav/homework1/python.zip">https://sites.google.com/a/g.ucla.edu/ibeaconnav/homework1/python.zip</a></dd>


        <dt>Video Link</dt>
        <dd>(we will do a demo during office hours)</dd>
</dl>