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diff --git a/doc/micropeak.xsl b/doc/micropeak.xsl new file mode 100644 index 00000000..96179d01 --- /dev/null +++ b/doc/micropeak.xsl @@ -0,0 +1,581 @@ +<?xml version="1.0" encoding="utf-8" ?> +<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" + "/usr/share/xml/docbook/schema/dtd/4.5/docbookx.dtd"> +<book> + <title>MicroPeak Owner's Manual</title> + <subtitle>A recording altimeter for hobby rocketry</subtitle> + <bookinfo> + <author> + <firstname>Keith</firstname> + <surname>Packard</surname> + </author> + <copyright> + <year>2012</year> + <holder>Bdale Garbee and Keith Packard</holder> + </copyright> + <legalnotice> + <para> + This document is released under the terms of the + <ulink url="http://creativecommons.org/licenses/by-sa/3.0/"> + Creative Commons ShareAlike 3.0 + </ulink> + license. + </para> + </legalnotice> + <revhistory> + <revision> + <revnumber>0.1</revnumber> + <date>29 October 2012</date> + <revremark> + Initial release with preliminary hardware. + </revremark> + </revision> + <revision> + <revnumber>1.0</revnumber> + <date>18 November 2012</date> + <revremark> + Updates for version 1.0 release. + </revremark> + </revision> + <revision> + <revnumber>1.1</revnumber> + <date>12 December 2012</date> + <revremark> + Add comments about EEPROM storage format and programming jig. + </revremark> + </revision> + <revision> + <revnumber>1.2</revnumber> + <date>20 January 2013</date> + <revremark> + Add documentation for the MicroPeak USB adapter board. Note + the switch to a Kalman filter for peak altitude + determination. + </revremark> + </revision> + </revhistory> + </bookinfo> + <acknowledgements> + <para> + Thanks to John Lyngdal for suggesting that we build something like this. + </para> + <para> + Have fun using these products, and we hope to meet all of you + out on the rocket flight line somewhere. + <literallayout> +Bdale Garbee, KB0G +NAR #87103, TRA #12201 + +Keith Packard, KD7SQG +NAR #88757, TRA #12200 + </literallayout> + </para> + </acknowledgements> + <chapter> + <title>Quick Start Guide</title> + <para> + MicroPeak is designed to be easy to use. Requiring no external + components, flying takes just a few steps + </para> + <itemizedlist> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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, and shield it from light as that can + cause incorrect sensor readings. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + </itemizedlist> + </chapter> + <chapter> + <title>Handling Precautions</title> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + As with all other rocketry electronics, Altus Metrum altimeters must + be protected from exposure to corrosive motor exhaust and ejection + charge gasses. + </para> + </chapter> + <chapter> + <title>The MicroPeak USB adapter</title> + <para> + 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. + </para> + <section> + <title>Installing the MicroPeak software</title> + <para> + The MicroPeak application runs on Linux, Mac OS X and + Windows. You can download the latest version from + <ulink url="http://altusmetrum.org/AltOS"/>. + </para> + <para> + 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 <ulink + url="http://www.ftdichip.com/FTDrivers.htm"/>. + </para> + </section> + <section> + <title>Downloading Micro Peak data</title> + <itemizedlist> + <listitem> + <para> + Connect the MicroPeak USB adapter to a USB cable and plug it + in to your computer. + </para> + </listitem> + <listitem> + <para> + Start the MicroPeak application, locate the File menu and + select the Download entry. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + </itemizedlist> + </section> + <section> + <title>Analyzing MicroPeak Data</title> + <para> + The MicroPeak application can present flight data in the form + of a graph, a collection of computed statistics or in tabular + form. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + A table consisting of the both the raw barometric pressure + data and values computed from that for each recorded time. + </para> + <para> + 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. + </para> + </section> + <section> + <title>Configuring the MicroPeak application</title> + <para> + The MicroPeak application has a few user settings which are + configured through the Preferences dialog, which can be + accessed from the File menu. + <itemizedlist> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + <listitem> + <para> + 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. + </para> + </listitem> + </itemizedlist> + </para> + <para> + 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. + </para> + </section> + </chapter> + <chapter> + <title>Technical Information</title> + <section> + <title>Barometric Sensor</title> + <para> + 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. + </para> + <para> + 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). + </para> + <para> + 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. + </para> + </section> + <section> + <title>Micro-controller</title> + <para> + 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. + </para> + <para> + 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. + </para> + </section> + <section> + <title>Lithium Battery</title> + <para> + The CR1025 battery used by MicroPeak holes 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + </section> + <section> + <title>Atmospheric Model</title> + <para> + 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. + </para> + <para> + 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. + </para> + </section> + <section> + <title>Mechanical Considerations</title> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + </section> + <section> + <title>On-board data storage</title> + <para> + 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. + </para> + <para> + 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 + tool. + </para> + <table frame='all'> + <title>MicroPeak EEPROM Data Storage</title> + <tgroup cols='3' align='center' colsep='1' rowsep='1'> + <colspec align='center' colwidth='2*' colname='Address'/> + <colspec align='center' colwidth='*' colname='Size (bytes)'/> + <colspec align='left' colwidth='7*' colname='Description'/> + <thead> + <row> + <entry align='center'>Address</entry> + <entry align='center'>Size (bytes)</entry> + <entry align='center'>Description</entry> + </row> + </thead> + <tbody> + <row> + <entry>0x000</entry> + <entry>4</entry> + <entry>Average ground pressure (Pa)</entry> + </row> + <row> + <entry>0x004</entry> + <entry>4</entry> + <entry>Minimum flight pressure (Pa)</entry> + </row> + <row> + <entry>0x008</entry> + <entry>2</entry> + <entry>Number of in-flight samples</entry> + </row> + <row> + <entry>0x00a … 0x1fe</entry> + <entry>2</entry> + <entry>Instantaneous flight pressure (Pa) low 16 bits</entry> + </row> + </tbody> + </tgroup> + </table> + <para> + 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 <emphasis>not</emphasis> + 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. + </para> + <para> + 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. + </para> + </section> + <section> + <title>MicroPeak Programming Interface</title> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + <para> + 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. + </para> + </section> + </chapter> +</book> +<!-- LocalWords: Altusmetrum MicroPeak +--> |