-<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>MicroPeak Owner's Manual</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book"><div class="titlepage"><div><div><h1 class="title"><a name="id
m3476640"></a>MicroPeak Owner's Manual</h1></div><div><h2 class="subtitle">A recording altimeter for hobby rocketry</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Keith</span> <span class="surname">Packard</span></h3></div></div><div><p class="copyright">Copyright © 2012 Bdale Garbee and Keith Packard</p></div><div><div class="legalnotice"><a name="idp48484960"></a><p>
+<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>MicroPeak Owner's Manual</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book"><div class="titlepage"><div><div><h1 class="title"><a name="id
p25652576"></a>MicroPeak Owner's Manual</h1></div><div><h2 class="subtitle">A recording altimeter for hobby rocketry</h2></div><div><div class="author"><h3 class="author"><span class="firstname">Keith</span> <span class="surname">Packard</span></h3></div></div><div><p class="copyright">Copyright © 2012 Bdale Garbee and Keith Packard</p></div><div><div class="legalnotice"><a name="idp52026128"></a><p>
This document is released under the terms of the
<a class="ulink" href="http://creativecommons.org/licenses/by-sa/3.0/" target="_top">
Creative Commons ShareAlike 3.0
Add documentation for the MicroPeak USB adapter board. Note
the switch to a Kalman filter for peak altitude
determination.
- </td></tr></table></div></div></div><hr></div><div class="dedication"><div class="titlepage"><div><div><h1 class="title"><a name="idp48368352"></a>Acknowledgements</h1></div></div></div><p>
+ </td></tr><tr><td align="left">Revision 1.3.2</td><td align="left">12 February 2014</td></tr><tr><td align="left" colspan="2">
+ Add a "Download" button to the main window, which makes it
+ quicker to access the download function. Update the data
+ download documentation to reflect the new MicroPeak USB
+ adapter design. Monitor data during download to let you see
+ if the USB connection is working at all by showing the
+ characters received from the MicroPeak USB adapter.
+ </td></tr></table></div></div></div><hr></div><div class="dedication"><div class="titlepage"><div><div><h1 class="title"><a name="idp52911408"></a>Acknowledgements</h1></div></div></div><p>
Thanks to John Lyngdal for suggesting that we build something like this.
</p><p>
Have fun using these products, and we hope to meet all of you
Keith Packard, KD7SQG<br>
NAR #88757, TRA #12200<br>
</p></div><p>
- </p></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="chapter"><a href="#idp
49397120">1. Quick Start Guide</a></span></dt><dt><span class="chapter"><a href="#idp49406608">2. Handling Precautions</a></span></dt><dt><span class="chapter"><a href="#idp48534496">3. The MicroPeak USB adapter</a></span></dt><dd><dl><dt><span class="section"><a href="#idp48535824">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp48538880">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp48544992">3. Analyzing MicroPeak Data</a></span></dt><dt><span class="section"><a href="#idp48550624">4. Configuring the MicroPeak application</a></span></dt></dl></dd><dt><span class="chapter"><a href="#idp48377088">4. Technical Information</a></span></dt><dd><dl><dt><span class="section"><a href="#idp48377760">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp48380368">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp48382720">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp48385504">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp48387904">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp48390656">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp55072352">7. MicroPeak Programming Interface</a></span></dt></dl></dd></dl></div><div class="list-of-tables"><p><b>List of Tables</b></p><dl><dt>4.1. <a href="#idp48392720">MicroPeak EEPROM Data Storage</a></dt></dl></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp49397120"></a>Chapter 1. Quick Start Guide</h1></div></div></div><p>
+ </p></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="chapter"><a href="#idp
52914048">1. Quick Start Guide</a></span></dt><dt><span class="chapter"><a href="#idp56709712">2. Handling Precautions</a></span></dt><dt><span class="chapter"><a href="#idp56714096">3. The MicroPeak USB adapter</a></span></dt><dd><dl><dt><span class="section"><a href="#idp56717648">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp56720736">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp52053600">3. Analyzing MicroPeak Data</a></span></dt><dd><dl><dt><span class="section"><a href="#idp52057088">3.1. MicroPeak Graphs</a></span></dt><dt><span class="section"><a href="#idp52060688">3.2. MicroPeak Flight Statistics</a></span></dt><dt><span class="section"><a href="#idp52064560">3.3. Raw Data</a></span></dt><dt><span class="section"><a href="#idp57543120">3.4. Configuring the Graph</a></span></dt></dl></dd><dt><span class="section"><a href="#idp57546656">4. Setting MicroPeak Preferences</a></span></dt></dl></dd><dt><span class="chapter"><a href="#idp57556640">4. Technical Information</a></span></dt><dd><dl><dt><span class="section"><a href="#idp57557312">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp57560064">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp57562416">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp57565200">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp57568176">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp57570928">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp57591264">7. MicroPeak Programming Interface</a></span></dt></dl></dd></dl></div><div class="list-of-tables"><p><b>List of Tables</b></p><dl><dt>4.1. <a href="#idp57573040">MicroPeak EEPROM Data Storage</a></dt></dl></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp52914048"></a>Chapter 1. Quick Start Guide</h1></div></div></div><p>
MicroPeak is designed to be easy to use. Requiring no external
components, flying takes just a few steps
</p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
open side of the carrier. Slip the carrier into the battery
holder with the positive (+) terminal facing away from the
circuit board.
