-<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 V1.76.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="book" title="MicroPeak Owner's Manual"><div class="titlepage"><div><div><h1 class="title"><a name="idm14762280"></a>MicroPeak Owner's Manual</h1></div><div><h2 class="subtitle">A peak-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" title="Legal Notice"><a name="idp172816"></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
- </a>
- license.
- </p></div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr><tr><td align="left">Revision 0.1</td><td align="left">29 October 2012</td></tr><tr><td align="left" colspan="2">
- Initial release with preliminary hardware.
- </td></tr></table></div></div></div><hr></div><div class="acknowledgements" title="Acknowledgements"><div class="titlepage"><div><div><h2 class="title"><a name="idp174776"></a>Acknowledgements</h2></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
- out on the rocket flight line somewhere.
- </p><div class="literallayout"><p><br>
-Bdale Garbee, KB0G<br>
-NAR #87103, TRA #12201<br>
-<br>
-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><dt><span class="chapter"><a href="#idp176024">1. Quick Start Guide</a></span></dt><dt><span class="chapter"><a href="#idp1555544">2. Handling Precautions</a></span></dt><dt><span class="chapter"><a href="#idp1561440">3. Technical Information</a></span></dt><dd><dl><dt><span class="section"><a href="#idp3211240">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp1961960">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp2901888">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp1674792">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp1421872">5. Mechanical Considerations</a></span></dt></dl></dd></dl></div><div class="chapter" title="Chapter 1. Quick Start Guide"><div class="titlepage"><div><div><h2 class="title"><a name="idp176024"></a>Chapter 1. Quick Start Guide</h2></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" type="disc"><li class="listitem"><p>
- Install the battery. Fit a CR1025 battery into the plastic
- carrier. The positive (+) terminal should be towards the more
- 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>
- 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
- barometric sensor from corrosive ejection gasses as those
- will damage the sensor.
- </p></li><li class="listitem"><p>
- Turn MicroPeak on. Slide the switch so that the actuator
- covers the '1' printed on the board. MicroPeak will report
- the maximum height of the last flight in decimeters using a
- sequence of flashes on the LED. A sequence of short flashes
- indicates one digit. A single long flash indicates zero. The
- height is reported in decimeters, so the last digit will be
- tenths of a meter. For example, if MicroPeak reports 5 4 4
- 3, then the maximum height of the last flight was 544.3m, or
- 1786 feet.
- </p></li><li class="listitem"><p>
- Finish preparing the rocket for flight. After the
- previous flight data have been reported, MicroPeak waits for
- 30 seconds before starting to check for launch. This gives
- you time to finish assembling the rocket. As those
- activities might cause pressure changes inside the airframe,
- MicroPeak might accidentally detect boost. If you need to do
- anything to the airframe after the 30 second window passes,
- make sure to be careful not to disturb the altimeter. The
- LED will remain dark during the 30 second delay, but after
- that, it will start blinking once every 3 seconds.
- </p></li><li class="listitem"><p>
- Fly the rocket. Once the rocket passes about 10m in height
- (32 feet), the micro-controller will record the ground
- pressure and track the pressure seen during the flight. In
- this mode, the LED flickers rapidly. When the rocket lands,
- and the pressure stabilizes, the micro-controller will record
- the minimum pressure pressure experienced during the flight,
- compute the height represented by the difference in air
- pressure and blink that value out on the LED. After that,
- MicroPeak powers down to conserve battery power.
- </p></li><li class="listitem"><p>
- Recover the data. Turn MicroPeak off for a couple of seconds
- (to discharge the capacitors) 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" title="Chapter 2. Handling Precautions"><div class="titlepage"><div><div><h2 class="title"><a name="idp1555544"></a>Chapter 2. Handling Precautions</h2></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
- devices, there are some precautions you must take.
- </p><p>
- The CR1025 Lithium batteries have an
- extraordinary power density. This is great because we can fly with
- much less battery mass... but if they are punctured
- or their contacts are allowed to short, they can and will release their
- energy very rapidly!
