+<?xml version="1.0" encoding="utf-8" ?>
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+"/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd">
+
+<article>
+ <articleinfo>
+ <title>AltOS Telemetry</title>
+ <subtitle>Packet Definitions</subtitle>
+ <author>
+ <firstname>Keith</firstname>
+ <surname>Packard</surname>
+ </author>
+ <copyright>
+ <year>2011</year>
+ <holder>Keith Packard</holder>
+ </copyright>
+ <legalnotice>
+ <para>
+ This document is released under the terms of the
+ <ulink url="http://creativecommons.org/licenses/by-sa/3.0/">
+ Creative Commons ShareAlike 3.0
+ </ulink>
+ license.
+ </para>
+ </legalnotice>
+ <revhistory>
+ <revision>
+ <revnumber>0.1</revnumber>
+ <date>01 July 2011</date>
+ <revremark>Initial content</revremark>
+ </revision>
+ </revhistory>
+ </articleinfo>
+ <section>
+ <title>History and Motivation</title>
+ <para>
+ The original AltoOS telemetry mechanism encoded everything
+ available piece of information on the TeleMetrum hardware into a
+ single unified packet. Initially, the packets contained very
+ little data—some raw sensor readings along with the current GPS
+ coordinates when a GPS receiver was connected. Over time, the
+ amount of data grew to include sensor calibration data, GPS
+ satellite information and a host of internal state information
+ designed to help diagnose flight failures in case of a loss of
+ the on-board flight data.
+ </para>
+ <para>
+ Because every packet contained all of the data, packets were
+ huge—95 bytes long. Much of the information was also specific to
+ the TeleMetrum hardware. With the introduction of the TeleMini
+ flight computer, most of the data contained in the telemetry
+ packets was unavailable. Initially, a shorter, but still
+ comprehensive packet was implemented. This required that the
+ ground station be pre-configured as to which kind of packet to
+ expect.
+ </para>
+ <para>
+ The development of several companion boards also made the
+ shortcomings evident—each companion board would want to include
+ telemetry data in the radio link; with the original design, the
+ packet would have to hold the new data as well, requiring
+ additional TeleMetrum and ground station changes.
+ </para>
+ </section>
+ <section>
+ <title>Packet Format Design</title>
+ <para>
+ AltOS telemetry data is split into multiple different packets,
+ all the same size, but each includs an identifier so that the
+ ground station can distinguish among different types. A single
+ flight board will transmit multiple packet types, each type on a
+ different schedule. The ground software need look for only a
+ single packet size, and then decode the information within the
+ packet and merge data from multiple packets to construct the
+ full flight computer state.
+ </para>
+ <para>
+ Each AltOS packet is 32 bytes long. This size was chosen based
+ on the known telemetry data requirements. The power of two size
+ allows them to be stored easily in flash memory without having
+ them split across blocks or leaving gaps at the end.
+ </para>
+ <para>
+ All packet types start with a five byte header which encodes the
+ device serial number, device clock value and the packet
+ type. The remaining 27 bytes encode type-specific data.
+ </para>
+ </section>
+ <section>
+ <title>Packet Formats</title>
+ This section first defines the packet header common to all packets
+ and then the per-packet data layout.
+ <section>
+ <title>Packet Header</title>
+ <table frame='all'>
+ <title>Telemetry Packet Header</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0</entry>
+ <entry>uint16_t</entry>
+ <entry>serial</entry>
+ <entry>Device serial Number</entry>
+ </row>
+ <row>
+ <entry>2</entry>
+ <entry>uint16_t</entry>
+ <entry>tick</entry>
+ <entry>Device time in 100ths of a second</entry>
+ </row>
+ <row>
+ <entry>4</entry>
+ <entry>uint8_t</entry>
+ <entry>type</entry>
+ <entry>Packet type</entry>
+ </row>
+ <row>
+ <entry>5</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ <para>
+ Each packet starts with these five bytes which serve to identify
+ which device has transmitted the packet, when it was transmitted
+ and what the rest of the packet contains.
+ </para>
+ </section>
+ <section>
+ <title>Sensor Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x01</entry>
+ <entry>TeleMetrum Sensor Data</entry>
+ </row>
+ <row>
+ <entry>0x02</entry>
+ <entry>TeleMini Sensor Data</entry>
+ </row>
+ <row>
+ <entry>0x03</entry>
+ <entry>TeleNano Sensor Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <para>
+ TeleMetrum, TeleMini and TeleNano share this same packet
+ format for sensor data. Each uses a distinct packet type so
+ that the receiver knows which data values are valid and which
+ are undefined.