- </p></li><li class="listitem"><p>
+ </p><
div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-back.jpg" width="405"></td></tr></table></div></div></li><li class="listitem"><p>
Install MicroPeak in your rocket. This can be as simple as
preparing a soft cushion of wadding inside a vented model payload
bay. Wherever you mount it, make sure you protect the
Recover the data. Turn MicroPeak off and then back on. MicroPeak
will blink out the maximum height for the last flight. Turn
MicroPeak back off to conserve battery power.
- </p></li></ul></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
49406608"></a>Chapter 2. Handling Precautions</h1></div></div></div><p>
+ </p></li></ul></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
56709712"></a>Chapter 2. Handling Precautions</h1></div></div></div><p>
All Altus Metrum products are sophisticated electronic devices.
When handled gently and properly installed in an air-frame, they
will deliver impressive results. However, as with all electronic
As with all other rocketry electronics, Altus Metrum altimeters must
be protected from exposure to corrosive motor exhaust and ejection
charge gasses.
- </p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
48534496"></a>Chapter 3. The MicroPeak USB adapter</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp48535824">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp48538880">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp48544992">3. Analyzing MicroPeak Data</a></span></dt><dt><span class="section"><a href="#idp48550624">4. Configuring the MicroPeak application</a></span></dt></dl></div><p>
+ </p></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
56714096"></a>Chapter 3. The MicroPeak USB adapter</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp56717648">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp56720736">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp52053600">3. Analyzing MicroPeak Data</a></span></dt><dd><dl><dt><span class="section"><a href="#idp52057088">3.1. MicroPeak Graphs</a></span></dt><dt><span class="section"><a href="#idp52060688">3.2. MicroPeak Flight Statistics</a></span></dt><dt><span class="section"><a href="#idp52064560">3.3. Raw Data</a></span></dt><dt><span class="section"><a href="#idp57543120">3.4. Configuring the Graph</a></span></dt></dl></dd><dt><span class="section"><a href="#idp57546656">4. Setting MicroPeak Preferences</a></span></dt></dl></div><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="MicroPeakUSB-2.0.jpg" width="405"></td></tr></table></div></div><p>
MicroPeak stores barometric pressure information for the first
48 seconds of the flight in on-board non-volatile memory. The
contents of this memory can be downloaded to a computer using
the MicroPeak USB adapter.
- </p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48535824"></a>1. Installing the MicroPeak software</h2></div></div></div><p>
+ </p><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
56717648"></a>1. Installing the MicroPeak software</h2></div></div></div><p>
The MicroPeak application runs on Linux, Mac OS X and
Windows. You can download the latest version from
<a class="ulink" href="http://altusmetrum.org/AltOS" target="_top">http://altusmetrum.org/AltOS</a>.
be installed. A compatible version of this driver is included
with the MicroPeak application, but you may want to download a
newer version from <a class="ulink" href="http://www.ftdichip.com/FTDrivers.htm" target="_top">http://www.ftdichip.com/FTDrivers.htm</a>.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48538880"></a>2. Downloading Micro Peak data</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
- Connect the MicroPeak USB adapter to a USB cable and plug it
- in to your computer.