- Thus we recommend that you take some care when handling MicroPeak
- to keep conductive material from coming in contact with the exposed metal elements.
- </p><p>
- The barometric sensors used in MicroPeak is
- sensitive to sunlight. Please consider this when
- designing an installation, for example, in an air-frame with a
- see-through plastic payload bay. Many model rockets with payload bays
- use clear plastic for the payload bay. Replacing these with an opaque
- cardboard tube, painting them, or wrapping them with a layer of masking
- tape are all reasonable approaches to keep the sensor out of direct
- sunlight.
- </p><p>
- The barometric sensor sampling ports must be able to "breathe",
- both by not being covered by foam or tape or other materials that might
- directly block the hole on the top of the sensor, and also by having a
- suitable static vent to outside air.
- </p><p>
- 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" title="Chapter 3. Technical Information"><div class="titlepage"><div><div><h2 class="title"><a name="idp1561440"></a>Chapter 3. Technical Information</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="section"><a href="#idp3211240">1. Barometric Sensor</a></span></dt><dt><span class="section"><a href="#idp1961960">2. Micro-controller</a></span></dt><dt><span class="section"><a href="#idp2901888">3. Lithium Battery</a></span></dt><dt><span class="section"><a href="#idp1674792">4. Atmospheric Model</a></span></dt><dt><span class="section"><a href="#idp1421872">5. Mechanical Considerations</a></span></dt></dl></div><div class="section" title="1. Barometric Sensor"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp3211240"></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.
- </p><p>
- The pressure range corresponds roughly to an altitude range of
- -1500m (-4900 feet) to 31000m (102000 feet), while the
- resolution is approximately 20cm (8 inches) near sea level and
- 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 an exponential IIR filter designed to smooth out
- transients caused by mechanical stress on the barometer.
- </p></div><div class="section" title="2. Micro-controller"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1961960"></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
- storage of previous flight data.
- </p><p>
- The ATtiny85 has a low-power mode which turns off all of the
- clocks and powers down most of the internal components. In
- 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" title="3. Lithium Battery"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp2901888"></a>3. Lithium Battery</h2></div></div></div><p>
- The CR1025 battery used by MicroPeak holes 30mAh of power,
- which is sufficient to run for over 15 hours. Because
- MicroPeak powers down on landing, run time includes only time
- sitting on the launch pad or during flight.
- </p><p>
- The large positive terminal (+) is usually marked, while the
- smaller negative terminal is not. Make sure you install the
- battery with the positive terminal facing away from the
- circuit board where it will be in contact with the metal
- battery holder. A small pad on the circuit board makes contact
- with the negative battery terminal.
- </p><p>
- Shipping restrictions prevent us from including a CR1025
- battery with MicroPeak. Many stores carry CR1025 batteries as
- they are commonly used in small electronic devices such as
- flash lights.
- </p></div><div class="section" title="4. Atmospheric Model"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1674792"></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
- 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
- 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" title="5. Mechanical Considerations"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="idp1421872"></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
- ruggedness.
- </p><p>
- The MicroPeak battery holder is designed to withstand impact
- up to 150g without breaking contact (or, worse yet, causing
- the battery to fall out). That means it should stand up to
- almost any launch you care to try, and should withstand fairly
- rough landings.
