GoBalloon

For a quick introduction to GoBalloon, have a look at the presentation I gave to the Seattle Go Developers Meetup.

GoBalloon is a High Altitude Balloon payload controller in Go. The software is designed to run on a BeagleBone Black single board computer, which provides a full Linux environment while still being lightweight enough to fly in a balloon.

GoBalloon communicates back to earth via amateur radio and the APRS protocol; the software includes a layer 2 protocol (AX.25) implementation that is used to drive a radio modem called a Terminal Node Controller (TNC). Using the TNC, GoBalloon periodically reports its position and altitude and listens for commands from the ground. When flying, GoBalloon uses a locally-attached TNC via serial port. For debugging on the ground, GoBalloon also supports a network-attached TNC via my tnc-server software.

GoBalloon is capable of bi-directional communication with the ground and includes an APRS library that encodes and decodes most of the popular APRS packet formats including position reports (compressed and uncompressed), messages (send/receive/ACK), and telemetry (compressed and uncompressed).

GoBalloon includes GPIO support and will trigger an external cut-down device when a cut-down message is received via APRS messaging. GPIO is also used to activate a piezoelectric buzzer upon descent to aid searchers looking for the landed payload.

GoBalloon uses gpsd to communicate with its GPS receiver and thanks to gpsd, supports a wide range of GPS devices. When flying, the software uses a locally-attached GPS via serial port but supports a remote GPS via TCP when debugging on the ground.

What Works

• APRS Controller (sends position reports, receives+acks cutdown messages)
• Balloon cutdown, triggered remotely by APRS message
• Burst detection with activation of buzzer/strobe upon descent
• NMEA GPS processing / gpsd integration
• AX.25/KISS packet encoding and decoding over local serial line and TCP
• APRS packet parser-dispatcher: examines the raw packets and dispatches appropriate decoder(s)
• APRS position reports encoding and decoding (compressed and uncompressed, with and without timestamps)
• APRS telemetry reports encoding and decoding (compressed and uncompressed)
• APRS messaging
• Geospatial calculations - Great Circle distance/bearing
• APRS-IS client (ganked from @dustin)
• APRS-style Base91 encoding

In Progress

• PCB design for BeagleBone cape that integrates:
  • uBLOX MAX-7 from HAB Supplies
  • Texas Instruments INA219 I²C power monitoring chip
  • Dimension Engineering switching voltage regulator
• Text-based console for chase vehicles

Not Yet Complete

• Support for I²C TNC connection (requires some additions to @davecheney's i2c library)
• Input voltage detection and reporting
• Camera servo control
• HTTP console for use during pre-flight checks
• High altitude digipeater