PPM / CPPM Receiver

Hi,

sorry if this may have been asked before: I am looking to simplify a multicopter build using the naze32 flight controller . My TX is a Devo 8s using Deviation. I am trying to find a receiver that can output PPM or CPPM (not Spektrum), but so far without much luck. Is there a receiver available that could do that? Having such a receiver would allow using a GPS in parallel. Normally I am using a spektrum satellites, this is unfortunately using the same PINs as the GPS. So right now I am back on Spektrum AR6115e with single cables.

Any hints would be great.

Thanks, Oliver

There is really no way around an RX with PPM output to be able to use the naze32 to its full extend. So I did some googling. Here is what I found in regards to being able to get PPM out of a receiver that can be used with deviation.

As I see it the only RX natively having PPM is going to be a FrSky, as soon as this is supported.

So as feasible workaround I was trying to find a way to have my Spektrum RXes output PPM. This would even work without installing a new module in the TX.

To make a long story short, the only remaining Spektrum 2 PPM Adapter left seems to be the 1hoch4 solution - but they are out of stock. Luckily I was able to find an unused one in the community. I will post my mileage here.

Of course, there are other solutions, most of them I did not favor. The LemonRX seemed nice at first, but I it only mentions 6ch and I did not get an answer from them if 6ch is a limit for PPM as well. Detlang has the same, but they explicitly say only 7ch max on the PPM signal. And the PWM to PPM diode thing, or an extra atmel reencoder, did not really seem to be an optimal solution. Following are the links. What really surprised me is that it is so difficult to get that PPM out of an RX, even on alternative products. From what I know Graupner is known to do 16 channely on PPM (40ms), encoders for arduino are freely available. How come that this is not available, even though many talented people have worked on it. But a small, cheap, lightweight PPM Output RX does not seem to be available - ok, I forgot FrSky here. Crossing my fingers on this one.

Please share, if there are other solutions and/or opinions. I am quite new to the RC hobby. Thanks, Olli

1: PWM to PPM Adapter - possible with all Receivers.
http://info.tt-rc.de/wiki.php?file=recenc.txt

2: Spektrum Satellit Serial Out in PPM Adapter:
http://www.1hoch4.net/shop/product_info.php?cPath=29&products_id=41

3: "Speck Drum" RX do it yourself:
http://www.mcselec.com/index.php?option=com_content&task=view&id=261&Itemid=57

4: Custom Spektrum RX with PPM Output:
http://www.lemon-rx.com/shop/index.php?route=product/product&path=70&product_id=66

Custom RX by Deltang:
www.lipoly.de/index.php?main_page=produc...4&products_id=259971

General Infos:
Protocol Out at the Spektrum Satellite: http://www.rcgroups.com/forums/showthread.php?t=922566
Spektrum Satellite -> Arduino -> PPM Out: http://www.dogfight.no/2011/01/spectrum-receiver-satellite-to-arduino.html
Find PPM out in the RX (not spektrum): http://rcarduino.blogspot.de/2012/11/how-to-read-rc-receiver-ppm-stream.html

Hi Olli,

I'm afraid this post won't help you, but I wanted to chime in and say that i'm in the SAME boat as you, except i'm running devo10.

I too am looking at the naze32 and would like to take advantage of PPM rx input.

However, I'm not sure I understand why you're saying that the lemon rx (PPM+UART version) will not work? Is it because you wanted more than 6 channels?

Do you know if my devo 10 will support PPM (I'd like to use that lemon rx) without any hardware changes to my Tx?

Is it as simple as selecting PPM in my model setup and hit re-init?

Thanks so much.
And just so you're aware - it looks like the lemon guys are working on a 10 channel satellite receiver... that might be another option?

Does it have to be DMS/DMX ?

There is the FlySky RX 8ch PPM maybe other option soon and built off PB hardwork

www.rcgroups.com/forums/showthread.php?t=1921870

www.rcgroups.com/forums/showthread.php?t=1798913

You are confusing things here.

A CPPM (or PPM sum) receiver has the ability to output all channels on a single wire and not use separate wires for each individual channel.

