<?xml version="1.0" encoding="utf-8" ?>
-<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+<!DOCTYPE article PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd">
<article>
The Companion Port provides two different functions:
<itemizedlist>
<listitem>
+ <para>
Power. Both battery-level and 3.3V regulated power are
available. Note that the amount of regulated power is not
huge; TeleMetrum contains a 150mA regulator and uses, at
peak, about 120mA or so. For applications needing more than
a few dozen mA, placing a separate regulator on them and
using the battery for power is probably a good idea.
+ </para>
</listitem>
<listitem>
+ <para>
SPI. The flight computer operates as a SPI master, using
a protocol defined in this document. Companion boards
provide a matching SPI slave implementation which supplies
telemetry information for the radio downlink during flight
+ </para>
</listitem>
</itemizedlist>
</para>
</section>
<section>
<title>SPI Message Formats</title>
+ <para>
This section first defines the command message format sent from
the flight computer to the companion board, and then the various
reply message formats for each type of command message.
+ </para>
<section>
<title>Command Message</title>
<table frame='all'>