Bluetooth NMEA Strings

Profile > Equipment > Bluetooth Devices

Gaggle reads Bluetooth device data as a serial stream. When the stream contains NMEA-style sentences that start with $, Gaggle parses the sentence and uses any supported values while recording.

How the stream is read

Gaggle waits for Bluetooth notifications from the connected device, decodes the bytes as UTF-8 text, and builds a sentence when it sees either:

1. a new $ character
2. a newline character

Carriage returns and newlines are ignored between messages. If a device sends an unsupported sentence, Gaggle keeps the connection alive and reports that the sentence was ignored.

Standard GNSS sentences

Supported position-related sentences include:

1. $GPRMC - position, speed, heading, and timestamp
2. $GPGGA - GPS fix position and altitude
3. $GNGGA - GNSS fix position and altitude
4. $GAGGA - Galileo fix position and altitude
5. $GLGGA - GLONASS fix position and altitude
6. $GPGSA - satellite solution metadata; parsed but not used for a flight value

Vario and pressure sentences

Supported vario and pressure sentences include:

1. $LK8EX1 - pressure, vario, and ambient temperature
2. $BFV - BlueFly pressure, vario, and ambient temperature
3. $BFX - BlueFly extended pressure, vario, ambient temperature, and battery fields
4. $PDGFTL1 - DigiFly AIR vario data
5. $D - DigiFly vario, pressure, and temperature data
6. $LXWP0 - LX vario data
7. $LXWP1, $LXWP2, $LXWP3 - LX configuration/status sentences; parsed but not used for a flight value
8. $POV - OpenVario pressure, vario, and ambient temperature

Engine and fuel sentences

Supported powered-flight sentences include:

1. $--RPM - engine RPM when the sentence status is valid
2. $--CHT - cylinder/head temperature when the sentence status is valid
3. $HFM - fuel level and ambient temperature
4. $IBPPG - Insight PPG RPM, CHT, and ambient temperature
5. $EMS - engine monitor pressure, fuel level, ambient temperature, CHT, EGT, and RPM

FLARM and traffic sentences

Supported traffic-related sentences include:

1. $PFLAU - FLARM operating and alarm status
2. $PFLAA - FLARM aircraft traffic details

Other supported sentences

Additional supported sentence types include:

1. $PGRMZ - Garmin altitude when the fix mode is 3D
2. $XCTRC - location, altitude, speed, heading, and pressure

Troubleshooting

If a connected Bluetooth device does not show the expected toggles or live values:

1. Start a flight recording; Bluetooth devices only connect after recording starts.
2. Confirm the device is sending complete NMEA-style sentences that start with $.
3. Confirm each sentence ends with a newline or that the next sentence starts with $.
4. Check whether the sentence type is listed above.
5. If the device uses a proprietary sentence not listed here, Gaggle may ignore it until support is added.