- </p><p>
- The power switch is designed to withstand up to 50g forces in
- 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></div></body></html>
+<!DOCTYPE html>
+<html lang="en">
+<head>
+<meta charset="UTF-8">
+<meta http-equiv="X-UA-Compatible" content="IE=edge">
+<meta name="viewport" content="width=device-width, initial-scale=1.0">
+<meta name="generator" content="Asciidoctor 2.0.10">
+<meta name="author" content="Keith Packard, Bdale Garbee">
+<meta name="copyright" content="Bdale Garbee and Keith Packard 2020">
+<title>MicroPeak Owner’s Manual</title>
+<link rel="stylesheet" href="./am.css">
+</head>
+<body class="book">
+<div id="header">
+<h1>MicroPeak Owner’s Manual</h1>
+<div class="details">
+<span id="author" class="author">Keith Packard</span><br>
+<span id="email" class="email"><a href="mailto:keithp@keithp.com">keithp@keithp.com</a></span><br>
+<span id="author2" class="author">Bdale Garbee</span><br>
+<span id="email2" class="email"><a href="mailto:bdale@gag.com">bdale@gag.com</a></span><br>
+<span id="revnumber">version v1.9.2,</span>
+<span id="revdate">26 Feb 2020</span>
+</div>
+<div id="toc" class="toc">
+<div id="toctitle">Table of Contents</div>
+<ul class="sectlevel1">
+<li><a href="#_license">License</a></li>
+<li><a href="#_acknowledgements">Acknowledgements</a></li>
+<li><a href="#_using_micropeak">1. Using MicroPeak</a></li>
+<li><a href="#_the_micropeak_usb_adapter">2. The MicroPeak USB adapter</a>
+<ul class="sectlevel2">
+<li><a href="#_installing_the_micropeak_software">2.1. Installing the MicroPeak software</a></li>
+<li><a href="#_downloading_micro_peak_data">2.2. Downloading Micro Peak data</a></li>
+<li><a href="#_analyzing_micropeak_data">2.3. Analyzing MicroPeak Data</a></li>
+<li><a href="#_setting_micropeak_preferences">2.4. Setting MicroPeak Preferences</a></li>
+</ul>
+</li>
+<li><a href="#_protecting_micropeak_from_sunlight">3. Protecting MicroPeak from Sunlight</a></li>
+<li><a href="#_handling_precautions">Appendix A: Handling Precautions</a></li>
+<li><a href="#_technical_information">Appendix B: Technical Information</a>
+<ul class="sectlevel2">
+<li><a href="#_barometric_sensor">B.1. Barometric Sensor</a></li>
+<li><a href="#_micro_controller">B.2. Micro-controller</a></li>
+<li><a href="#_lithium_battery">B.3. Lithium Battery</a></li>
+<li><a href="#_atmospheric_model">B.4. Atmospheric Model</a></li>
+<li><a href="#_mechanical_considerations">B.5. Mechanical Considerations</a></li>
+<li><a href="#_micropeak_programming_interface">B.6. MicroPeak Programming Interface</a></li>
+</ul>
+</li>
+<li><a href="#_on_board_data_storage">Appendix C: On-board data storage</a></li>
+</ul>
+</div>
+</div>
+<div id="content">
+<div id="preamble">
+<div class="sectionbody">
+<div id="logo" class="imageblock">
+<div class="content">
+<a class="image" href="https://altusmetrum.org"><img src="altusmetrum-oneline.svg" alt="Altus Metrum"></a>
+</div>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_license">License</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<p>Copyright © 2018 Bdale Garbee and Keith Packard</p>
+</div>
+<div class="paragraph">
+<p>This document is released under the terms of the <a href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons ShareAlike 3.0 License</a></p>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_acknowledgements">Acknowledgements</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<p>Thanks to John Lyngdal for suggesting that we build something
+like this.</p>
+</div>
+<div class="paragraph">
+<p>Have fun using these products, and we hope to meet all of you
+out on the rocket flight line somewhere.</p>
+</div>
+<div class="verseblock">
+<pre class="content">Bdale Garbee, KB0G
+NAR #87103, TRA #12201</pre>
+</div>
+<div class="verseblock">
+<pre class="content">Keith Packard, KD7SQG
+NAR #88757, TRA #12200</pre>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_using_micropeak">1. Using MicroPeak</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<p>MicroPeak is designed to be easy to use. Requiring no external
+components, flying takes just a few steps</p>
+</div>
+<div class="dlist">
+<dl>
+<dt class="hdlist1">Install the battery</dt>
+<dd>
+<p>Fit a CR1025 battery into the plastic carrier. The positive
+(+) terminal should be towards the more open side of the
+carrier. Slip the carrier into the battery holder with the
+positive (+) terminal facing away from the circuit board.</p>
+</dd>