+ </para>
+ <table frame='all'>
+ <title>Sensor Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>state</entry><entry>Flight state</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>int16_t</entry><entry>accel</entry><entry>accelerometer (TM only)</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int16_t</entry><entry>pres</entry><entry>pressure sensor</entry>
+ </row>
+ <row>
+ <entry>10</entry><entry>int16_t</entry><entry>temp</entry><entry>temperature sensor</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>int16_t</entry><entry>v_batt</entry><entry>battery voltage</entry>
+ </row>
+ <row>
+ <entry>14</entry><entry>int16_t</entry><entry>sense_d</entry><entry>drogue continuity sense (TM/Tm)</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>int16_t</entry><entry>sense_m</entry><entry>main continuity sense (TM/Tm)</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>int16_t</entry><entry>accel</entry><entry>m/s² * 16</entry>
+ </row>
+ <row>
+ <entry>20</entry><entry>int16_t</entry><entry>speed</entry><entry>m/s * 16</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>int16_t</entry><entry>height</entry><entry>m</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>int16_t</entry><entry>ground_accel</entry><entry>TM</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>int16_t</entry><entry>ground_pres</entry><entry>Average barometer reading on ground</entry>
+ </row>
+ <row>
+ <entry>28</entry><entry>int16_t</entry><entry>accel_plus_g</entry><entry>TM</entry>
+ </row>
+ <row>
+ <entry>30</entry><entry>int16_t</entry><entry>accel_minus_g</entry><entry>TM</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
+ <section>
+ <title>Configuration Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x04</entry>
+ <entry>Configuration Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <table frame='all'>
+ <title>Sensor Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>type</entry><entry>Device type</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>uint16_t</entry><entry>flight</entry><entry>Flight number</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>uint8_t</entry><entry>config_major</entry><entry>Config major version</entry>
+ </row>
+ <row>
+ <entry>9</entry><entry>uint8_t</entry><entry>config_minor</entry><entry>Config minor version</entry>
+ </row>
+ <row>
+ <entry>10</entry><entry>uint16_t</entry><entry>main_deploy</entry><entry>Main deploy alt in meters</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>uint32_t</entry><entry>flight_log_max</entry><entry>Maximum flight log size (B)</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>char</entry><entry>callsign[8]</entry><entry>Radio operator identifier</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>char</entry><entry>version[8]</entry><entry>Software version identifier</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
+ <section>
+ <title>GPS Location</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x05</entry>
+ <entry>GPS Location</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <table frame='all'>
+ <title>GPS Location Packet Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>flags</entry><entry>GPS Flags (see below)</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>int16_t</entry><entry>altitude</entry><entry>m</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>int32_t</entry><entry>latitude</entry><entry>degrees * 10<superscript>7</superscript></entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>int32_t</entry><entry>longitude</entry><entry>degrees * 10<superscript>7</superscript></entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>uint8_t</entry><entry>year</entry>
+ </row>
+ <row>
+ <entry>17</entry><entry>uint8_t</entry><entry>month</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>uint8_t</entry><entry>day</entry>
+ </row>
+ <row>
+ <entry>19</entry><entry>uint8_t</entry><entry>hour</entry>
+ </row>
+ <row>
+ <entry>20</entry><entry>uint8_t</entry><entry>minute</entry>
+ </row>
+ <row>
+ <entry>21</entry><entry>uint8_t</entry><entry>second</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>uint8_t</entry><entry>pdop</entry><entry>* 5</entry>
+ </row>
+ <row>
+ <entry>23</entry><entry>uint8_t</entry><entry>hdop</entry><entry>* 5</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>uint8_t</entry><entry>vdop</entry><entry>* 5</entry>
+ </row>
+ <row>
+ <entry>25</entry><entry>uint8_t</entry><entry>mode</entry><entry>N, A, D, E, M, S</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>uint16_t</entry><entry>ground_speed</entry><entry>cm/s</entry>
+ </row>
+ <row>
+ <entry>28</entry><entry>uint8_t</entry><entry>course</entry><entry>/ 2</entry>
+ </row>
+ <row>
