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
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.
Add documentation for the MicroPeak USB adapter board. Note
the switch to a Kalman filter for peak altitude
determination.
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
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>
Keith Packard, KD7SQG<br>
NAR #88757, TRA #12200<br>
</p></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>
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.
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.
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
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.
As with all other rocketry electronics, Altus Metrum altimeters must
be protected from exposure to corrosive motor exhaust and ejection
charge gasses.
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.
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.
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>.
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>.
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>.
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.
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.
The MicroPeak application can present flight data in the form
of a graph, a collection of computed statistics or in tabular
form.
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.
Data tab) to a file, change the application Preferences, Close
the current window or close all windows and Exit the
application.
The MicroPeak application has a few user settings which are
configured through the Preferences dialog, which can be
accessed from the File menu.
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.
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.
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.
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.
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.
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
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.
this mode, the chip consumes only .1μA of power. MicroPeak
uses this mode once the flight has ended to preserve battery
power.
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
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.
battery with MicroPeak. If so, many stores carry CR1025
batteries as they are commonly used in small electronic
devices such as flash lights.
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
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.
altitude is subtracted from the computed apogee altitude, so
the resulting height is more accurate than either the ground
or apogee altitudes.
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
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.
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.
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
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.
at regular intervals during the flight. This information can
be extracted from MicroPeak through any AVR programming
tool.
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
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.
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.
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 ×
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 ×
projects / web / altusmetrum / blobdiff