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        New Product Channel Wizard: Add/mix/encode/decode PPM channels

#1 FpvKiwi Jan 18, 2012 04:05 PM

Channel Wizard: Add/mix/encode/decode PPM channels
 
2 Attachment(s)
I'm proud to announce Channel Wizard, a small circuit designed to add RC channels to the "PPM" signals that's used for control in most RC vehicles. It can also perform a multitude of other tasks either on the ground or onboard the aircraft, such as combining multiple PPM sources, make PPM compatible with long-range UHF systems, decode PPM to servo signals or create a new PPM signal from switches and pots.

http://www.rcgroups.com/forums/showa...9&d=1327152740

This post is an overview. The manual has more info.

Add Channels
Connect Channel Wizard to the PPM stream between the Tx and the radio module. Wizard can be connected to switches and pots to add up to eight extra PPM channels. If the radio module can't handle enough channels, a "multiplexing" scheme is used to inject multiple inputs into one channel. Multiplexing also helps if the receiver doesn't have enough servo ports. When multiplexing is active, another Wizard is needed in the aircraft to extract the extra channels again. See Adding Channels for a more complete introduction.

Note that adding channels requires basic electrical skills and soldering in one way or another.

In the Aircraft
Channel Wizard can also be used in aircrafts to decode PPM to individual servo signals, reverse, change trim and EPA. Here the Wizard ports are used as servo connectors instead of inputs.

Hardware Features
Channel Wizard is designed to handle all common PPM forms and signal levels. It accepts voltage levels of 3.3-18 V so both trainer and module ports can be used, or the 5 V used internally in Tx'es.
For use in aircrafts, the circuit features power filtering to avoid brown-outs and protection against flipped servo connectors. The circuit is designed to be as small as possible: 8 grams and 40x30 mm (plus space for servo connectors) is about the size of a regular receiver.
Two push buttons and a wheel are used for setup.

Connect to Computer
Optionally use a serial cable and computer to make advanced settings, switch between transmitter and aircraft mode or upgrade the firmware. Advanced settings include combining multiple PPM input streams (for example headtrackers), treat PPM formats to make them compatible with LRS modules, generating sound, doing various channel mixing or doing control diversity (switching between two receivers to control all servos). This is setup with a powerful command line mode with dozens of commands and mathematical functions. In the future, the serial cable could also be used to control PPM from the computer.

Compatibility
Wizard has been tested with a number of transmitters and should be compatible with all major transmitter brands as long as the radio module accepts PPM. New 2.4GHz transmitters with integrated radio modules typically don't use PPM except for the trainer port. Multiplexing doesn't work with 35MHz or 72MHz radio links yet. Long-range systems are supported (including 12ch for DragonLink) as well as all standard receivers.

Ordering
Channel Wizard is available in limited quantity at the price $50. See Ordering details.

Comments are welcome!

Adding 8ch via Futaba trainer port:
Channel Wizard adding 8 ch. via trainer (1 min 11 sec)

#2 FpvKiwi Jan 18, 2012 04:06 PM

Availability Feb 2014: In stock. See http://www.rcgroups.com/forums/showp...&postcount=345 for details.

#3 Hugeone Jan 18, 2012 04:24 PM

Thx FpvKiwi for such a great product!
I used it to cure the variable PPM frame from my 12Z to feed the TSLRS correctly, work plug & play :)

-Hugo

#4 techspy Jan 18, 2012 04:37 PM

I have one on the way to be used with my 12FG and a LSLRS. Can't wait to give it a go!

#5 garris2 Jan 19, 2012 11:05 PM

Quote:

Originally Posted by Hugeone (Post 20464809)
Thx FpvKiwi for such a great product!
I used it to cure the variable PPM frame from my 12Z to feed the TSLRS correctly, work plug & play :)

-Hugo

Hi Hugo, does this Channel Wizard work with your 12FG and TSLRS/DragonLink without the need to go through and shorten all the channel travels down to a minimum?

Thanks
Geoff

#6 Hugeone Jan 19, 2012 11:57 PM

Quote:

Originally Posted by garris2 (Post 20478606)
Hi Hugo, does this Channel Wizard work with your 12FG and TSLRS/DragonLink without the need to go through and shorten all the channel travels down to a minimum?

Thanks
Geoff

Yep, at the cost of about 1 frame latency (28ms)

-Hugo

#7 garris2 Jan 22, 2012 04:51 AM

Hi Hugo, thanks for your reply.

That 28ms, is that noticble in any way, flight, pan/tilting, FPV landing etc?

Thanks
Geoff

#8 Hugeone Jan 22, 2012 07:39 AM

Quote:

Originally Posted by garris2 (Post 20499998)
Hi Hugo, thanks for your reply.

That 28ms, is that noticble in any way, flight, pan/tilting, FPV landing etc?

Thanks
Geoff

Not to me.

