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+<html xmlns="http://www.w3.org/1999/xhtml">
+<head>
+ <meta http-equiv="content-type" content="text/html; charset=iso-8859-1" />
+ <title>Village DTN Router - User Interface</title>
+ <meta name="generator" content="Amaya, see http://www.w3.org/Amaya/" />
+</head>
+
+<body>
+<h1>Village DTN Router - Hardware User Interface</h1>
+
+<p>stephen.farrell@cs.tcd.ie, 2010-05-27</p>
+
+<p>This document describes the external user interface of the village DTN
+router box. That is: how to interpret the contents displayed on the screen and
+how to turn the device on and off safely.</p>
+
+<p>The first thing to note is that users should only use the device as shown
+here - <strong>ONLY TRAINED STAFF SHOULD ATTEMPT OTHER ACTIONS</strong>, so
+please do not disturb cables, antennae or other external parts of the device.
+Any such tampering is likely to result in an non-functional village DTN router
+so please don't do it!</p>
+
+<p>Figure 1 shows a village DTN router deployed in Staloluokta in 2009.</p>
+
+<h2>Turning On and Off</h2>
+
+<p>The large switch at the side of the device is used to turn it on and off.
+The device requries approximately two minutes to fully boot and bring up all of
+the WiFi, mail and web services. <strong>PLEASE BE PATIENT - DO NOT CONSTANTLY
+SWITCH THE DEVICE ON AND OFF!</strong> Doing so could damage the device, in
+particular, the filesystems - such an error would be the equivalent of a
+hard-disk failure in a laptop.</p>
+
+<p>Figure 2 shows the ON/OFF switch in the "ON" position. </p>
+
+<p>Figure 3 shows the ON/OFF switch in the "OFF" position.</p>
+
+<p>Figure 4 shows a user switch the device to the "ON" position.</p>
+
+<p>That's all very simple so far, but its gets a little more complicated when
+we need to understand how the device manages its use of power.</p>
+
+<h2>Power Management</h2>
+
+<p>As a solar-powered device, the village DTN router must manage its power so
+as to conserve battery in case there is not sufficient sunlight to charge the
+batteries. We have implemented a power management module for the village DTN
+router with the following features:</p>
+<ul>
+ <li>When sufficient power is available and the device is operating normally,
+ it is in the "UP" state. In the "UP" state, all WiFi, mail and web services
+ are operating.</li>
+ <li>When power levels are lower, the device may switch to a standby mode of
+ operation for a short period (30 minutes) to allow some time for the
+ batteries to recharge, this is the "STANDBY-SHORT" state. In this state the
+ device uses much less power, but no services are available as the processor
+ in the device is asleep, just like a laptop in standby mode. After 30
+ minutes, the device will power up, and if power levels are sufficient will
+ change to the "UP" state.</li>
+ <li>If power levels fall further, the device will </li>
+</ul>
+
+<p></p>
+
+<p></p>
+</body>
+</html>