= MicroPeak Owner's Manual
+Keith Packard <keithp@keithp.com>; Bdale Garbee <bdale@gag.com>
+:revnumber: v1.9
+:revdate: 8 Oct 2018
+:copyright: Bdale Garbee and Keith Packard 2018
+:stylesheet: am.css
+:linkcss:
+:toc:
:doctype: book
:numbered:
+:pdf-stylesdir: .
+:pdf-style: altusmetrum
+:pdf-fontsdir: fonts
+
+ include::header.adoc[]
[dedication]
== Acknowledgements
MicroPeak is designed to be easy to use. Requiring no external
components, flying takes just a few steps
- * 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.
+ 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.
.MicroPeak and Battery
- image::micropeak-back.jpg[width="4.5in"]
-
- * 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.
-
- * 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.
-
- * Finish preparing the rocket for flight. 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.
-
- * Fly the rocket. 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.
-
- * 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.
+ image::micropeak-back.jpg[width=430]
+
+ 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.
+
+ 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.
+
+ Finish preparing the rocket for flight::
+
+ 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.
+
+ Fly the rocket::
+
+ 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.
+
+ 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.
== The MicroPeak USB adapter
.MicroPeak USB Adapter
- image::MicroPeakUSB-2.0.jpg[width="4.5in"]
+ image::MicroPeakUSB-2.0.jpg[width=430,align="center"]
MicroPeak stores barometric pressure information for the first
48 seconds of the flight in on-board non-volatile memory. The
* Start the MicroPeak application.
- image::micropeak-nofont.svg[width="0.5in"]
+ image::micropeak-nofont.svg[width=50,align="center"]
* Click on the Download button at the top of the
window.
.MicroPeak Application
- image::micropeak-app.png[width="4.5in"]
+ image::micropeak-app.png[width=430,align="center"]
* Select from the listed devices. There will probably
be only one.
.MicroPeak Device Dialog
- image::micropeak-device-dialog.png[width="2.3in"]
+ image::micropeak-device-dialog.png[width=220,align="center"]
* The application will now wait until it receives
valid data from the MicroPeak USB adapter.
.MicroPeak Download Dialog
- image::micropeak-download.png[width="2in"]
+ image::micropeak-download.png[width=200,align="center"]
* The MicroPeak USB adapter has a small
phototransistor under the hole in the center of the
MicroPeak board itself.
.MicroPeak Downloading
- image::MicroPeakUSB-2.0-inuse.jpg[width="4.5in"]
+ image::MicroPeakUSB-2.0-inuse.jpg[width=430,align="center"]
* After the maximum flight height is reported,
MicroPeak will pause for a few seconds, blink the
MicroPeak board and try again.
.MicroPeak Save Dialog
- image::micropeak-save-dialog.png[width="2.3in"]
+ image::micropeak-save-dialog.png[width=220,align="center"]
* Once the data are saved, a graph will be displayed
with height, speed and acceleration values computed
- from the recorded barometric pressure data. See the
- next section for more details on that.
+ from the recorded barometric pressure data. See
+ <<_analyzing_micropeak_data> for more details on that.
=== Analyzing MicroPeak Data
==== MicroPeak Graphs
.MicroPeak Graph
- image::micropeak-graph.png[width="4.5in"]
+ image::micropeak-graph.png[width=430,align="center"]
Under the Graph tab, the height, speed and acceleration values
are displayed together. You can zoom in on the graph by
==== MicroPeak Flight Statistics
.MicroPeak Flight Statistics
- image::micropeak-statistics.png[width="4.5in"]
+ image::micropeak-statistics.png[width=430,align="center"]
The Statistics tab presents overall data from
the flight. Note that the Maximum height value
==== Raw Flight Data
.MicroPeak Raw Flight Data
- image::micropeak-raw-data.png[width="4.5in"]
+ image::micropeak-raw-data.png[width=430,align="center"]
A table consisting of the both the raw barometric pressure
data and values computed from that for each recorded time.
==== Configuring the Graph
.MicroPeak Graph Configuration
- image::micropeak-graph-configure.png[width="4.5in"]
+ image::micropeak-graph-configure.png[width=430,align="center"]
This selects which graph elements to show, and lets you
switch between metric and imperial units
=== Setting MicroPeak Preferences
.MicroPeak Preferences
- image::micropeak-preferences.png[width="1.8in"]
+ image::micropeak-preferences.png[width=170,align="center"]
The MicroPeak application has a few user settings which are
configured through the Preferences dialog, which can be
these applications, change in one application
will affect the other.
+== Protecting MicroPeak from Sunlight
+
+ 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 as much as 3000-4000
+ feet.
+
+ 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.
+
+ 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:
+
+ .MicroPeak in Sunlight
+ image::micropeak-flight-nofoam.png[width=430]
+
+ 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.
+
+ .MicroPeak with Foam
+ image::micropeak-foam.jpg[width=430]
+
+ That MicroPeak was in the same barometric chamber as the one which
+ generated the above results and the resulting flight data looks
+ correct:
+
+ .MicroPeak in Sunlight with Foam
+ image::micropeak-flight-foam.png[width=430]
+
[appendix]
== Handling Precautions
sensor out of direct sunlight.
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.
+ "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.
+
+ 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.
As with all other rocketry electronics, Altus Metrum
altimeters must be protected from exposure to corrosive motor
projects / fw / altos / blobdiff