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156 lines
5.8 KiB
Markdown
156 lines
5.8 KiB
Markdown
# Telemetry
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Telemetry allows you to know what is happening on your aircraft while you are flying it. Among other things you can receive battery voltages and GPS positions on your transmitter.
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Telemetry can be either always on, or enabled when armed. If a serial port for telemetry is shared with other functionality then then telemetry will only be enabled when armed on that port.
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Telemetry is enabled using the 'TELEMETRY' feature.
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```
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feature TELEMETRY
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```
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Multiple telemetry providers are currently supported, FrSky, Graupner
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HoTT V4, SmartPort (S.Port) and LightTelemetry (LTM)
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All telemetry systems use serial ports, configure serial ports to use the telemetry system required.
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## FrSky telemetry
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FrSky telemetry is transmit only and just requires a single connection from the TX pin of a serial port to the RX pin on an FrSky telemetry receiver.
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FrSky telemetry signals are inverted. To connect a cleanflight capable board to an FrSKy receiver you have some options.
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1. A hardware inverter - Built in to some flight controllers.
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2. Use software serial and enable frsky_inversion.
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3. Use a flight controller that has software configurable hardware inversion (e.g. STM32F30x).
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For 1, just connect your inverter to a usart or software serial port.
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For 2 and 3 use the CLI command as follows:
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```
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set telemetry_inversion = ON
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```
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### Precision setting for VFAS
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INAV can send VFAS (FrSky Ampere Sensor Voltage) in two ways:
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```
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set frsky_vfas_precision = 0
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```
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This is default setting which supports VFAS resolution of 0.2 volts and is supported on all FrSky hardware.
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```
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set frsky_vfas_precision = 1
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```
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This is new setting which supports VFAS resolution of 0.1 volts and is supported by OpenTX and er9x/ersky9x firmware (this method uses custom ID 0x39).
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### Notes
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RPM shows throttle output when armed.
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RPM shows when disarmed.
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TEMP2 shows Satellite Signal Quality when GPS is enabled.
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RPM requires that the 'blades' setting is set to 12 on your receiver/display - tested with Taranis/OpenTX.
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## HoTT telemetry
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Only Electric Air Modules and GPS Modules are emulated.
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Use the latest Graupner firmware for your transmitter and receiver.
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Older HoTT transmitters required the EAM and GPS modules to be enabled in the telemetry menu of the transmitter. (e.g. on MX-20)
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Serial ports use two wires but HoTT uses a single wire so some electronics are required so that the signals don't get mixed up. The TX and RX pins of
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a serial port should be connected using a diode and a single wire to the `T` port on a HoTT receiver.
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Connect as follows:
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* HoTT TX/RX `T` -> Serial RX (connect directly)
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* HoTT TX/RX `T` -> Diode `-( |)-` > Serial TX (connect via diode)
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The diode should be arranged to allow the data signals to flow the right way
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```
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-( |)- == Diode, | indicates cathode marker.
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```
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1N4148 diodes have been tested and work with the GR-24.
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As noticed by Skrebber the GR-12 (and probably GR-16/24, too) are based on a PIC 24FJ64GA-002, which has 5V tolerant digital pins.
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Note: The SoftSerial ports may not be 5V tolerant on your board. Verify if you require a 5v/3.3v level shifters.
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## LightTelemetry (LTM)
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LTM is a lightweight streaming telemetry protocol supported by a
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number of OSDs, ground stations and antenna trackers.
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The INAV implementation of LTM implements the following frames:
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* G-FRAME: GPS information (lat, long, ground speed, altitude, sat
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info)
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* A-FRAME: Attitude (pitch, roll, heading)
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* S-FRAME: Status (voltage, current+, RSSI, airspeed+, status). Item
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suffixed '+' not implemented in INAV.
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* O-FRAME: Origin (home position, lat, long, altitude, fix)
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In addition, in the inav (navigation-rewrite) fork:
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* N-FRAME: Navigation information (GPS mode, Nav mode, Nav action,
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Waypoint number, Nav Error, Nav Flags).
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LTM is transmit only, and can work at any supported baud rate. It is
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designed to operate over 2400 baud (9600 in INAV) and does not
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benefit from higher rates. It is thus usable on soft serial.
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More information about the fields, encoding and enumerations may be
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found at
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https://github.com/stronnag/mwptools/blob/master/docs/ltm-definition.txt
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## MAVLink telemetry
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MAVLink is a very lightweight, header-only message marshalling library for micro air vehicles.
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Cleanflight supports MAVLink for compatibility with ground stations, OSDs and antenna trackers built
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for PX4, PIXHAWK, APM and Parrot AR.Drone platforms.
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MAVLink implementation in Cleanflight is transmit-only and usable on low baud rates and can be used over soft serial.
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## SmartPort (S.Port)
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Smartport is a telemetry system used by newer FrSky transmitters and receivers such as the Taranis/XJR and X8R, X6R and X4R(SB).
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More information about the implementation can be found here: https://github.com/frank26080115/cleanflight/wiki/Using-Smart-Port
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In time this documentation will be updated with further details.
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Smartport devices can be connected directly to STM32F3 boards such as the SPRacingF3 and Sparky, with a single straight through cable without the need for any hardware modifications on the FC or the receiver.
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For Smartport on F3 based boards, enable the telemetry inversion setting.
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```
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set telemetry_inversion = ON
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```
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### SmartPort (S.Port) with external hardware inverter
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It is possible to use DIY UART inverter to connect SmartPort receivers to F1 and F4 based flight controllers. This method does not require hardware hack of S.Port receiver.
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#### SmartPort inverter using bipolar transistors
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#### SmartPort inverter using unipolar transistors
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**Warning** Chosen UART has to be 5V tolerant. If not, use 3.3V power supply instead (not tested)
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When external inverter is used, following configuration has to be applied:
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```
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set smartport_uart_unidir = ON
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set telemetry_inversion = OFF
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```
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This has been tested with Flip32 F4 / Airbot F4 and FrSky X4R-SB receiver.
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