+ <entry>29</entry><entry>uint8_t</entry><entry>unused[2]</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
+ <section>
+ <title>GPS Satellite Data</title>
+ <informaltable frame='none' label='' tocentry='0'>
+ <tgroup cols='2' align='center' colsep='1' rowsep='1'>
+ <colspec align='center' colwidth='*' colname='Offset'/>
+ <colspec align='left' colwidth='3*' colname='Description'/>
+ <thead>
+ <row>
+ <entry>Type</entry>
+ <entry>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>0x06</entry>
+ <entry>GPS Satellite Data</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </informaltable>
+ <table frame='all'>
+ <title>GPS Satellite Data Contents</title>
+ <tgroup cols='4' align='center' colsep='1' rowsep='1'>
+ <colspec align='right' colwidth='*' colname='Offset'/>
+ <colspec align='center' colwidth='3*' colname='Data Type'/>
+ <colspec align='left' colwidth='3*' colname='Name'/>
+ <colspec align='left' colwidth='9*' colname='Description'/>
+ <thead>
+ <row>
+ <entry align='center'>Offset</entry>
+ <entry align='center'>Data Type</entry>
+ <entry align='center'>Name</entry>
+ <entry align='center'>Description</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry>5</entry><entry>uint8_t</entry><entry>channels</entry>
+ </row>
+ <row>
+ <entry>6</entry><entry>uint8_t</entry><entry>sat_0_id</entry>
+ </row>
+ <row>
+ <entry>7</entry><entry>uint8_t</entry><entry>sat_0_c_n_1</entry>
+ </row>
+ <row>
+ <entry>8</entry><entry>uint8_t</entry><entry>sat_1_id</entry>
+ </row>
+ <row>
+ <entry>9</entry><entry>uint8_t</entry><entry>sat_1_c_n_1</entry>
+ </row>
+ <row>
+ <entry>10</entry><entry>uint8_t</entry><entry>sat_2_id</entry>
+ </row>
+ <row>
+ <entry>11</entry><entry>uint8_t</entry><entry>sat_2_c_n_1</entry>
+ </row>
+ <row>
+ <entry>12</entry><entry>uint8_t</entry><entry>sat_3_id</entry>
+ </row>
+ <row>
+ <entry>13</entry><entry>uint8_t</entry><entry>sat_3_c_n_1</entry>
+ </row>
+ <row>
+ <entry>14</entry><entry>uint8_t</entry><entry>sat_4_id</entry>
+ </row>
+ <row>
+ <entry>15</entry><entry>uint8_t</entry><entry>sat_4_c_n_1</entry>
+ </row>
+ <row>
+ <entry>16</entry><entry>uint8_t</entry><entry>sat_5_id</entry>
+ </row>
+ <row>
+ <entry>17</entry><entry>uint8_t</entry><entry>sat_5_c_n_1</entry>
+ </row>
+ <row>
+ <entry>18</entry><entry>uint8_t</entry><entry>sat_6_id</entry>
+ </row>
+ <row>
+ <entry>19</entry><entry>uint8_t</entry><entry>sat_6_c_n_1</entry>
+ </row>
+ <row>
+ <entry>20</entry><entry>uint8_t</entry><entry>sat_7_id</entry>
+ </row>
+ <row>
+ <entry>21</entry><entry>uint8_t</entry><entry>sat_7_c_n_1</entry>
+ </row>
+ <row>
+ <entry>22</entry><entry>uint8_t</entry><entry>sat_8_id</entry>
+ </row>
+ <row>
+ <entry>23</entry><entry>uint8_t</entry><entry>sat_8_c_n_1</entry>
+ </row>
+ <row>
+ <entry>24</entry><entry>uint8_t</entry><entry>sat_9_id</entry>
+ </row>
+ <row>
+ <entry>25</entry><entry>uint8_t</entry><entry>sat_9_c_n_1</entry>
+ </row>
+ <row>
+ <entry>26</entry><entry>uint8_t</entry><entry>sat_10_id</entry>
+ </row>
+ <row>
+ <entry>27</entry><entry>uint8_t</entry><entry>sat_10_c_n_1</entry>
+ </row>
+ <row>
+ <entry>28</entry><entry>uint8_t</entry><entry>sat_11_id</entry>
+ </row>
+ <row>
+ <entry>29</entry><entry>uint8_t</entry><entry>sat_11_c_n_1</entry>
+ </row>
+ <row>
+ <entry>30</entry><entry>uin8_t</entry><entry>unused30</entry>
+ </row>
+ <row>
+ <entry>31</entry><entry>uin8_t</entry><entry>unused31</entry>
+ </row>
+ <row>
+ <entry>32</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </section>
+ </section>
+</article>
+
+<!--
+
+
+
+
+ Rethinking this (over IRC), and thinking about telemetry from a
+ companion board, it looks like 32 bytes per packet would be better (12
+ channels of A/D from telescience would require 24 bytes).
+
+ Packet type 0x06: GPS satellites
+ 1 packet per second.
+
+
+ TeleScience
+
+<entry>5</entry><entry>uint8_t</entry><entry>channels</entry>
+<entry>6</entry><entry>uint16_t</entry><entry>data[12]</entry>
+<entry>30</entry><entry>uint8_t</entry><entry>unused[2]</entry>
+<entry>32</entry>
+
+ [ 2-line signature. Click/Enter to show. ]
+ - -
+ keith.packard@intel.com
+ [ application/pgp-signature ]
+ Keith Packard <keithp@keithp.com> (Mon. 18:59) (me sent)
+ Subject: Re: New telemetry ideas
+ To: bdale@gag.com
+ Date: Mon, 27 Jun 2011 18:59:08 -0700
+
+ [ multipart/signed ]
+ [ text/plain ]
+ On Mon, 27 Jun 2011 14:25:00 -0700, Keith Packard <keithp@keithp.com> wrote:
+ Non-text part: multipart/signed
+
+ > Packet type 0x05: GPS location
+ > 1 packet per second
+ >
+ > 5 uint8_t flags
+
+ Let's add another field here:
+
+<entry>6</entry><entry>int16_t</entry><entry>gps_tick</entry><entry>tick when GPS data was received</entry>
+
+ That leaves a single byte unused
+-->
\ No newline at end of file
projects / fw / altos / commitdiff