When selecting PPM on your radio, as a protocol, then your Devo 10 outputs PPM on the trainer port and does not use the internal radio module(s).

So they are 2 very different things.

Keep in mind though that not all PPM receivers are created equal. Some older FrSky receiver use a non-standard frame size and getting more than 8 6 channels out of the PPM stream is impossible not safe. Newer ones (or upgraded/reflashed) use a lengthier frame (~27ms) and 10 8 channels are possible is safe. But, FrSky is not yet supported by Deviation so this is a non-issue.

If you intend to size your equipment, my advice would be not to bet on more than 8 usable channels. This is what normally PPM outputs in a frame (~22ms IIRC).

ummagawd wrote: Hi Olli,

I'm afraid this post won't help you, but I wanted to chime in and say that i'm in the SAME boat as you, except i'm running devo10.

I too am looking at the naze32 and would like to take advantage of PPM rx input.

However, I'm not sure I understand why you're saying that the lemon rx (PPM+UART version) will not work? Is it because you wanted more than 6 channels?

Do you know if my devo 10 will support PPM (I'd like to use that lemon rx) without any hardware changes to my Tx?

Is it as simple as selecting PPM in my model setup and hit re-init?

Thanks so much.
And just so you're aware - it looks like the lemon guys are working on a 10 channel satellite receiver... that might be another option?

SadSack - For my application, I don't need any more than 6 channels.

sbstnp - thanks for clearing that up. I knew what CPPM was, but I didn't know that selecting PPM outputted the signals off the trainer port. (But good to know I can use it for a simulator then?)

So I guess what i'm hearing is that deviation supports CPPM, but NOT over DSM2/DSMX protocol?

And that the only other Rx out there that supports CPPM is FrSky.

BamFax - the Naze32 supports spektrum satellite receiver (so long as you can feed it a 3.3v source). You don't want to go that route? I originally wanted to avoid due to the extra work of making an adapter, but it seems like the only choice right now.

Yes you can use it with a simulator.

CPPM isn't a feature of _any_ protocol but a feature of receiver software+hardware. Software in the receiver MCU converts the channel data received over RF into a PPM stream and outputs this stream to a pin (hardware).

Most manufacturers prefer not to implement CPPM in their receivers. I know only of FrSky, Lemon and I think Futaba has/had select receivers with this feature. Don't know about JR/Hitec though, but Deviation doesn't support DMSS or AFHSS.

ummagawd wrote: sbstnp - thanks for clearing that up. I knew what CPPM was, but I didn't know that selecting PPM outputted the signals off the trainer port. (But good to know I can use it for a simulator then?)

So I guess what i'm hearing is that deviation supports CPPM, but NOT over DSM2/DSMX protocol?

sbstnp - thanks for that clarification. So does that mean that the receiver itself would need to be configured (a jumper?) to output PPM?

Okay just so I can get it straight once and for all... can I or can I not use the lemon rx (PPM+UART) with my deviation devo 10?

(i wasn't sure if you had implied that JR/Hitec rx's do PPM except they work over DMSS/AFHSS , which is something that deviation doesn't support)

thanks so much... you're saving me a lot of headache.

Yes, you can use the Lemon with your Devo 10.

Output to PPM is done either by configuring the receiver with a jumper like you said, or by using separate pins. You will most likely see when you get the receiver.

ummagawd wrote: sbstnp - thanks for that clarification. So does that mean that the receiver itself would need to be configured (a jumper?) to output PPM?

Okay just so I can get it straight once and for all... can I or can I not use the lemon rx (PPM+UART) with my deviation devo 10?

(i wasn't sure if you had implied that JR/Hitec rx's do PPM except they work over DMSS/AFHSS , which is something that deviation doesn't support)

thanks so much... you're saving me a lot of headache.

Nice! I might pick up one of those to use as a wireless simulator device.

Cheers

thanks sbstnp - you just made my day! (happy 4th BTW)

This will be perfect for my lightweight acro build.

I'm assuming then that bamfax needed 6+ channels and is why he's skipping the lemon option

And yea... i don't know why i automatically assumed I can't use this with a sim... but i'm totally getting one now.

