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PPM Frame size

Posted: Thu Aug 27, 2015 5:40 pm
by afon
Hi All,

I have Turnigy 9XR + FrSky DJT + FrSky D4R-II

D4R-II was flashed with 27ms firmware because I want to use 7 channels.

My question is: what PPM frames size should be set in TX settings (openTx or er9x)?

At this moment in my TX settings I have (by default) PPM Frame 22.5ms 300u Negative

Is it OK?

I am not sure, that it is OK because D4R-II waiting for frames with 27ms size.

Re: PPM Frame size

Posted: Thu Aug 27, 2015 7:16 pm
by MikeB
How many channels are you sending, 8 I would guess since you want 7, and you have to choose either 6 or 8.
I would suggest allowing 2.1mS per channel and at least 4.5mS for the sync time so, for 8 channels, that is 8*2.1 + 4.5 = 16.8 + 4.5 = 21.3.
21.5 is the minimum to use so the default of 22.5 is fine.
The D4R generates the output CPPM using 27 mS, but this is independant of the rate sent from the Tx to the DJT.
So, 22.5mS is perfectly OK.

Mike.

Re: PPM Frame size

Posted: Thu Aug 27, 2015 8:26 pm
by afon
Hi Mike.

Thank you very much. Your answer really helped me to understand underlying settings.

I will leave PPM Frame size "as is" (22.5ms)

Re: PPM Frame size

Posted: Wed Mar 04, 2020 7:10 am
by Buzzliteyear
Hi Mike ,
can i use the same formula for 12 channels Sbus LRS and ER9x on turnigy 9x 12 x 2.1 + 4.5 = 29.7 + 4.5 = 34.2ms ?

no option above 32.5ms in my FW version

Brett

Re: PPM Frame size

Posted: Wed Mar 04, 2020 7:42 am
by Kilrah
What module?

Re: PPM Frame size

Posted: Wed Mar 04, 2020 9:29 am
by Buzzliteyear
Ebyte Lora module 433,
I just manager to hook it up and try and it wont work on selecting Sbus
is there Sbus output from turnigy 9x with er9x firmware?

Brett

Re: PPM Frame size

Posted: Wed Mar 04, 2020 9:34 am
by Kilrah
If you output SBUS then PPM timings have nothing to do with it...

Re: PPM Frame size

Posted: Wed Mar 04, 2020 10:04 am
by Buzzliteyear
Ofcoarse .....i see now.....

i dont understand the sbus output, If i move the throttle it is like the gap in the first pulse increases

Re: PPM Frame size

Posted: Wed Mar 04, 2020 10:42 am
by MikeB
er9x does support SBUS, however this is "standard SBUS" currently that is inverted, logic 1 = 0V, logic 0 = positive voltage.
SBUS is sent at 100000 baud. Your logic capture is sampling at 20kHz (20000) so is not fast enough. To capture 100000 baud, you need to sample at least twice as fast as 100kHz, I would use a sample rate of 1mHz.
Does your module accept the inverted signal?

I make the PPM calculation:
12 x 2.1 + 4.5 = 25.2 + 4.5 = 29.7ms ?

Mike

Re: PPM Frame size

Posted: Wed Mar 04, 2020 12:37 pm
by Buzzliteyear
No it does not accept inverted signal I made this inverter with BC547,
I did another sample @ 1mhz after the inverter and got about 66 frames (only about 15 shown in pic below)... does that seem normal ?

Re: PPM Frame size

Posted: Wed Mar 04, 2020 7:09 pm
by MikeB
Your SBUS signal is not correct. You should see about 9 frames per second (1 every 11 mS), and the waveform should be a standard UART at 100000 baud, 12 bits per character, 1 start, 8 data, 1 even parity and 2 stop.
Try checking the signal from the radio, on the 9X, this is at 5V.
You might also check your connections to the BC547.

Mike

Re: PPM Frame size

Posted: Wed Mar 04, 2020 10:24 pm
by MikeB
I've just posted a test version of er9x that includes a polarity option for the SBUS protocol output.