+</dl>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-back.jpg" alt="micropeak back" width="430">
+</div>
+<div class="title">Figure 1. MicroPeak and Battery</div>
+</div>
+<div class="dlist">
+<dl>
+<dt class="hdlist1">Install MicroPeak in your rocket</dt>
+<dd>
+<p>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 barometric sensor from corrosive
+ejection gasses as those will damage the sensor, and shield
+it from light as that can cause incorrect sensor readings.</p>
+</dd>
+<dt class="hdlist1">Turn MicroPeak on</dt>
+<dd>
+<p>Slide the switch so that the actuator covers the '1' printed
+on the board. MicroPeak will report the maximum height of
+the last flight in decimeters using a sequence of flashes on
+the LED. A sequence of short flashes indicates one digit. A
+single long flash indicates zero. The height is reported in
+decimeters, so the last digit will be tenths of a meter. For
+example, if MicroPeak reports 5 4 4 3, then the maximum
+height of the last flight was 544.3m, or 1786 feet.</p>
+</dd>
+<dt class="hdlist1">Finish preparing the rocket for flight</dt>
+<dd>
+<p>After the previous flight data have been reported, MicroPeak
+waits for one minute before starting to check for
+launch. This gives you time to finish assembling the
+rocket. As those activities might cause pressure changes
+inside the airframe, MicroPeak might accidentally detect
+boost. If you need to do anything to the airframe after the
+one minute window passes, make sure to be careful not to
+disturb the altimeter. The LED will remain dark during the
+one minute delay, but after that, it will start blinking
+once every 3 seconds.</p>
+</dd>
+<dt class="hdlist1">Fly the rocket</dt>
+<dd>
+<p>Once the rocket passes about 30m in height (100 feet), the
+micro-controller will record the ground pressure and track
+the pressure seen during the flight. In this mode, the LED
+flickers rapidly. When the rocket lands, and the pressure
+stabilizes, the micro-controller will record the minimum
+pressure pressure experienced during the flight, compute the
+height represented by the difference in air pressure and
+blink that value out on the LED. After that, MicroPeak
+powers down to conserve battery power.</p>
+</dd>
+<dt class="hdlist1">Recover the data</dt>
+<dd>
+<p>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>
+</dd>
+</dl>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_the_micropeak_usb_adapter">2. The MicroPeak USB adapter</h2>
+<div class="sectionbody">
+<div class="imageblock text-center">
+<div class="content">
+<img src="MicroPeakUSB-2.0.jpg" alt="MicroPeakUSB 2.0" width="430">
+</div>
+<div class="title">Figure 2. MicroPeak USB Adapter</div>
+</div>
+<div class="paragraph">
+<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>
+<div class="sect2">
+<h3 id="_installing_the_micropeak_software">2.1. Installing the MicroPeak software</h3>
+<div class="paragraph">
+<p>The MicroPeak application runs on Linux, Mac OS X and
+Windows. You can download the latest version from
+<a href="http://altusmetrum.org/MicroPeak" class="bare">http://altusmetrum.org/MicroPeak</a></p>
+</div>
+<div class="paragraph">
+<p>On Mac OS X and Windows, the FTDI USB device driver
+needs to 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 href="http://www.ftdichip.com/FTDrivers.htm" class="bare">http://www.ftdichip.com/FTDrivers.htm</a></p>
+</div>
+</div>
+<div class="sect2">
+<h3 id="_downloading_micro_peak_data">2.2. Downloading Micro Peak data</h3>
+<div class="ulist">
+<ul>
+<li>
+<p>Plug the MicroPeak USB adapter in to your computer.</p>
+</li>
+<li>
+<p>Start the MicroPeak application.</p>
+</li>
+</ul>
+</div>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-nofont.svg" alt="micropeak nofont" width="50">
+</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<p>Click on the Download button at the top of the
+window.</p>
+</li>
+</ul>
+</div>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-app.png" alt="micropeak app" width="430">
+</div>
+<div class="title">Figure 3. MicroPeak Application</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<p>Select from the listed devices. There will probably
+be only one.</p>
+</li>
+</ul>
+</div>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-device-dialog.png" alt="micropeak device dialog" width="220">
+</div>
+<div class="title">Figure 4. MicroPeak Device Dialog</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<p>The application will now wait until it receives
