Jeti Telemetry should be possible now with the stm32 using the new Jeti EX-Bus protocol.

[Olivier ADLER]

I've seen a thread in the px4users forum talking about Jeti telemetry implementation.

https://groups.google.com/forum/#!topic/px4users/WMFk8UGfHNE


In short, Jeti Duplex EX telemetry protocol is not compatible with the STM32 because it is 9 bits + parity, this mode is not supported in hardware by the STM32 UART controller (the AVR Mega UART does support it).


But the newer Jeti EX Bus is 8 bits 8N1 at 125 or 250 kBaud, so it should be compatible. Jeti Duplex EX (the Jeti telemetry protocol) is embedded inside Jeti EX Bus.


Another advantage of Jeti EX-Bus is that it does carry high resolution 16 bits servo outputs (resolution = 1/8 us) at 50 or 100 Hz at the same time as telemetry, so there is no need for two connectors to connect a Jeti receiver to a flight control board, a single wire and a single UART is enough for servo data + bidirectional telemetry transfers.


I join the Jeti EX bus specification if someone wants to work on it. It is open.


I join as well the EX Duplex telemetry protocol, now embedded inside EX-Bus. Ex-Duplex is the telemetry part of EX-Bus, without any modification except that it is now embedded.


Jeti will release a lower cost DS-14 transmitter in 2014, this will be an opportunity to switch to Jeti for users that can't afford a DS-16 or DC-16.


Another important point, the latests Jeti DS-16 and DC-16 transmitter firmwares (v 2.20) has enabled a 8 channel PPM input on transmitters. This open the door to channel extenders, optional Joysticks for camera control, and why not sending Mavlink commands through PPM channels.



Another new option in this firmware is the possibility to switch the PPM output to Duplex EX output, so that it is possible to get EX telemetry output on the PPM connector.


This mean that it is now possible to have a bidirectional telemetry link embedded inside a 2.4 Ghz link using Jeti transmitters.



 Olivier

[Roberto Navoni]

That's a good news :)


2013/10/8 Olivier ADLER <cont...@nerim.net>:

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[Peter Plischka]

Hello Olivier,

Here you can find a few more information.
Maybe it will help you further.

http://code.google.com/p/arduino-jeti-communication/w/list

Regards Peter

[Olivier ADLER]

Thanks Peter. This is a good basis for Jeti EX-Bus as this protocol is embedded inside the newer EX-Bus.


There is a work here as well


https://github.com/diydrones/ardupilot/tree/master/Tools/ArduPPM/WorkBasket/Jeti_Duplex

[Peter Plischka]

I have a Jeti DC-16 and have installed a MU3 EX sensor in my copter  for battery voltage display.
Here in Germany many pilots are flying with a Jeti system.

Jeti Duplex EX telemetry during PIXHAWK  UART is a great solution.

Regards Peter

[איתי גיא‎]

Hi, 

what do u mean doesn't support 9 bits + parity  - did u mean 8 bit for data + one for parity , or 9 bits for data +one for parity ?

[Radek Voltr]

I did solution which can little help - http://www.devfor8.com/mav2duplex/

It is external convertor for MavLink data to Jeti Ex Telemetry Protokol. It is not fully mature and there is couple of bugs but it is open source :-)

But for questions - yes, communication is 9bit for data, Odd parity and 2 stop bits. Speed is 9600. I have to check if external devices like Jetibox Profi support it or you can use it only with their receivers.

On my blog is link to sources with SoftwareSerialO2 which is modification of software serial with such strange comm type.

One warning - there is two protocols from Jeti. One (Telemetry) is slow and second (EX Bus) is fast. But Ex Bus is primary designed for receivers, not for telemetry. Telemetry is still same.