Mike

Re: PPM Frame size

Posted: Thu Mar 05, 2020 6:09 am
by Buzzliteyear
Ok it is working

not sure why but this is the hookup

9x signal is inverted going through inverter = non inverted signal to Tx Lora module

Rx side = Rx Lora module feeds inverted uart 6 PPM/Sbus pin only ( not uart 1,3 or 6 on the left side on the omnibus F4 v3)

thanks heaps for the help Mike

Re: PPM Frame size

Posted: Thu Mar 05, 2020 7:16 am
by Buzzliteyear
822c ? I just flashed that cant see polarity option............

https://openrcforums.com/forum/viewtopi ... 598#p64969

Perfect Works Great thanks again........dont need that invertor now.......where the donate button :)

Re: PPM Frame size

Posted: Thu Mar 05, 2020 10:10 am
by MikeB
There is one on here: https://github.com/MikeBland/mbtx, or "jhsa" has a link at the bottom of his posts.

Mike

Re: PPM Frame size

Posted: Fri Mar 06, 2020 2:43 am
by Buzzliteyear
Done cheers.......Brett

Re: PPM Frame size

Posted: Sun Jan 03, 2021 2:32 pm
by axljackass
MikeB wrote:
Wed Mar 04, 2020 10:24 pm
I've just posted a test version of er9x that includes a polarity option for the SBUS protocol output.

Mike
hi Mike,

Possible to include this to M64 9X?
Want to test this to my 9X with LORA module but i have M64.
Thanks.

Axl

Re: PPM Frame size

Posted: Sun Jan 03, 2021 3:35 pm
by MikeB
It should be there already. I've posted a new test version earlier today, so if you do not have the option, please try this test version.

Mike

Re: PPM Frame size

Posted: Sun Jan 03, 2021 11:36 pm
by axljackass
MikeB wrote:
Sun Jan 03, 2021 3:35 pm
It should be there already. I've posted a new test version earlier today, so if you do not have the option, please try this test version.

Mike
Hi Mike,

i supposed is this firmware.
er9xProv822w.zip
03-Jan-2021 11:31
Fix (possibly!) PC4(L-WR) not working as extra digital input
(1.07 MiB) Downloaded 2 times

can i check with you if the M'Sound serial also included inside this firmware.

Thank you for your support.

Re: PPM Frame size

Posted: Mon Jan 04, 2021 11:30 am
by MikeB
Yes MegaSound serial is included (er9x-frsky-sv.hex).

Mike

Re: PPM Frame size

Posted: Mon Jan 04, 2021 10:18 pm
by axljackass
MikeB wrote:
Mon Jan 04, 2021 11:30 am
Yes MegaSound serial is included (er9x-frsky-sv.hex).

Mike
Hi Mike,

Telemetry for s.port still need to use inverter or already converterted in the new firmware?
Thanks

Re: PPM Frame size

Posted: Wed Jan 06, 2021 9:46 pm
by MikeB
No, you will still need an inverter for the SPort telemetry. On the AVR processor, it is not really possible to invert this in firmware.

Mike

Re: PPM Frame size

Posted: Thu Jan 07, 2021 7:00 am
by axljackass
MikeB wrote:
Wed Jan 06, 2021 9:46 pm
No, you will still need an inverter for the SPort telemetry. On the AVR processor, it is not really possible to invert this in firmware.

Mike
Noted.
Thanks.

(",

Re: PPM Frame size

Posted: Fri Jan 08, 2021 4:12 am
by axljackass
Hi Mike,

Just want to report something.

While im waiting for my 0ohms smd resistors, to be use for arduvoice voice mod, i decided to return back to non mod firmware for my M64 turnigy 9x radio.
I downloaded the M64 Frsky and Standard versions from ER9X website but after i flashed i noticed no beep sound after flashing, something was not right.
Then i compiled for my M64 and after flashing there was a beep sound.
Also the Test Version have beep sound after flashing.