Hi ummagawd,

good to see there's activity again in this thread. And good to see that I am not the only one, thanks for your reply.

An RX with PPM output is necessary when you are running out of UARTs (serial ports) and/or Input/Output PINs on your Flight Controller. The not-so-expensive FCs like a NanoWii or Naze32 just have a limited number of UARTs and PINs. For example, the Naze32 has three UARTs. I have a somewhat extended setup with all UARTs in use right now:
1. Spektrum Satellite
2. GPS
3. OSD

RX PPM Input just uses one analog PIN. It will free up the UART, to be used with for example 3DR Radio. I could also do traditional PWM input with each channel on a separate PIN. But being a fan of the MWii Serial Protocol, I want to keep as many PINs of the FC free to be used for analog INPUT.

So the best option is to use PPM to have the RX feed into the FC.

To have said this, another option would be to use the TX trainer port to connect a different module like FrSky or an LRS, but the trainer port is also where the FPV goggles headtracker connects to.

So what are the options to have PPM Output on the RX (using mighty deviation)? I was hoping the FrSky support would soon be here, as people are saying good things about its range, compared to spektrum. But this might no be true anymore with using different TX and RX hardware. And that is off topic anyway. I have not heard about the PPM trouble sbstnp pointed out, only thing I know that old FrSky PPM had the sync frame missing, and I know some people happily using FrSky PPM on the Naze32. But, hearing what sbstnp sais and since it's not supported by deviation, it's not really interesting right now.

Because there are other options. Sorry for being a little lengthy here
- Lemon RX: 6 channels on the PPM output only. Also it has a resolution of 256 steps, where a normal spektrum RX has 2048 steps.
[url=http://http://diydrones.com/profiles/blogs/lemon-rx-uart-and-ppm-output][/url]
One may argue that my stick fingers do not resolve to more than 256 steps, that I mostly agree, but I think the smoothness of steering might be noticable, especially in acro flying.
Also the new 10ch RX from Lemon does not have a PPM output at all. And it is fairly large, compared to a spektrum satellite.
All of that is from internet reading, I wrote them an email but did not get a reply.
- Right now I am using a 1hoch4 Spektrum2PPM converter. Setup: RX is a spektrum satellite on the copter (spektrum serial output here), connected to the converter (ppm output here), which is connected to the FC. This works absolutely great. It has 9 channels in the PPM signal, all 9 can be used. Both satellite and converter are really small and light.
- If everything works out well, a DSM2/DSMX RX will be commercially available in the near future with PPM Ouput having 12 ch and RSSI signal. Possibly I will get to test drive a prototype in August (if I get lucky). So, crossing my fingers here, that will be the solution I was hoping for. I will let you know if that works out.

Ok, that was maybe a little lengthy, but I hope it did shed some light on that topic.

Cheers,
Oliver

ps. You may ask "why bother about UARTs, channels, etc". The Harakiri firmware by Rob/CrashPilot1000/cGiesen(and others) for the Naze32 has tons of features, were those channels can be put to use: AltHold, GPS PH, Waypoints coming up, MWCGRB, Mavlink implementation coming up, Autolanding+Sonar, etc.

FWIW my 2c, on a quadcopter Multiwii controller I am using the FlySky HK-T6A-V2 with PPM out bound to Devo8s using V911 mod. Yes there are some of these rx's that have 6ch PPM out, this I have only tried in close proximity in an open field and works perfectly, I haven't tried further than 100m. I have ordered the 6ch Lemon-rx one that has PPM out but not yet received, they are about 2 weeks off, when I get them I will post back how successful I am. Aside, I don't use the trainer ppm on the tx for anything, in the next week or two I am going to hardwire in a diy frsky module to the tx ppm to get over the 6ch limit of flysky and lemon-rx and use the frsky stuff seamlessly then. Once done I will post about that.