-Hugo

#9 FpvKiwi Jan 22, 2012 09:36 AM

Quote:

Originally Posted by garris2 (Post 20499998)
That 28ms, is that noticble in any way, flight, pan/tilting, FPV landing etc?

The lag comes from Wizard generating 28ms long PPM frames independently of the incoming PPM from the Tx. In the best case an incoming update comes just before generating that output channel, for just a few ms of added lag. In the worst case, the outgoing channel was sent just before an incoming update, leading to Wizard relaying that channel with the next output one 28ms frame later. This relative timing between Wizard input and output changes since the frame lengths are not exactly the same.

So the added lag continuously varies in the range 2-30ms. There are other sources of lag too in the system (Tx encoding, radio link, servo speed). This part alone shouldn't matter for regular flying.

For comparison, human reaction time in RC can come down to 100-150 ms (Source: Toysrme)
For comparison, human reaction time to visual stimulus is about 190ms. (Source: Wikipedia)

#10 Toysrme Jan 22, 2012 11:55 AM

i wub fpvkiwi. tho i thought kiwi's meant New Zealand and you're in Sweden?

#11 FpvKiwi Jan 22, 2012 04:18 PM

The reaction time I quoted was to give a perspective to the length of a millisecond. I didn't mean to imply that the average reaction time to a semi-random event is directly relevant to the lag in RC flying. However, neither is your discussion on computer gaming and what's worse, it's completely irrelevant to the topic of this thread.

Let's leave it at me standing corrected; 50 ms is a more reasonable lower limit on human visual reaction time. Everyone has to make his own decision what that means for his style of RC flying.

#12 Toysrme Jan 23, 2012 06:40 AM

can you detect +28ms worth of lag? it depends
1) on you
2) on your current radio equipment
radio equipment itself has input lag. a lot of transmitters in the last 10 years have extremely good performance (a stable 10-30ms). while other radio systems have poor performance. well exceeding 50ms and even worse many have lag spikes upwards of 100ms.
3) on your current video equipment. input lag in our case also must take into consideration the lag our video induces. name does the camera process the image & how much your viewing device is lagging.

so basically.

if your current radio & video equipment has a reasonable amount of input lag no. you're likely to never realize the additional 28ms. now, if you've got a really crappy tx/rx/servo+video system that's prone to just being laggy & having lag spikes well over 100ms. yes, another 28ms may push you over your personal edge that you decide. hey... im lagging.
if that's the case, it's still not this device's fault. it's all the other poor equipment that needs replacing.

#13 pr0ject42 Jan 23, 2012 10:35 AM

Holy crap this is so far off topic that it is silly. Toysrme, take your reaction discussion elsewhere, we are all adults and can do our own calculations on what our reactions times are. Lets be real, no one is doing 3D smackdown via FPV with a helicopter. That is a game of milliseconds. Flying your easystar is not.

I've got a question for you, fpvkiwi, I'd like to use your product (or something similar) to have to TX units getting mixed into one TSLRS transmitter that can be decoded by one TSLRS long range RX for the full 12 channels. I would imagine having the two TXes going out via the buddy ports or through module ports on futaba radios and peeling out the needed channels from each to be mixed into the one 12 channel PPM stream. Is this crazy talk or can your product do that? The idea would be one pilot with flight controls and a secondary "co-pilot" who would be using their sticks to move a camera gimble around. I don't want to hack into the transmitter itself.

Thanks man!

#14 FpvKiwi Jan 23, 2012 10:49 AM

Thanks Toysrme.. "wub", that was a new word for me. I'm no expert at human reaction times so the extra background info doesn't hurt. I updated my previous post. I agree with your conclusion, I've nothing to add really.

Myself, I prefer to fly with stabilization...

#15 FpvKiwi Jan 23, 2012 10:58 AM

Quote:

Originally Posted by pr0ject42 (Post 20512183)
I've got a question for you, fpvkiwi, I'd like to use your product (or something similar) to have to TX units getting mixed into one TSLRS transmitter that can be decoded by one TSLRS long range RX for the full 12 channels. I would imagine having the two TXes going out via the buddy ports or through module ports on futaba radios and peeling out the needed channels from each to be mixed into the one 12 channel PPM stream. Is this crazy talk or can your product do that? The idea would be one pilot with flight controls and a secondary "co-pilot" who would be using their sticks to move a camera gimble around. I don't want to hack into the transmitter itself.

Hi pr0ject42, no worries, we cleared it up and I learnt something. As long as we stay on topic.

Mixing two PPM streams together to a TSLRS-compatible signal is pretty easy. It can be done via the buddy/trainer ports (or module port if you prefer).

One idea is to use a regular short-range radio module on one Tx, where the Rx connects to a Wizard. The Wizard also connects to the other Tx and TSLRS. The Wizard can mix up to eight servo channels together with the master PPM. Then you don't need to tie the two Tx'es together by a trainer cord.
Alas, I haven't tried this in practice.


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