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Hello everyone,
is it possible to somehow make the ExpressLRS module work with the Turnigy 9x? It needs CRSFShot protocol to work.
This would be awesome as my 9x is still working great and I don't really want to upgrade if not strictly necessary.
BTW thanks Mike to keep our radios alive
Cheers

Mike has announced that the er9x is in maintenance model: https://openrcforums.com/forum/viewtopi ... 50#p153461

But indeed the ability to use an ELRS external module would be great, as my Turnigy 9X is also in great condition. Any hint on where to look in the erskyTx code if I want to give it a try to port the protocol to er9x would be helpful too. Thanks!

The M64 version of er9x doesn't have flash space to add anything else.
Unfortunately, CRSF uses 400000 baud serial data, and the 9X doesn't have hardware support for serial, it has to "bit bash" a signal to generate serial data (the designer used the wrong processor pin, should have used one a timer could drive). The processor cannot handle such a high bit rate (a bit change every 2.5uS) while doing everything else it has to do.

Mike

Thanks Mike for the detailed answer!

MikeB wrote: ↑Tue Oct 26, 2021 2:21 pm Unfortunately, CRSF uses 400000 baud serial data, and the 9X doesn't have hardware support for serial, it has to "bit bash" a signal to generate serial data (the designer used the wrong processor pin, should have used one a timer could drive). The processor cannot handle such a high bit rate (a bit change every 2.5uS) while doing everything else it has to do.

Mike

Hi Mike,

The ELRS 2.0 just released and I was reading the release notes. And I realize it supports 115200 baud rate. I wonder if the MCU on the 9X can handle 115200 baud rate. It might be longer latency compared with the 400k baud rate, but if 9X can support 115200 baud rate, at least that enables ELRS on 9X and people like me can't really feel the latency difference anyway. But the long transmission distance/robustness of ELRS is still valuable. Thanks!

Thinking more carefully, ELRS uses the Crossfire protocol. This uses pin 5 (the bottom pin) of the module connector as bi-directional serial.The serial data also needs to be inverted as it is inverted on (for example) the FrSky Taranis, but kept at 5V (logic) levels.

It may be possible to design a hardware mod to achieve this, and it may be possible to get the '128 or '2561 processor to drive the signals (using the telemetry serial connections). However, this is quite a lot of work, and I already have several projects on the go.

Mike

speak man, came you've seen if it worked to use the expressLRS in the 9x, because I'm wanting to use it in my 9x. I'm looking forward to using it with LRS