Altus Metrum/ MicroPeak

Introducing MicroPeak by AltusMetrum

Micropeak is a barometric logging altimeter for precision model rocketry altitude measurements.

Production units are available from the Garbee and Garbee web store and Apogee Components

Data download is available using the MicroPeak USB adapter.

Documentation

The MicroPeak manual is available in html and pdf formats.

Software

The MicroPeak application runs on Linux, Mac OS X and Windows. It communicates with the MicroPeak USB adapter to download and analyze flight data. It's written in Java and offers the same functionality and interface on all three platforms. It uses the FTDI USB Serial drivers to communicate with the hardware. If you're running Mac OS X or Windows, a compatible version of those drivers is included with the software. You can also install a different from from the FTDI Driver page.

Available Versions

Version 1.2.1 is a minor release. It adds support for TeleBT and the AltosDroid application, provides several new features in AltosUI and fixes some bugs in the AltOS firmware.

AltOS Firmware Changes

  • Add support for TeleBT
  • In TeleMini recovery mode (when booted with the outer two debug pins connected together), the radio parameters are also set back to defaults (434.550MHz, N0CALL, factory radio cal).
  • Add support for reflashing the SkyTraq GPS chips. This requires special host-side code which currently only exists for Linux.
  • Correct Kalman filter model error covariance matrix. The values used previously assumed continuous measurements instead of discrete measurements.
  • Fix some bugs in the USB driver for TeleMetrum and TeleDongle that affected Windows users.
  • Adjusted the automatic gain control parameters that affect receive performance for TeleDongle. Field tests indicate that this may improve receive performance somewhat.

AltosUI Changes

  • Handle missing GPS lock in 'Descent' tab. Previously, if the GPS position of the pad was unknown, an exception would be raised, breaking the Descent tab contents.
  • Improve the graph, adding tool-tips to show values near the cursor and making the displayed set of values configurable, adding all of the flight data as options while leaving the default settings alone so that the graph starts by showing height, speed and acceleration.
  • Make the initial position of the AltosUI top level window configurable. Along with this change, the other windows will pop up at 'sensible' places now, instead of on top of one another.
  • Add callsign to Monitor idle window and connecting dialogs. This makes it clear which callsign is being used so that the operator will be aware that it must match the flight computer value or no communication will work.
  • When downloading flight data, display the block number so that the user has some sense of progress. Unfortunately, we don't know how many blocks will need to be downloaded, but at least it isn't just sitting there doing nothing for a long time.
  • Add GPS data and a map to the graph window. This lets you see a complete summary of the flight without needing to 'replay' the whole thing.

Version 1.2 represents first release of software supporting MicroPeak.

Hardware Features

  • Measure ground pressure and peak altitude pressure.
  • Logs 48 seconds of flight data
  • Orange LED blinks out maximum height in decimeters.
  • 18mm x 14mm. 1.9g including battery.
  • Power switch.

The CR1025 battery holder is mounted on the back side of the board, so there are no external wires or batteries to manage.

Software features

  • Saves last flight data to non-volatile memory.
  • Reports previous flight on power-on.
  • Automatically shuts down on landing to preserve battery.

Battery Holder

MicroPeak includes an integrated battery holder on the back side of the circuit board.

Developer View

Here's a close-up view of the hardware

  • Hardware Features

    • ATMEL ATtiny85 Microcontroller
      • 8K flash
      • 512B RAM
      • 512B EEPROM
      • SPI/I2C interface
    • 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.
    • CR1025 Lithium Battery
      • 30mAh. Runs MicroPeak for more than 40 hours on the pad or in flight
    • OSRAM LO T67K orange LED
    • Standard 6-pin AVR programming interface.

  • Software Features

    • Written in C
    • Samples pressure every 96ms
    • Delay 30s after power-on to finish airframe prep
    • Detect boost with 10m altitude change
    • Exponential averaging filter to minimize transient effects.

  • Tools Used

    • gEDA for schematic capture and PCB layout
    • GCC as an AVR cross-compiler

  • Licenses