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.


The MicroPeak manual is available in html and pdf formats.


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 1.3.2 is a minor release. It includes small bug fixes for the TeleMega flight software and AltosUI ground station

AltOS Firmware Changes

  • On TeleMega, limit number of logged GPS status information to 12 satellites. That's all there is room for in the log structure.

  • Improve APRS behavior. Remembers last known GPS position and keeps sending that if we lose GPS lock. Marks locked/unlocked by sending L/U in the APRS comment field along with the number of sats in view and voltages.

AltosUI changes

  • If the TeleMega flight firmware reports that it has logged information about more than 12 satellites, don't believe it as the log only holds 12 satellite records.

  • Track the maximum height as computed from GPS altitude data and report that in the flight summary data.

  • Use letters (A, B, C, D) for alternate pyro channel names instead of numbers (0, 1, 2, 3) in the Fire Igniter dialog.

Version 1.3.1 is a minor release. It improves support for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini.

AltOS Firmware Changes

  • Improve sensor boot code. If sensors fail to self-test, the device will still boot up and check for pad/idle modes. If in idle mode, the device will warn the user with a distinct beep, if in Pad mode, the unit will operate as best it can. Also, the Z-axis accelerometer now uses the factory calibration values instead of re-calibrating on the pad each time. This avoids accidental boost detect when moving the device around while in Pad mode.

  • Fix antenna-down mode accelerometer configuration. Antenna down mode wasn't working because the accelerometer calibration values were getting re-computed incorrectly in inverted mode.

  • Improved APRS mode. Now uses compressed position format for smaller data size, improved precision and to include altitude data as well as latitude and longitude. Also added battery and pyro voltage reports in the APRS comment field so you can confirm that the unit is ready for launch.

AltosUI changes

  • Display additional TeleMega sensor values in real units. Make all of these values available for plotting. Display TeleMega orientation value in the Ascent and Table tabs.

  • Support additional TeleMega pyro channels in the Fire Igniter dialog. This lets you do remote testing of all of the channels, rather than just Apogee and Main.

  • Limit data rate when downloading satellite images from Google to make sure we stay within their limits so that all of the map tiles download successfully.

Version 1.3 is a major release. It adds support for TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini.

AltOS Firmware Changes

  • Add STM32L processor support. This includes enhancements to the scheduler to support products with many threads.

  • Add NXP LPC11U14 processor support.

  • Support additional pyro channels. These are configurable through the UI to handle air starts, staging, additional recovery events and external devices such as cameras.

  • Add 3-axis gyro support for orientation tracking. This integrates the gyros to compute the angle from vertical during flight, allowing the additional pyro events to be controlled by this value.

  • Many more device drivers, including u-Blox Max 7Q GPS, Freescale MMA6555 digital single-axis accelerometer, Invensense MPU6000 3-axis accelerometer + 3 axis gyro, Honeywell HMC5883 3-axis magnetic sensor and the TI CC1120 and CC115L digital FM transceivers

AltosUI changes

  • Support TeleMega, TeleMetrum v2.0, TeleMini v2.0 and EasyMini telemetry and log formats.

  • Use preferred units for main deployment height configuration, instead of always doing configuration in meters.

MicroPeak UI changes

  • Add 'Download' button to menu bar.

  • Save the last log directory and offer that as the default for new downloads

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