Use this manual to read OnFlight recordings, receive live flight data, or send measurements from an external sensor to the Hub. Output means data sent by the Hub; input means data sent to it.
| Task | Interface | Reference |
|---|---|---|
| Read a flight recording | .onflight file on the microSD card |
Log file format |
| Receive live sensor and navigation data | Custom UDP messages over Wi-Fi | UDP output format |
| Send external sensor measurements to the Hub | Custom UDP messages over Wi-Fi | UDP input format |
| Receive position and attitude in a flight application | GDL 90 over Wi-Fi | GDL 90 output format |
Data logger
The Hub records sensor measurements and navigation estimates to .onflight files on a microSD card. Use this interface to analyze recorded flights or add native OnFlight file support to an application. Recording does not require a Wi-Fi connection.
A log contains a sequence of binary packets. Each packet has a header identifying its type, a version identifying its layout, and a checksum for checking whether its bytes are intact. Some packets contain measurements; others describe the aircraft, pilot, or analog channels.
Hub Plus uses data version 3, including precise time fields and onboard analog inputs. The log chapter covers data versions 0–3 and the metadata packets, including how to locate them in the file. The separate .acrowrx format is not covered here.
See Log file format for the bytes in each packet and how to read them.
UDP output
Connect to the Hub’s Wi-Fi network to receive live measurements as broadcast UDP datagrams. Hub data is broadcast on port 2000 at 50 Hz. Separate output messages provide Stadia measurements, heart rate, and aircraft metadata on ports 2003–2005.
Hub message versions 0 and 1 include external measurements in the port 2000 packet; version 2 carries only Hub data. Select the decoder using the packet’s version byte.
See UDP output format for ports, rates, message layouts, and status flags.
UDP input
External devices can send measurements to the Hub by broadcasting UDP datagrams on its Wi-Fi network. Inputs include air data on port 2001, AGL altitude on port 2002, and four analog channels on ports 2006–2009. Send 1–50 messages per second for each input or analog channel.
See UDP input format for the field layouts, scaling, status flags, and firmware compatibility requirements.
GDL 90 output
The Hub sends position and attitude to compatible flight applications using GDL 90 over Wi-Fi, on a default port of 4000. This interface has its own framing and message definitions. See GDL 90 output format for transport, framing, and protocol references.
Version numbers
| Version | Meaning |
|---|---|
| Hub firmware version | Software release running on the device |
| Binary data version | Layout of a BF log frame |
| Metadata version | Layout of an MD or AD metadata packet; each has its own version |
| UDP message version | Layout of a datagram on a particular port |
Each interface has its own version numbers. For example, log data version 2 and UDP message version 2 have different layouts.
Reading the reference tables
Start with How the Hub processes data for the source and meaning of the measurements. Then use the chapter for your interface. Versions are listed from oldest to newest within each message type.
In the field tables, Type gives the stored size and signedness, Name identifies the field, and Scale converts the stored number to the listed Unit. The Description column explains offsets, packed bits, and other exceptions. Each format chapter explains its byte order and packet structure before listing the fields.
A status flag is one bit that describes a condition, such as whether a sensor is healthy. A mask identifies that bit. For example, a mask of 0x04 is set when status & 0x04 is nonzero. Status tables identify the byte to test; byte numbering starts at zero.
For technical assistance, contact support@bolderflight.com.