How to set up PPM input in F405 WING

Hi,I got a problem for useing ULRS in F405 wing .The ULRS receiver will sent the PPM signal to the F405 WING,so the PPM signal is connect to the RX2 which is the PPM input pad of F405 wing ,but it doesn’t work ,I guest we have to setup some parameter to let the F405 know the PPM signal as the control signal,but i can’t find out any parameter to change the RX2 pad as PPM input signal .Does anybody know how to set up this parameter?
The F405 WING has installed arduplane firmware 3.9.9

no parameter required, just connect your receiver’s signal wire to the Sbs pin. this is used as RCIn, the ardupilot code will autodetect PPM / Sbus.

cheers, basti.

the ppm signal problem is OK now ,but there’s another problem i can’t find out any reason on google.The ULRS CC can’t receive any mavlink pockets ,and it can’t connect to mission planner by TTL.

imho it‘d be useful to add a wiring diagram showing how you got things connected, plus your current param file.

mind that afaik ULRS RX expects 19.200 baud on serial connection, while ardupilot telemetry port baudrates default to 57.600

double check your board‘s SERIALn_ parameters for correctness.

I wonder how he got the ppm working. It’s supposed to just work but mine don’t. I have F405 Wing with a ppm encoder connected between the pwm outputs of my receiver and Rx2 pin.
This one:

Ardupilot doesn’t see/communicate with it at all. It it not compatible with the f405? Or can I set a parameter somewhere and make it work?

imho all available documentation is pretty clear with regards to the default RCInput being the SBus pin:

Ok thanks for the reply! But, this encoder puts out ppm not sbus, and the Rx2 is connected to the sbus pin the difference is it’s not inverted? Anyway I’ve tried the sbus pin also, still nothing. I originally bought this:

And connected to the sbus pin also with no rcinput being detected in mission planner. I’ve tried inverting the signal in mission planner and changing the baud rate then when none of it helped I reset to defaults. Any ideas would be appreciated!
If not I’ma buy an APM 2.8 cause it’s supposed to have an integrated pwm to PPM encoder, just no osd, (and I didn’t wanna “muck about” with MinimumOSD,) but…

see the docs for reference. your MatekF405-Wing’s SBus pin is the default RCInput pin and will auto-detect PPM and SBus.

the linked converter‘s manual says:

  1. When one of CH1-CH8or some of CH1-CH8 input PWM signal, CH9 will output PPM signal and CH10 output SBUS signal. (LED Indicatorflash 1 second)

1.: can you confirm a 1 second flash on your converter‘s LED when you got everything hooked up and powered?

2.: if so, can you confirm your converter’s signal pin no 9 (“SBUS IN / PPM IN-OUT”) is connected to your flightcontroller’s “SBus” pin (including ground and 5V connections if required)?

3.: if not, can you provide an image of your wiring schematic and confirm you have not set any parameter affecting RC input away from default?

APM 2.8 has been retired for years, it’s long deprecated, unsupported hardware. you’ll sure find a better way. imho the most obvious solution would be to use an RC receiver with sum signal output.

Yes my converter has one second flash as soon as I turn on the transmitter and receiver starts getting a signal. I believe it also does a one second flash every time I move one of the sticks. I’ll double check that but I’m not by the transmitter right now it’ll be tomorrow. Yes number nine is connected to sbus. And ground and 5 volts.
Here is my wiring setup:

And a screenshot of mission planner:

I have tried changing serial2_protocol to 23 (and “write params”) but that did not help.
Obviously I’m missing something or I’m just flat wrong and that’s why I’m asking for your help. Some part of what I think I’ve done I must have not accomplished correctly just tell me what the obvious answer is and I’ll try it again!

Unless you have BRD_ALT_CONFIG set to 1 the Serial 2 settings will do nothing. It’s configured as Sbus/PPM input already with no parameters required to change.

Mine is set to zero. So should I change it to 1?
And then set serial2_protocol to 23?
( because this isn’t working)
Just wondering…

I would suspect the problem would follow but you could try it. Read the RC Input section here because you will have to wire to a different input.

What is that receiver?

The receiver is a dirty little secret. I’m still on 72 MHz. I haven’t decided which 2.4 GHz system I want because there’s so many options it’s confusing. I think I want a radiomaster tx16s with a TBS crossfire system. Full size preferably. But I haven’t gotten willing to spend all that money. I was trying to get a system working on this and then after a flight controller “functions” for me and I’ve gotten up a little speed I’ll invest more money. To buy hundreds of dollars worth of hardware when can’t even get this to work seems silly, so the receiver has six channels pwm output. And that’s what I’ve got to work with. I’d rather go try an antiquated APM that will work with this receiver and then after I’ve gotten in the air and want more options it will seem worth spending all that money on the new system. Long answer short answer whatever that’s where I’m at. So far I could use this flight controller for an OSD board and just control the plane manually. If I can’t get this to work that’s what I’m going to do.
I’ll take your suggestion and reread the RC input section that you linked in the meantime :+1:t2:

Ah OK, that’s why it looks so clunky. But if it’s what you have…

The Radiomaster would be a good choice. After some years with a Frsky Taranis, which I liked a lot, I switched. I use Frsky R9 but if I was starting with nothing I would go with Crossfire.

So if I set BRD_ALT_CONFIG=1 and configure SERIAL7=USER=USART2, what pin on the board would I connect RC input to?

In this case, the UART2 RX input (marked RX2 on the board) is used for the receiver input

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Ive thought about this for a minute. …
I’m in the USA. I just want to find someone I can send this whole setup to and they can tell me what’s broken or get it to work! One thing I have not disclosed is that I bought this f405 Wing off of eBay used. Everything seems to work as near as I can tell except this. I think it’s a good board but that is one unknown.
I could send everything except the receiver and they could use any receiver with pwm outputs.

PM sent.

Adding more characters.

@SpaceTrucker29 thanks for providing those images! what i would do is try and debug sytsematically, that is:

1.: make sure the flight controller is working as expected by trying with a known good PPM signal (from a known good receiver). if not, reflash the flight controller from scratch again and retry

2…: make sure the converter is working as expected by checking for correct PPM output with an o-scope. don’t know if you have the required hardware at hand though.

on a sidenote on all your images the converter’s LED is lit. might be coincidence, but if it really is constantly lit, that would indicate it’s not getting a valid input signal for whatever reason.