+valid data from the MicroPeak USB adapter.</p>
+</li>
+</ul>
+</div>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-download.png" alt="micropeak download" width="200">
+</div>
+<div class="title">Figure 5. MicroPeak Download Dialog</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<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>
+</li>
+</ul>
+</div>
+<div class="imageblock text-center">
+<div class="content">
+<img src="MicroPeakUSB-2.0-inuse.jpg" alt="MicroPeakUSB 2.0 inuse" width="430">
+</div>
+<div class="title">Figure 6. MicroPeak Downloading</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<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 MicroPeak application
+should receive the data. When it does, 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 class="imageblock text-center">
+<div class="content">
+<img src="micropeak-save-dialog.png" alt="micropeak save dialog" width="220">
+</div>
+<div class="title">Figure 7. MicroPeak Save Dialog</div>
+</div>
+<div class="ulist">
+<ul>
+<li>
+<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
+<<_analyzing_micropeak_data> for more details on that.</p>
+</li>
+</ul>
+</div>
+</div>
+<div class="sect2">
+<h3 id="_analyzing_micropeak_data">2.3. Analyzing MicroPeak Data</h3>
+<div class="paragraph">
+<p>The MicroPeak application can present flight data in
+the form of a graph, a collection of computed
+statistics or in tabular form.</p>
+</div>
+<div class="paragraph">
+<p>MicroPeak collects raw barometric pressure data which
+is then used to compute the remaining data. Altitude
+is computed through a standard atmospheric
+model. Absolute error in this data will be affected by
+local atmospheric conditions. Fortunately, these
+errors tend to mostly cancel out, so the error in the
+height computation is much smaller than the error in
+altitude would be.</p>
+</div>
+<div class="paragraph">
+<p>Speed and acceleration are computed by first smoothing
+the height data with a Gaussian window averaging
+filter. For speed data, this average uses seven
+samples. For acceleration data, eleven samples are
+used. These were chosen to provide reasonably smooth
+speed and acceleration data, which would otherwise be
+swamped with noise.</p>
+</div>
+<div class="paragraph">
+<p>The File menu has operations to open existing flight
+logs, Download new data from MicroPeak, Save a copy of
+the flight log to a new file, Export the tabular data
+(as seen in the Raw 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="sect3">
+<h4 id="_micropeak_graphs">2.3.1. MicroPeak Graphs</h4>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-graph.png" alt="micropeak graph" width="430">
+</div>
+<div class="title">Figure 8. MicroPeak Graph</div>
+</div>
+<div class="paragraph">
+<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>
+</div>
+<div class="sect3">
+<h4 id="_micropeak_flight_statistics">2.3.2. MicroPeak Flight Statistics</h4>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-statistics.png" alt="micropeak statistics" width="430">
+</div>
+<div class="title">Figure 9. MicroPeak Flight Statistics</div>
+</div>
+<div class="paragraph">
+<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>
+</div>
+<div class="sect3">
+<h4 id="_raw_flight_data">2.3.3. Raw Flight Data</h4>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-raw-data.png" alt="micropeak raw data" width="430">
+</div>
+<div class="title">Figure 10. MicroPeak Raw Flight Data</div>
+</div>
+<div class="paragraph">
+<p>A table consisting of the both the raw barometric pressure
+data and values computed from that for each recorded time.</p>
+</div>
+</div>
+<div class="sect3">
+<h4 id="_configuring_the_graph">2.3.4. Configuring the Graph</h4>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-graph-configure.png" alt="micropeak graph configure" width="430">
+</div>
+<div class="title">Figure 11. MicroPeak Graph Configuration</div>
+</div>
+<div class="paragraph">
+<p>This selects which graph elements to show, and lets you
+switch between metric and imperial units</p>
+</div>
+</div>
+</div>
+<div class="sect2">
+<h3 id="_setting_micropeak_preferences">2.4. Setting MicroPeak Preferences</h3>
+<div class="imageblock text-center">
+<div class="content">
+<img src="micropeak-preferences.png" alt="micropeak preferences" width="170">
+</div>
+<div class="title">Figure 12. MicroPeak Preferences</div>
+</div>
+<div class="paragraph">
+<p>The MicroPeak application has a few user settings which are