- </p></li><li class="listitem"><p>
- Start the MicroPeak application, locate the File menu and
- select the Download entry.
- </p></li><li class="listitem"><p>
- The MicroPeak USB adapter has a small phototransistor on
- the end of the board furthest from the USB
- connector. Locate this and place the LED on the MicroPeak
- directly in contact with it. The MicroPeak LED and the
- MicroPeak USB adapter photo need to be touching—even a
- millimeters of space between them will reduce the light
- intensity from the LED enough that the phototransistor
- will not sense it. Turn on the MicroPeak board and adjust
- the position until the blue LED on the MicroPeak USB
- adapter blinks in time with the orange LED on the
- MicroPeak board.
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp56720736"></a>2. Downloading Micro Peak data</h2></div></div></div><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p>
+ Plug the MicroPeak USB adapter in to your computer.
</p></li><li class="listitem"><p>
+ Start the MicroPeak application.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="45"><tr><td><img src="micropeak-nofont.svg" width="45"></td></tr></table></div></div></li><li class="listitem"><p>
+ Click on the Download button at the top of the window.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-app.png" width="405"></td></tr></table></div></div></li><li class="listitem"><p>
+ Select from the listed devices. There will probably be
+ only one.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="207"><tr><td><img src="micropeak-device-dialog.png" width="207"></td></tr></table></div></div></li><li class="listitem"><p>
+ The application will now wait until it receives valid data
+ from the MicroPeak USB adapter.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="180"><tr><td><img src="micropeak-download.png" width="180"></td></tr></table></div></div><p>
+ The MicroPeak USB adapter has a small phototransistor
+ under the hole in the center of the box.
+ Locate this, turn on the MicroPeak and place the orange LED on the MicroPeak
+ directly inside the hole, resting the MicroPeak itself on
+ the box. You should see the blue LED on the MicroPeak USB
+ adapter blinking in time with the orange LED on the
+ MicroPeak board itself.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="MicroPeakUSB-2.0-inuse.jpg" width="405"></td></tr></table></div></div></li><li class="listitem"><p>
After the maximum flight height is reported, MicroPeak will
pause for a few seconds, blink the LED four times rapidly
and then send the data in one long blur on the LED. The
it will present the data in a graph and offer to save the
data to a file. If not, you can power cycle the MicroPeak
board and try again.
- </p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48544992"></a>3. Analyzing MicroPeak Data</h2></div></div></div><p>
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="207"><tr><td><img src="micropeak-save-dialog.png" width="207"></td></tr></table></div></div></li><li class="listitem"><p>
+ Once the data are saved, a graph will be displayed with
+ height, speed and acceleration values computed from the
+ recorded barometric pressure data. See the next section
+ for more details on that.
+ </p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp52053600"></a>3. Analyzing MicroPeak Data</h2></div></div></div><p>
The MicroPeak application can present flight data in the form
of a graph, a collection of computed statistics or in tabular
form.
eleven samples are used. These were chosen to provide
reasonably smooth speed and acceleration data, which would
otherwise be swamped with noise.
- </p><p>
- Under the Graph tab, the height, speed and acceleration values
- are displayed together. You can zoom in on the graph by
- clicking and dragging to sweep out an area of
- interest. Right-click on the plot to bring up a menu that will
- let you save, copy or print the graph.
- </p><p>
- The Statistics tab presents overall data from the flight. Note
- that the Maximum height value is taken from the minumum
- pressure captured in flight, and may be different from the
- apparant apogee value as the on-board data are sampled twice
- as fast as the recorded values, or because the true apogee
- occurred after the on-board memory was full. Each value is
- presented in several units as appropriate.
- </p><p>
- A table consisting of the both the raw barometric pressure
- data and values computed from that for each recorded time.
