X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=doc%2Fmicropeak.txt;h=f1feeec41423a557948c19d4e9c14c9bf451bb82;hp=d5036a00674708648e459d98a5540972e4c3195d;hb=0a466e9869633c6ce7e43ff24ba2afff938461dd;hpb=87cb41dfa07153b4dc44f723c65888945b3a11b1 diff --git a/doc/micropeak.txt b/doc/micropeak.txt index d5036a00..f1feeec4 100644 --- a/doc/micropeak.txt +++ b/doc/micropeak.txt @@ -1,6 +1,18 @@ = MicroPeak Owner's Manual +Keith Packard ; Bdale Garbee +: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 @@ -32,7 +44,7 @@ positive (+) terminal facing away from the circuit board. .MicroPeak and Battery - image::micropeak-back.jpg[width="4.5in"] + image::micropeak-back.jpg[width=430] Install MicroPeak in your rocket:: @@ -87,7 +99,7 @@ == The MicroPeak USB adapter .MicroPeak USB Adapter - image::MicroPeakUSB-2.0.jpg[width="4.5in",align="center"] + 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 @@ -112,25 +124,25 @@ * Start the MicroPeak application. - image::micropeak-nofont.svg[width="0.5in",align="center"] + 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",align="center"] + 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",align="center"] + 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",align="center"] + image::micropeak-download.png[width=200,align="center"] * The MicroPeak USB adapter has a small phototransistor under the hole in the center of the @@ -142,7 +154,7 @@ MicroPeak board itself. .MicroPeak Downloading - image::MicroPeakUSB-2.0-inuse.jpg[width="4.5in",align="center"] + 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 @@ -154,7 +166,7 @@ MicroPeak board and try again. .MicroPeak Save Dialog - image::micropeak-save-dialog.png[width="2.3in",align="center"] + 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 @@ -194,7 +206,7 @@ ==== MicroPeak Graphs .MicroPeak Graph - image::micropeak-graph.png[width="4.5in",align="center"] + 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 @@ -205,7 +217,7 @@ ==== MicroPeak Flight Statistics .MicroPeak Flight Statistics - image::micropeak-statistics.png[width="4.5in",align="center"] + image::micropeak-statistics.png[width=430,align="center"] The Statistics tab presents overall data from the flight. Note that the Maximum height value @@ -220,7 +232,7 @@ ==== Raw Flight Data .MicroPeak Raw Flight Data - image::micropeak-raw-data.png[width="4.5in",align="center"] + 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. @@ -228,7 +240,7 @@ ==== Configuring the Graph .MicroPeak Graph Configuration - image::micropeak-graph-configure.png[width="4.5in",align="center"] + 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 @@ -236,7 +248,7 @@ === Setting MicroPeak Preferences .MicroPeak Preferences - image::micropeak-preferences.png[width="1.8in",align="center"] + 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 @@ -287,6 +299,43 @@ 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 @@ -315,10 +364,16 @@ 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