EasyMega

This is a high-end recording dual-deploy altimeter for high power model rocketry. The feature set is identical to TeleMega, but without the integrated GPS and telemetry link. This makes EasyMega an ideal choice for complex projects including sustainers on multi-stage projects where integrated radio functionality isn't needed. 4 of the 6 pyro events are configurable and can be based on time and various flight events and status, including angle from vertical.

For the latest EasyMega firmware and related ground station software, please visit the AltOS page on this site. EasyMega requires AltOS version 1.4.2 or later.

Here are photos of version 1.0 (we may get around to taking picutres of 2.0 eventually, but it looks substantially similar):

Features

User View

• Recording altimeter for high power model rocketry
• Supports dual deployment and 4 additional pyro events.
  Pyro events are configurable and can be based on time and various flight events and status, including angle from vertical (for safety in staging and air start flights).
• Barometric pressure sensor good to 100k feet MSL
• 3-axis 200-g accelerometer for motor characterization
• 3-axis 16-g accelerometer for gyro calibration
• 3-axis 2000 deg/sec gyros
• 3-axis magnetic sensor
• On-board non-volatile memory for flight data storage
• Can drive up to 4 RC-style servos
• USB for power, configuration, and data recovery
• Integrated support for LiPo rechargeable batteries
• User choice of pyro battery configuration, can use primary LiPo or any customer-chosen separate pyro battery up to 12 volts nominal.
• 2.25 x 1.25 inch board designed to fit inside 38mm airframe coupler tube

Developer View

• Hardware Features
  • ST Micros STM32L151 ARM Cortex M3 based Microcontroller
  • 150mA 3.3V LDO regulator
  • Winbond W25Q64CV serial flash memory
  • Measurement Specialties MS5607 Micro Altimeter Module
    • Wide range — 120kPa to 1kPa (approximately -1500m to 31000m)
    • High precision — 2.4Pa resolution (approximately 20cm at sea level)
    • Factory calibrated.
  • Analog Devices ADXL375 3-Axis Digital MEMS Accelerometer

          * +- 200g full-scale
          * on-chip digitizer
    

  • Invensense MPU-9250 Nine-Axis MEMS Motion Tracking Device
    • tri-axis angular rate sensor up to 2000 degrees/second
    • tri-axis accelerometer with +- 16g range
    • tri-axis magnetic (compass) sensor
    • three on-chip ADCs for true simultaneous sampling of all axes
• 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
  • Lepton EDA for schematic capture and pcb-rnd for PCB layout
• Licenses
  • The hardware is licensed under the TAPR Open Hardware License
  • The software is licensed GPL version 2

Artifacts

There is a single manual for EasyMega and most other Altus Metrum products, which is available in html and pdf formats.

An outline of the board with drill hole locations is available in pdf format.

The hardware design current gEDA files are available from git.gag.com in the project hw/easymega.

For those who don't have ready access to the gEDA suite, here are pdf snapshots of the files for Production PCB version 5.0 in more easily readable form:

• schematic
• pcb artwork
• bill of materials

History of EasyMega

Status

Version 2.0 production units are now available for sale.