# MegaMetrum

This is a high-end recording dual-deploy altimeter for high power model 
rocketry with integrated GPS and telemetry link.  The features included
make MegaMetrum the ideal choice for complex projects including sustainers
on multi-stage projects.

For the latest MegaMetrum firmware and related ground station software, please
visit the [AltOS](../AltOS) page on this site.

These are no photos of MegaMetrum to share yet.

## Features ##

### User View ###

* Recording altimeter for high power model rocketry
* Supports dual deployment and additional pyro events (can fire 6 charges)
* 70cm ham-band transceiver for telemetry downlink
* Barometric pressure sensor good to 100k feet MSL
* 1-axis 105-g accelerometer for motor characterization
* 3-axis 18-g accelerometer for gyro calibration
* 3-axis 2000 deg/sec gyros
* 3-axis magnetic sensor
* On-board, integrated GPS receiver
* On-board non-volatile memory for flight data storage
* USB for power, configuration, and data recovery
* Integrated support for LiPo rechargeable batteries
* Uses LiPo to fire e-matches, can be factory modified to support separate pyro battery
* 3.25 x 1.25 inch board designed to fit inside 38mm airframe coupler tube

### Developer View ###

* Hardware Features
	* ST Micros [STM32L151](http://www.st.com/internet/mcu/product/248821.jsp) ARM Cortex M3 based Microcontroller
	* TI [CC1120](http://www.ti.com/product/cc1120) High Performance RF Transceiver for Narrowband Systems 
	* 150mA 3.3V LDO regulator
		* takes input from USB interface by default
		* output appears on 8-pin companion connector
		* can take input from 8-pin companion connector in non-USB applications
	* [Winbond W25Q64CV](http://www.winbond.com/hq/enu/ProductAndSales/ProductLines/FlashMemory/SerialFlash/W25Q64CV.htm) serial flash memory
	* [SkyTraq](http://www.skytraq.com.tw/) Venus634FLPx GPS receiver
		* on-board [Taoglas AP.17A.01](http://www.taoglas.com/antennas/GPS_Antennas/Internal_GPS_-_Active_Patch_Modules/) 
		  single-stage active patch antenna
		* U.FL connector with 3.3V DC can be re-purposed for optional external amplified antennas
		* async serial interface
	* Measurement Specialties [MS5607](http://www.meas-spec.com/product/t_product.aspx?id=8499) Micro Altimeter Module
		* Wide range — 120kPa to 1kPa (approximately -1500m to 31000m)
		* High precision — 2.4Pa resolution (approximately 20cm at sea level)
		* Factory calibrated.
	* Freescale [MMA655x](http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MMA65xx&fsrch=1&sr=1) Single Axis SPI Intertial Sensor
		* +- 105g or 120g full-scale
		* on-chip 12-bit digitizer
	* Invensense [MPU-6000](http://invensense.com/mems/gyro/mpu6050.html) Six-Axis MEMS Motion Tracking Device
		* tri-axis angular rate sensor up to 2000 degrees/second
		* tri-axis accelerometer with +- 16g range
		* three on-chip ADCs for true simultaneous sampling of all axes
	* Honeywell [HMC5883L](http://www.magneticsensors.com/three-axis-digital-compass.php) 3-Axis Digital Compass IC
* Software Features
	* Written mostly in C with some ARM assembler
	* Runs from on-chip flash, uses on-chip RAM, stores flight data to serial flash
	* USB serial emulation for "console" interface
* Tools Used
	* [gEDA](http://www.gpleda.org/) for schematic capture and PCB layout
* Licenses
	* The hardware is licensed under the [TAPR](http://www.tapr.org) [Open Hardware License](http://www.tapr.org/ohl.html)
	* The software is licensed [GPL version 2](http://www.gnu.org/licenses/old-licenses/gpl-2.0.html)

## Artifacts ##

There is a single manual for MegaMetrum and most other Altus Metrum products,
which is available in [html](../AltOS/doc/altusmetrum.html) and 
[pdf](../AltOS/doc/altusmetrum.pdf) formats.

The hardware design current gEDA files are available from 
[git.gag.com](http://git.gag.com) in the project 
[hw/megametrum](http://git.gag.com/?p=hw/megametrum;a=summary).  

## Future Plans ##

MegaMetrum v0.1 prototypes are working and flight testing is underway.

There will be at least one more prototype version to try out a different
GPS receiver and improve various design details... most likely at least
2 more prototype versions before we go to production.

No firm schedule for production and sale of MegaMetrum has been set yet, 
but we hope to offer this product in time for the 2013 flying season.