-<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="idm
6245264"></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="idp48058064"></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="idm
3476640"></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>
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="idp4
7885280"></a>Acknowledgements</h1></div></div></div><p>
+ </td></tr></table></div></div></div><hr></div><div class="dedication"><div class="titlepage"><div><div><h1 class="title"><a name="idp4
8368352"></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="#idp4
8960176">1. Quick Start Guide</a></span></dt><dt><span class="chapter"><a href="#idp48969664">2. Handling Precautions</a></span></dt><dt><span class="chapter"><a href="#idp53493376">3. The MicroPeak USB adapter</a></span></dt><dd><dl><dt><span class="section"><a href="#idp53494704">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp53497792">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp53503952">3. Analyzing MicroPeak Data</a></span></dt><dt><span class="section"><a href="#idp47886320">4. Configuring the MicroPeak application</a></span></dt></dl></dd><dt><span class="chapter"><a href="#idp47894112">4. Technical Information</a></span></dt><dd><dl><dt><span class="section"><a href="#idp47894784">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp47897392">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp47899744">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp47902528">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp47904928">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp47907680">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp54636384">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="#idp47909744">MicroPeak EEPROM Data Storage</a></dt></dl></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp48960176"></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="#idp4
9397120">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>
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>
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="idp4
8969664"></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="idp4
9406608"></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
53493376"></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="#idp53494704">1. Installing the MicroPeak software</a></span></dt><dt><span class="section"><a href="#idp53497792">2. Downloading Micro Peak data</a></span></dt><dt><span class="section"><a href="#idp53503952">3. Analyzing MicroPeak Data</a></span></dt><dt><span class="section"><a href="#idp47886320">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
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>
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
53494704"></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
48535824"></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="idp
53497792"></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>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48538880"></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>
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="idp
53503952"></a>3. Analyzing MicroPeak Data</h2></div></div></div><p>
+ </p></li></ul></div></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp
48544992"></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.
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="idp4
7886320"></a>4. Configuring the MicroPeak application</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp4
8550624"></a>4. Configuring the MicroPeak application</h2></div></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="idp4
7894112"></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="#idp47894784">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp47897392">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp47899744">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp47902528">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp47904928">5. Mechanical Considerations</a></span></dt><dt><span class="section"><a href="#idp47907680">6. On-board data storage</a></span></dt><dt><span class="section"><a href="#idp54636384">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="idp47894784"></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="idp4
8377088"></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>
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.
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="idp4
7897392"></a>2. Micro-controller</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp4
8380368"></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="idp4
7899744"></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="idp4
8382720"></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="idp4
7902528"></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="idp4
8385504"></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
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="idp4
7904928"></a>5. Mechanical Considerations</h2></div></div></div><p>
+ </p></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp4
8387904"></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="idp4
7907680"></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="idp4
8390656"></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
at regular intervals during the flight. This information can
be extracted from MicroPeak through any AVR programming
tool.
- </p><div class="table"><a name="idp4
7909744"></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="idp4
8392720"></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
4636384"></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
5072352"></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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