</p><p>
The File menu has operations to open existing flight logs,
Download new data from MicroPeak, Save a copy of the flight
Data tab) to a file, change the application Preferences, Close
the current window or close all windows and Exit the
application.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48550624"></a>4. Configuring the MicroPeak application</h2></div></div></div><p>
+ </p><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp52057088"></a>3.1. MicroPeak Graphs</h3></div></div></div><p>
+ Under the Graph tab, the height, speed and acceleration values
+ are displayed together. You can zoom in on the graph by
+ clicking and dragging to sweep out an area of
+ interest. Right-click on the plot to bring up a menu that will
+ let you save, copy or print the graph.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-graph.png" width="405"></td></tr></table></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp52060688"></a>3.2. MicroPeak Flight Statistics</h3></div></div></div><p>
+ The Statistics tab presents overall data from the flight. Note
+ that the Maximum height value is taken from the minumum
+ pressure captured in flight, and may be different from the
+ apparant apogee value as the on-board data are sampled twice
+ as fast as the recorded values, or because the true apogee
+ occurred after the on-board memory was full. Each value is
+ presented in several units as appropriate.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-statistics.png" width="405"></td></tr></table></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp52064560"></a>3.3. Raw Data</h3></div></div></div><p>
+ A table consisting of the both the raw barometric pressure
+ data and values computed from that for each recorded time.
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-raw-data.png" width="405"></td></tr></table></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a name="idp57543120"></a>3.4. Configuring the Graph</h3></div></div></div><p>
+ This selects which graph elements to show, and lets you
+ switch between metric and imperial units
+ </p><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="405"><tr><td><img src="micropeak-graph-configure.png" width="405"></td></tr></table></div></div></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp57546656"></a>4. Setting MicroPeak Preferences</h2></div></div></div><div class="informalfigure"><div class="mediaobject"><table border="0" summary="manufactured viewport for HTML img" style="cellpadding: 0; cellspacing: 0;" width="162"><tr><td><img src="micropeak-preferences.png" width="162"></td></tr></table></div></div><p>
The MicroPeak application has a few user settings which are
configured through the Preferences dialog, which can be
accessed from the File menu.
Note that MicroPeak shares a subset of the AltosUI
preferences, so if you use both of these applications, change
in one application will affect the other.
- </p></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
48377088"></a>Chapter 4. Technical Information</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp48377760">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp48380368">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp48382720">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp48385504">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp48387904">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp48390656">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp55072352">7. MicroPeak Programming Interface</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48377760"></a>1. Barometric Sensor</h2></div></div></div><p>
+ </p></div></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp
57556640"></a>Chapter 4. Technical Information</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="section"><a href="#idp57557312">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp57560064">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp57562416">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp57565200">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp57568176">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp57570928">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp57591264">7. MicroPeak Programming Interface</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp57557312"></a>1. Barometric Sensor</h2></div></div></div><p>
MicroPeak uses the Measurement Specialties MS5607 sensor. This
has a range of 120kPa to 1kPa with an absolute accuracy of
150Pa and a resolution of 2.4Pa.
60cm (24in) at 10000m (33000 feet).
</p><p>
Ground pressure is computed from an average of 16 samples,
- taken while the altimeter is at rest. Flight pressure is
- computed from a Kalman filter designed to smooth out any minor
- noise in the sensor values.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48380368"></a>2. Micro-controller</h2></div></div></div><p>
+ taken while the altimeter is at rest. The flight pressure used to
+ report maximum height is computed from a Kalman filter
+ designed to smooth out any minor noise in the sensor
+ values. The flight pressure recorded to non-volatile storage
+ is unfiltered, coming directly from the pressure sensor.
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp57560064"></a>2. Micro-controller</h2></div></div></div><p>
MicroPeak uses an Atmel ATtiny85 micro-controller. This tiny
CPU contains 8kB of flash for the application, 512B of RAM for
temporary data storage and 512B of EEPROM for non-volatile
this mode, the chip consumes only .1μA of power. MicroPeak
uses this mode once the flight has ended to preserve battery
power.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48382720"></a>3. Lithium Battery</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
57562416"></a>3. Lithium Battery</h2></div></div></div><p>
The CR1025 battery used by MicroPeak holds 30mAh of power,
which is sufficient to run for over 40 hours. Because
MicroPeak powers down on landing, run time includes only time
battery with MicroPeak. If so, many stores carry CR1025
batteries as they are commonly used in small electronic
devices such as flash lights.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48385504"></a>4. Atmospheric Model</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
57565200"></a>4. Atmospheric Model</h2></div></div></div><p>
MicroPeak contains a fixed atmospheric model which is used to
convert barometric pressure into altitude. The model was
- converted into a 469-element piece wise linear approximation
+ converted into a 469-element piece-wise linear approximation
which is then used to compute the altitude of the ground and
apogee. The difference between these represents the maximum
height of the flight.