+configured through the Preferences dialog, which can be
+accessed from the File menu.</p>
+</div>
+<div class="dlist">
+<dl>
+<dt class="hdlist1">Log Directory</dt>
+<dd>
+<p>The Log Directory is where flight data will be
+saved to and loaded from by default. Of
+course, you can always navigate to other
+directories in the file chooser windows, this
+setting is just the starting point.</p>
+</dd>
+<dt class="hdlist1">Imperial Units</dt>
+<dd>
+<p>If you prefer to see your graph data in feet
+and miles per hour instead of meters and
+meters per second, you can select Imperial
+Units.</p>
+</dd>
+<dt class="hdlist1">Serial Debug</dt>
+<dd>
+<p>To see what data is actually arriving over the
+serial port, start the MicroPeak application
+from a command prompt and select the Serial
+Debug option. This can be useful in debugging
+serial communication problems, but most people
+need never choose this.</p>
+</dd>
+<dt class="hdlist1">Font Size</dt>
+<dd>
+<p>You can adjust the size of the text in the
+Statistics tab by changing the Font size
+preference. There are three settings, with
+luck one will both fit on your screen and
+provide readable values.</p>
+</dd>
+<dt class="hdlist1">Look & Feel</dt>
+<dd>
+<p>The Look & feel menu shows a list of available
+application appearance choices. By default,
+the MicroPeak application tries to blend in
+with other applications, but you may choose
+some other appearance if you like.</p>
+</dd>
+</dl>
+</div>
+<div class="paragraph">
+<p>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>
+</div>
+<div class="sect1">
+<h2 id="_protecting_micropeak_from_sunlight">3. Protecting MicroPeak from Sunlight</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<p>The MS5607 barometric sensor is sensitive to direct light. When light
+shines through the holes in the cover to the components inside, the
+reported pressure can vary wildly from the actual pressure. This
+causes the reported altitude to have errors of thousands of
+feet.</p>
+</div>
+<div class="paragraph">
+<p>MicroPeak should be installed in an opaque compartment in the airframe
+and not subjected to sunlight. Alternatively, a small piece of
+adhesive-backed open-cell foam can be attached to the device so that
+it covers the barometric sensor and protects it from direct light.</p>
+</div>
+<div class="paragraph">
+<p>Here’s what happens when MicroPeak is exposed to sunlight. At apogee,
+I exposed MicroPeak to varying amounts of sunlight and you can see the
+wild swings in altitude resulting from that:</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-flight-nofoam.png" alt="micropeak flight nofoam" width="430">
+</div>
+<div class="title">Figure 13. MicroPeak in Sunlight</div>
+</div>
+<div class="paragraph">
+<p>You can carefully cutting a piece of adhesive-backed open-cell foam
+and attach it to MicroPeak. It’s important to press the adhesive to
+the circuit board and not to the top of the barometric sensor or the
+sensor may become blocked and not operate at all. Once you’ve attached
+the foam, you should test MicroPeak on the ground to make sure it’s
+still working.</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-foam.jpg" alt="micropeak foam" width="430">
+</div>
+<div class="title">Figure 14. MicroPeak with Foam</div>
+</div>
+<div class="paragraph">
+<p>That MicroPeak was in the same barometric chamber as the one which
+generated the above results and the resulting flight data looks
+correct:</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-flight-foam.png" alt="micropeak flight foam" width="430">
+</div>
+<div class="title">Figure 15. MicroPeak in Sunlight with Foam</div>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_handling_precautions">Appendix A: Handling Precautions</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<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 devices, there are some precautions you
+must take.</p>
+</div>
+<div class="admonitionblock warning">
+<table>
+<tr>
+<td class="icon">
+<div class="title">Warning</div>
+</td>
+<td class="content">
+The CR1025 Lithium batteries have an extraordinary power
+density. This is great because we can fly with much less
+battery mass…​ but if they are punctured or their contacts
+are allowed to short, they can and will release their energy
+very rapidly! Thus we recommend that you take some care when
+handling MicroPeak to keep conductive material from coming in
+contact with the exposed metal elements.
