Hello guys, 

I've replaced my Fly Sky 6 channels for a Radiolink AT9 in order to use PPM, the goal here is basically don't use one wire per channel, something that locks most ports from the FC (led_strip for example).

Here is the deal:
- I have the radio
- I can see it's correctly bound
- I connect the 3 wires (signal, +, -) to the port 1, 
- I see it power the receiver
- I also see in the transmitter that the link is working because it shows the signal bars
- Changed Cleanflight setting to be PPM RX instead of PWM, 
- Tested also to switch the modes form the receiver PWM/SBUS by switching the led from red to blue/purple.

But nothing happens on the receiver tab in cleanflight.



Any suggestion on what I could review here ?
Thanks

What FC are you using?
and which RX are you suing with the AT9?

Links or pictures to both products please

(26-Apr-2017, 09:53 PM)Oscar Wrote: What FC are you using?
and which RX are you suing with the AT9?

Links or pictures to both products please

Hi Oscar, 

The RX is R9DS from Radiolink also.

Looks like something went wrong here. As a test I tried to connect it as PWM (one wire/channel) and now looks like the FC is bricked. (Naze32 Rev5).

When I power it with the battery the ESCs don't play the start jingle anymore, I removed the RX already and the behavior remains.
Before moving forward with the PPM stuff I need to bring back the FC.

CleanFlight is no longer recognizing it, If I try to flash firmware again it says : NO RESPONSE FROM THE BOOTLOADER.

Any suggestion ?

Thanks

That sounds bad.

Carefully inspect the flight controller with a magnifying glass. It sounds like something is shorted.

If the ESCs don't play the full tune that they normally do, then they're not even seeing a signal from the flight controller which most likely means that the CPU isn't running.

Were you connecting with plugs and pin headers or soldering direct?

I was using the pin headers that come with the FC, so there is not much to do wrong,
The only light I see on the FC is the blue led (power) nothing else.

Is it getting hot anywhere on the flight controller? Did you accidentally short something when you were trying to get the receiver working?

It sounds like your flight controller is toast I'm afraid.

If it does somehow come back to life, the R9DS outputs either SBUS or PWM, so there's no point trying to connect it as a PPM receiver. The other problem is that you need to add an inverter to the rev5 Naze32 for it to be able to understand SBUS.

(26-Apr-2017, 11:38 PM)unseen Wrote: Is it getting hot anywhere on the flight controller? Did you accidentally short something when you were trying to get the receiver working?

It sounds like your flight controller is toast I'm afraid.

If it does somehow come back to life, the R9DS outputs either SBUS or PWM, so there's no point trying to connect it as a PPM receiver. The other problem is that you need to add an inverter to the rev5 Naze32 for it to be able to understand SBUS.

I was able to unbrick it by following the process described to re-flash the firmware with the boot pins with the jumper 
I´ll post later the wiring I´m using here for the PPM as originally requested by Oscar and I´ll appreciate your inputs!

Saved me $40 !!

(26-Apr-2017, 11:38 PM)unseen Wrote: Is it getting hot anywhere on the flight controller? Did you accidentally short something when you were trying to get the receiver working?

It sounds like your flight controller is toast I'm afraid.

If it does somehow come back to life, the R9DS outputs either SBUS or PWM, so there's no point trying to connect it as a PPM receiver. The other problem is that you need to add an inverter to the rev5 Naze32 for it to be able to understand SBUS.

Hi unseen, 

Yes is back after following the manual flash with a jumper on the boot pins, Im not sure what could caused that.
Anyway, what would you recommend me to do for wiring the receiver ? either PPM or SBUS could be done with Naze32 without the inverter ?

R9DS doesn't do PPM, only PWM and sBus.  If you're using sBus, you need to configure as such in Cleanflight.  Here's a good tutorial that Oscar did on setting up a Rev 5 with sBus
https://oscarliang.com/sbus-smartport-telemetry-naze32/

(27-Apr-2017, 03:33 AM)RENOV8R Wrote: R9DS doesn't do PPM, only PWM and sBus.  If you're using sBus, you need to configure as such in Cleanflight.  Here's a good tutorial that Oscar did on setting up a Rev 5 with sBus
https://oscarliang.com/sbus-smartport-telemetry-naze32/

I just bought the SBUS PPM inverter cable for doing this.

Thanks a lot !

(27-Apr-2017, 03:14 PM)flabombarda Wrote: I just bought the SBUS PPM inverter cable for doing this.

Thanks a lot !

Great, that should get you back on track when you receive it and I hope you ordered the right type of cable because "SBUS PPM inverter" doesn't really make sense.

It's really important in the RC world to get your terminology right, so let me offer a little explanation of what SBUS and PPM are. Both SBUS and PPM can be called 'serial protocols' as 'serial' implies that the data is sent over a single wire. PWM, where each channel from the receiver has its own wire is a parallel protocol.

However, although SBUS and PPM both use a single wire from the receiver to the flight controller, they are very different in how they work.

SBUS is a digital serial protocol originally developed by Futaba. It uses an inverted signal where a logical one is indicated by a low voltage and zero by a high voltage. It runs at 100,000 bits per second and sends 25 bytes per packet. The packet contains digital data for all 16 channels plus failsafe information.

