X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=blobdiff_plain;f=doc%2Fmicropeak.xsl;h=dafe36820650fa73f87da3691e7af758d74d2621;hp=284d0fb04a359ff11e7b3f865d9dee5b7f841f78;hb=HEAD;hpb=ceea0e75ac42acac4a20bf88f34bb93fd2768f4c diff --git a/doc/micropeak.xsl b/doc/micropeak.xsl deleted file mode 100644 index 284d0fb0..00000000 --- a/doc/micropeak.xsl +++ /dev/null @@ -1,278 +0,0 @@ - - - - MicroPeak Owner's Manual - A peak-recording altimeter for hobby rocketry - - - Keith - Packard - - - 2012 - Bdale Garbee and Keith Packard - - - - This document is released under the terms of the - - Creative Commons ShareAlike 3.0 - - license. - - - - - 0.1 - 29 October 2012 - - Initial release with preliminary hardware. - - - - 1.0 - 18 November 2012 - - Updates for version 1.0 release. - - - - - - - Thanks to John Lyngdal for suggesting that we build something like this. - - - Have fun using these products, and we hope to meet all of you - out on the rocket flight line somewhere. - -Bdale Garbee, KB0G -NAR #87103, TRA #12201 - -Keith Packard, KD7SQG -NAR #88757, TRA #12200 - - - - - Quick Start Guide - - 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 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 - 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. - - - - - 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. - - - - - 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. - - - - - - Handling Precautions - - 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. - - - 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. - - - 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. - - - 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. - - - As with all other rocketry electronics, Altus Metrum altimeters must - be protected from exposure to corrosive motor exhaust and ejection - charge gasses. - - - - Technical Information -
- Barometric Sensor - - 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. - - - 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). - - - 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. - -
-
- Micro-controller - - 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. - - - 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. - -
-
- Lithium Battery - - 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. - - - 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. - - - 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. - -
-
- Atmospheric Model - - 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. - - - 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. - -
-
- Mechanical Considerations - - 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. - - - 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. - - - 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. - -
- - -