+</td>
+</tr>
+</table>
+</div>
+<div class="paragraph">
+<p>The barometric sensor used in MicroPeak is sensitive to
+sunlight. Please consider this when designing an
+installation. Many model rockets with payload bays use clear
+plastic for the payload bay. Replacing these with an opaque
+cardboard tube, painting them, or wrapping them with a layer
+of masking tape are all reasonable approaches to keep the
+sensor out of direct sunlight.</p>
+</div>
+<div class="paragraph">
+<p>The barometric sensor sampling ports must be able to
+"breathe", both by not being covered by solid foam or tape or
+other materials that might directly block the hole on the top
+of the sensor, and also by having a suitable static vent to
+outside air.</p>
+</div>
+<div class="paragraph">
+<p>One good solution is to use a small rectangle of Poron
+50-30031-12X12P or equivalent to cover the sensor. This is an
+open cell foam in 1/32" thickness with an adhesive backing. It
+seems to do a good job of blocking sun while still allowing
+airflow to and from the sensor internals.</p>
+</div>
+<div class="paragraph">
+<p>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>
+</div>
+<div class="sect1">
+<h2 id="_technical_information">Appendix B: Technical Information</h2>
+<div class="sectionbody">
+<div class="sect2">
+<h3 id="_barometric_sensor">B.1. Barometric Sensor</h3>
+<div class="paragraph">
+<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.</p>
+</div>
+<div class="paragraph">
+<p>The pressure range corresponds roughly to an altitude
+range of -1500m (-4900 feet) to 31000m (102000 feet),
+while the resolution is approximately 20cm (8 inches)
+near sea level and 60cm (24in) at 10000m (33000 feet).</p>
+</div>
+<div class="paragraph">
+<p>Ground pressure is computed from an average of 16
+samples, 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>
+<div class="sect2">
+<h3 id="_micro_controller">B.2. Micro-controller</h3>
+<div class="paragraph">
+<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 storage of
+previous flight data.</p>
+</div>
+<div class="paragraph">
+<p>The ATtiny85 has a low-power mode which turns off all
+of the clocks and powers down most of the internal
+components. In 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>
+<div class="sect2">
+<h3 id="_lithium_battery">B.3. Lithium Battery</h3>
+<div class="paragraph">
+<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 sitting on the launch pad or
+during flight.</p>
+</div>
+<div class="paragraph">
+<p>The large positive terminal (+) is usually marked,
+while the smaller negative terminal is not. Make sure
+you install the battery with the positive terminal
+facing away from the circuit board where it will be in
+contact with the metal battery holder. A small pad on
+the circuit board makes contact with the negative
+battery terminal.</p>
+</div>
+<div class="paragraph">
+<p>Shipping restrictions may prevent us from including a
+CR1025 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>
+<div class="sect2">
+<h3 id="_atmospheric_model">B.4. Atmospheric Model</h3>
+<div class="paragraph">
+<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 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>
+</div>
+<div class="paragraph">
+<p>The model assumes a particular set of atmospheric
+conditions, 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="paragraph">
+<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>
+<div class="sect2">
+<h3 id="_mechanical_considerations">B.5. Mechanical Considerations</h3>
+<div class="paragraph">
+<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 ruggedness.</p>
+</div>
+<div class="paragraph">
+<p>The MicroPeak battery holder is designed to withstand
+impact up to 150g without breaking contact (or, worse
+yet, causing the battery to fall out). That means it
+should stand up to almost any launch you care to try,
+and should withstand fairly rough landings.</p>
+</div>
+<div class="paragraph">
+<p>The power switch is designed to withstand up to 50g
+forces in 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>
+<div class="sect2">
+<h3 id="_micropeak_programming_interface">B.6. MicroPeak Programming Interface</h3>
+<div class="paragraph">
+<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 × 0.85mm pads on 1.20mm centers exposed