PPM is an analogue serial protocol where a sequence of short, positive level pulses are sent in (generally) a 22.5 millisecond frame. The first pulse signifies the start of the frame and the time between each pulse indicates the channel value. After the pulses are sent there is a period with no pulses which must be longer than the longest valid pulse interval to mark the end of the frame.

PPM is never sent inverted. SBUS is always sent inverted. The cable you bought would correctly and simply be called an inverter cable. All it does is output a high voltage when it sees a low voltage and vice versa. The function of inverting a signal is not specific to SBUS, it's a general technique in electronics.

The advantages of SBUS over PPM are twofold:

It is much faster - 16 channel values can be sent from the receiver to the flight controller in just two milliseconds. A PPM signal can only send around half that information and it does it ten times more slowly.
Being digital, the SBUS protocol isn't affected by timing differences between the transmitter and receiver or by clock drift on the receiver or flight controller and therefore has higher accuracy and resolution.

There's no escaping from the alphabet soup that is specific to our hobby. There's a good overview of the various protocols used by RC receivers over on Oscar's blog: https://oscarliang.com/pwm-ppm-sbus-dsm2...ifference/

Learning the basic terminology that is used in the RC hobby is crucial. If you don't understand what the various acronyms mean, it's hard to communicate properly and you run the risk of buying the wrong thing if you don't understand what you need.

I hope this helps!

(27-Apr-2017, 05:22 PM)unseen Wrote: Great, that should get you back on track when you receive it and I hope you ordered the right type of cable because "SBUS PPM inverter" doesn't really make sense.

It's really important in the RC world to get your terminology right, so let me offer a little explanation of what SBUS and PPM are. Both SBUS and PPM can be called 'serial protocols' as 'serial' implies that the data is sent over a single wire. PWM, where each channel from the receiver has its own wire is a parallel protocol.

However, although SBUS and PPM both use a single wire from the receiver to the flight controller, they are very different in how they work.

SBUS is a digital serial protocol originally developed by Futaba. It uses an inverted signal where a logical one is indicated by a low voltage and zero by a high voltage. It runs at 100,000 bits per second and sends 25 bytes per packet. The packet contains digital data for all 16 channels plus failsafe information.

PPM is an analogue serial protocol where a sequence of short, positive level pulses are sent in (generally) a 22.5 millisecond frame. The first pulse signifies the start of the frame and the time between each pulse indicates the channel value. After the pulses are sent there is a period with no pulses which must be longer than the longest valid pulse interval to mark the end of the frame.

PPM is never sent inverted. SBUS is always sent inverted. The cable you bought would correctly and simply be called an inverter cable. All it does is output a high voltage when it sees a low voltage and vice versa. The function of inverting a signal is not specific to SBUS, it's a general technique in electronics.

The advantages of SBUS over PPM are twofold:

It is much faster - 16 channel values can be sent from the receiver to the flight controller in just two milliseconds. A PPM signal can only send around half that information and it does it ten times more slowly.
Being digital, the SBUS protocol isn't affected by timing differences between the transmitter and receiver or by clock drift on the receiver or flight controller and therefore has higher accuracy and resolution.

There's no escaping from the alphabet soup that is specific to our hobby. There's a good overview of the various protocols used by RC receivers over on Oscar's blog: https://oscarliang.com/pwm-ppm-sbus-dsm2...ifference/

Learning the basic terminology that is used in the RC hobby is crucial. If you don't understand what the various acronyms mean, it's hard to communicate properly and you run the risk of buying the wrong thing if you don't understand what you need.

I hope this helps!

Hi Unseen

Got the cable, and it´s working using PPM, just to clarify, is there any way I use it as SBUS ?

I tried to configure as SBUS, using the port 4 for the signal (instead of 1 using on PPM) and also configured the receiver for Serial -> SBUS, did not work.

Anyway, if PPM is the best I can do here, I´m fine !

thanks

I'm not trying to be impolite, but your post doesn't make sense. Are you sure you're using the R9DS? As I said in a previous post, it only outputs sBus and PWM signals, NOT PPM. If you could post a pic of your receiver and flight controller connections. I'm sure we can get you in the air quickly. I have a feeling your receiver isn't connected correctly

http://www.radiolink.com.cn/doce/product...l-120.html

(29-Apr-2017, 02:39 AM)RENOV8R Wrote: I'm not trying to be impolite, but your post doesn't make sense.  Are you sure you're using the R9DS?  As I said in a previous post, it only outputs sBus and PWM signals, NOT PPM.  If you could post a pic of your receiver and flight controller connections. I'm sure we can get you in the air quickly.  I have a feeling your receiver isn't connected correctly

http://www.radiolink.com.cn/doce/product...l-120.html

Spot on. If it was PPM, an inverter would make it stop working.

Maybe the OP actually purchased an SBUS to PPM converter? That's a useful compromise if you have a flight controller that doesn't understand SBUS, but it is a horrible compromise to take a protocol with 2ms latency and convert it into one with over 20ms latency when all that's needed is an inverter.

flabombarda, can you post a link to the cable that you purchased?

Guys, 

I understand your concerns here, I´ll post tomorrow few pictures of the whole setup, it may be easier to understand what I have and if some information I´m sharing is inaccurate.

Thanks