</p><p>
The model assumes a particular set of atmospheric conditions,
- which while a reasonable average cannot represent the changing
+ which, while a reasonable average, cannot represent the changing
nature of the real atmosphere. Fortunately, for flights
reasonably close to the ground, the effect of this global
inaccuracy are largely canceled out when the computed ground
altitude is subtracted from the computed apogee altitude, so
the resulting height is more accurate than either the ground
or apogee altitudes.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp48387904"></a>5. Mechanical Considerations</h2></div></div></div><p>
+ </p><p>
+ Because the raw pressure data is recorded to non-volatile
+ storage, you can use that, along with a more sophisticated
+ atmospheric model, to compute your own altitude values.
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp57568176"></a>5. Mechanical Considerations</h2></div></div></div><p>
MicroPeak is designed to be rugged enough for typical rocketry
applications. It contains two moving parts, the battery holder
and the power switch, which were selected for their
any direction. Because it is a sliding switch, orienting the
switch perpendicular to the direction of rocket travel will
serve to further protect the switch from launch forces.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48390656"></a>6. On-board data storage</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
57570928"></a>6. On-board data storage</h2></div></div></div><p>
The ATtiny85 has 512 bytes of non-volatile storage, separate
from the code storage memory. The MicroPeak firmware uses this
to store information about the last completed
</p><p>
In addition to the data used to present the height of the last
flight, MicroPeak also stores barometric information sampled
- at regular intervals during the flight. This information can
- be extracted from MicroPeak through any AVR programming
+ at regular intervals during the flight. This is the
+ information captured with the MicroPeak USB adapter. It can
+ also be read from MicroPeak through any AVR programming
tool.
- </p><div class="table"><a name="idp
48392720"></a><p class="title"><b>Table 4.1. MicroPeak EEPROM Data Storage</b></p><div class="table-contents"><table summary="MicroPeak EEPROM Data Storage" border="1"><colgroup><col align="center" class="Address"><col align="center" class="Size (bytes)"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Address</th><th align="center">Size (bytes)</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0x000</td><td align="center">4</td><td align="left">Average ground pressure (Pa)</td></tr><tr><td align="center">0x004</td><td align="center">4</td><td align="left">Minimum flight pressure (Pa)</td></tr><tr><td align="center">0x008</td><td align="center">2</td><td align="left">Number of in-flight samples</td></tr><tr><td align="center">0x00a … 0x1fe</td><td align="center">2</td><td align="left">Instantaneous flight pressure (Pa) low 16 bits</td></tr></tbody></table></div></div><br class="table-break"><p>
+ </p><div class="table"><a name="idp
57573040"></a><p class="title"><b>Table 4.1. MicroPeak EEPROM Data Storage</b></p><div class="table-contents"><table summary="MicroPeak EEPROM Data Storage" border="1"><colgroup><col align="center" class="Address"><col align="center" class="Size (bytes)"><col align="left" class="Description"></colgroup><thead><tr><th align="center">Address</th><th align="center">Size (bytes)</th><th align="center">Description</th></tr></thead><tbody><tr><td align="center">0x000</td><td align="center">4</td><td align="left">Average ground pressure (Pa)</td></tr><tr><td align="center">0x004</td><td align="center">4</td><td align="left">Minimum flight pressure (Pa)</td></tr><tr><td align="center">0x008</td><td align="center">2</td><td align="left">Number of in-flight samples</td></tr><tr><td align="center">0x00a … 0x1fe</td><td align="center">2</td><td align="left">Instantaneous flight pressure (Pa) low 16 bits</td></tr></tbody></table></div></div><br class="table-break"><p>
All EEPROM data are stored least-significant byte first. The
instantaneous flight pressure data are stored without the
upper 16 bits of data. The upper bits can be reconstructed
25°C. So, you can count on the pressure data being accurate,
but speed or acceleration data computed from this will be
limited by the accuracy of this clock.
- </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp5
5072352"></a>7. MicroPeak Programming Interface</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp5
7591264"></a>7. MicroPeak Programming Interface</h2></div></div></div><p>
MicroPeak exposes a standard 6-pin AVR programming interface,
but not using the usual 2x3 array of pins on 0.1"
centers. Instead, there is a single row of tiny 0.60mm ×
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