+near the edge of the circuit board. We couldn’t find
+any connector that was small enough to include on the
+circuit board.</p>
+</div>
+<div class="paragraph">
+<p>In lieu of an actual connector, the easiest way to
+connect to the bare pads is through a set of Pogo
+pins. These spring-loaded contacts are designed to
+connect in precisely this way. We’ve designed a
+programming jig, the MicroPeak Pogo Pin board which
+provides a standard AVR interface on one end and a
+recessed slot for MicroPeak to align the board with
+the Pogo Pins.</p>
+</div>
+<div class="paragraph">
+<p>The MicroPeak Pogo Pin board is not a complete AVR
+programmer, it is an interface board that provides a
+3.3V regulated power supply to run the MicroPeak via
+USB and a standard 6-pin AVR programming interface
+with the usual 2x3 grid of pins on 0.1" centers. This
+can be connected to any AVR programming dongle.</p>
+</div>
+<div class="paragraph">
+<p>The AVR programming interface cannot run faster than ¼
+of the AVR CPU clock frequency. Because MicroPeak runs
+at 250kHz to save power, you must configure your AVR
+programming system to clock the AVR programming
+interface at no faster than 62.5kHz, or a clock period
+of 32µS.</p>
+</div>
+</div>
+</div>
+</div>
+<div class="sect1">
+<h2 id="_on_board_data_storage">Appendix C: On-board data storage</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<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
+flight. Barometric measurements from the ground before launch
+and at apogee are stored, and used at power-on to compute the
+height of the last flight.</p>
+</div>
+<div class="paragraph">
+<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 is the
+information captured with the MicroPeak USB adapter. It can
+also be read from MicroPeak through any AVR programming tool.</p>
+</div>
+<table class="tableblock frame-all grid-all stretch">
+<caption class="title">Table 1. MicroPeak EEPROM Data Storage</caption>
+<colgroup>
+<col style="width: 20%;">
+<col style="width: 10%;">
+<col style="width: 70%;">
+</colgroup>
+<tbody>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Address</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Size (bytes)</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Description</p></td>
+</tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">0x000</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">4</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Average ground pressure (Pa)</p></td>
+</tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">0x004</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">4</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Minimum flight pressure (Pa)</p></td>
+</tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">0x008</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">2</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Number of in-flight samples</p></td>
+</tr>
+<tr>
+<td class="tableblock halign-left valign-top"><p class="tableblock">0x00a … 0x1fe</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">2</p></td>
+<td class="tableblock halign-left valign-top"><p class="tableblock">Instantaneous flight pressure (Pa) low 16 bits</p></td>
+</tr>
+</tbody>
+</table>
+<div class="paragraph">
+<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
+from the previous sample, assuming that pressure doesn’t
+change by more more than 32kPa in a single sample
+interval. Note that this pressure data is <strong>not</strong> filtered in
+any way, while both the recorded ground and apogee pressure
+values are, so you shouldn’t expect the minimum instantaneous
+pressure value to match the recorded minimum pressure value
+exactly.</p>
+</div>
+<div class="paragraph">
+<p>MicroPeak samples pressure every 96ms, but stores only every
+other sample in the EEPROM. This provides for 251 pressure
+samples at 192ms intervals, or 48.192s of storage. The clock
+used for these samples is a factory calibrated RC circuit
+built into the ATtiny85 and is accurate only to within ±10% at
+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>
+</div>
+</div>
+<div id="footer">
+<div id="footer-text">
+Version v1.9.2<br>
+Last updated 2020-02-26 00:13:45 -0700
+</div>
+</div>
+</body>
+</html>
\ No newline at end of file
projects / web / altusmetrum / blobdiff