I just tried a FrSky DJT Module I had lying around on my Devo8s, I hardwired from the tx battery, LiFe 6.6v, and the ppm trainer. It works perfect, not that I doubted it would but if anyone was interested. The DJT Module please be careful with if you do this, it's only good for 6v-13v so a Devo10 would be more practical or run a separate battery and common ground. Using my tx LiFe is fine as long as I keep an eye on the voltage. I haven't done range tests, but connected like this as an external module with it's own standard arial should be as good as in any other tx installation so should be fine.

Just a quick report back, got the Lemon-rx stuff, sadly the uart/ppm version does not work with with the KK2.0 board or Multiwii 328p board in with the cppm out. I haven't gone fully into the Multiwii sketch yet, maybe I can tweak something there but certainly out the box nothing - will check on the weekend and report back any success. The Lemonrx satellite does work perfectly in the Multiwii 328p but that was to be expected, convenient as its dirt cheap. Problem using the satellite on this specific board is that you then can't use the usb to the pc simultaneously neither could you use the bluetooth setup simultaneously, bit of a headache when setting up new quads. I see the brand new cppm FrySky rx on Hobbyking does every damn protocol except what we need lol! Ag one of these days

how can they market them as PPM if it does not support it? i just looked at some of the lemon rx on whitspy site and they say they support ppm...wth?

Hi Steve,

thanks for your update. I kind of shied away from the LemonRX as I read the info about the resolution of their PPM. But I would not have excepted that it does not work with MWii.

@Marty: PPM comes in several flavors and quite some implementations are not compatible. FrSky also had issues (in the beginning at least). So this is not really a surprise.

I have not yet received the RX I was talking about, I will let you know when i have anything new.

Olli

Steve or Bam - I just want to make sure I understood correctly...

You wired up an FrSky module to your devo 8?

How would I go about doing that to my devo 10?

AND... if one is able to do that... then in theory... shouldn't I be able to use this:
www.hobbyking.com/hobbyking/store/__2709...igy_compatible_.html

For myself, I checked the voltage was going to be compatible firstly with the module, in my case borderline on the low side, but for testing my idea it was fine. Only after that then it easier than opening a coke, you connect black and red to battery and the ppm to the ppm signal of the transmitter. In model selection just use ppm out.

I am completely unfamiliar with the LRS module and what inputs it expects as well as the correct low/high ends of voltage input. You could run a separate battery externally for the LRS module but be very very careful, only do this if you are 100% confident you know what you are doing, keep the black common, ppm stays with ppm (if the LRS uses ppm) and do not connect the two red + ever between the tx and external battery. By the time you are finished this you may be left with a monstrosity ...
Another thing, if you are going to use the ppm out like this, there is huge chance you will loose head tracking functionality. Do note the LRS is not entirely plug n play & HK warns that you need to know some programming & Ardunio.

Although I am completely fixated with Deviation and my Devo radios, for what you are looking to do, myself personally, I would just use a radio directly compatible with the LRS module. There is decent software available for the 9x and 9xr that is similar to Deviation where this project got it's roots. I still keep two older 9x radio's around, one heavily modded with a motherboard from www.ersky9x.net/ & FrySky with full telemetry and one standard with open9x software. For the price, why not

Think about it, toss up all your options and remember the head tracking thing ...

stevecox wrote: Just a quick report back, got the Lemon-rx stuff, sadly the uart/ppm version does not work with with the KK2.0 board or Multiwii 328p board in with the cppm out. I haven't gone fully into the Multiwii sketch yet, maybe I can tweak something there but certainly out the box nothing - will check on the weekend and report back any success. The Lemonrx satellite does work perfectly in the Multiwii 328p but that was to be expected, convenient as its dirt cheap. Problem using the satellite on this specific board is that you then can't use the usb to the pc simultaneously neither could you use the bluetooth setup simultaneously, bit of a headache when setting up new quads. I see the brand new cppm FrySky rx on Hobbyking does every damn protocol except what we need lol! Ag one of these days

on your KK2 board what firmware are you running? there has been a resent release firmware that supports CPPM...RC911 on rcg built custom firmware that works as cppm....its the 1.6++ cppm
www.rcgroups.com/forums/showthread.php?t=1915476