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        Idea Channel Expander?

#1 JimDrew Jun 08, 2012 01:15 AM

Channel Expander?
 
With the 32 channel transmitter coming, we are having to look at ways to get all of these channels available. I had an idea today that I wish I would have thought of and implemented already.

What is everyone's thoughts on a channel expander for the XtremeLink system? This would be a very small board (not much larger than an end pin servo connector) that would have a single input and multiple channel outputs. Perhaps something like 10 channel outputs. I could change the Nano (and other receivers as well) firmware so that one of the channels was a 250Kbps (or more) serial datastream output that would be fed into the channel expander. It would delay the expanded channels by about 1ms. So, a Nano + 10 channel expander would give you 15 channels. These expanders could be very inexpensive, perhaps in $25 range. They would have auxillary power inputs for power hungry servos. You could use a Nano with a single servo extension located anywhere you like (as THE receiver, with no servos connected) and the expander being used for all of your servo (10) channels. The expander would have channel map programming, just like our receivers do.

We could make 10, 12, 16, etc. channel versions of these expanders. In theory you could have two 16 channel expanders and a single Nano to get 32 channels + 5 extra copies. This is somewhat like Futaba's S-bus, except the data speed would be much faster (less latency), and you can use the other channels on the receiver for servo... and there would be programming capabilities on the expander.

Comments?

#2 _Peter Jun 08, 2012 02:46 AM

Sounds like this will be a very neat setup........

#3 Swen Jun 09, 2012 12:17 AM

+1 This will then be the best setup in the world.

#4 JuanRodriguez Jun 09, 2012 05:35 AM

JD,

Sounds like a neat idea but with all due respect, I think that you should focus 100% of your efforts on getting the transmitter to market..... Make that 110% !! :)

#5 bruff Jun 09, 2012 04:47 PM

I could one for sure.
Bob

#6 tande Jun 09, 2012 05:59 PM

To a "layman" like myself....it sounds great!.....whats the downside?....(waiting?);)

#7 JimDrew Jun 09, 2012 11:15 PM

There is really nothing to develop with a product like this. The coding is already done (it's in the receiver). I am using the telemetry data stream for the data transfer (also already in the receiver), and the PCB artwork is almost completely done by virtue of having receivers already done. The only work really is to change the PCB artwork and test it. So, things like this do not take away any real time from transmitter project.

There are no downsides. You get more channels than current receivers, with the ability to locate the antenna away from potential interference (wires, metal parts, etc.)

#8 ChuckA Jun 10, 2012 08:18 AM

Quote:

Originally Posted by JimDrew;21836364 ?[/QUOTE
They would have auxillary power inputs for power hungry servos. You could use a Nano with a single servo extension located anywhere you like (as THE receiver, with no servos connected) and the expander being used for all of your servo (10) channels. The expander would have channel map programming, just like our receivers do. Comments?

I assume that the servo power on the expander could be totally independent of the Nano power. If so, then that would be a good reason to use the expander even if extra channels aren't needed.

#9 theKM Jun 10, 2012 09:47 PM

Quote:

Originally Posted by JimDrew (Post 21836364)
With the 32 channel transmitter coming, we are having to look at ways to get all of these channels available. I had an idea today that I wish I would have thought of and implemented already.

What is everyone's thoughts on a channel expander for the XtremeLink system? This would be a very small board (not much larger than an end pin servo connector) that would have a single input and multiple channel outputs. Perhaps something like 10 channel outputs. I could change the Nano (and other receivers as well) firmware so that one of the channels was a 250Kbps (or more) serial datastream output that would be fed into the channel expander. It would delay the expanded channels by about 1ms. So, a Nano + 10 channel expander would give you 15 channels. These expanders could be very inexpensive, perhaps in $25 range. They would have auxillary power inputs for power hungry servos. You could use a Nano with a single servo extension located anywhere you like (as THE receiver, with no servos connected) and the expander being used for all of your servo (10) channels. The expander would have channel map programming, just like our receivers do.

We could make 10, 12, 16, etc. channel versions of these expanders. In theory you could have two 16 channel expanders and a single Nano to get 32 channels + 5 extra copies. This is somewhat like Futaba's S-bus, except the data speed would be much faster (less latency), and you can use the other channels on the receiver for servo... and there would be programming capabilities on the expander.

Comments?

awesome! if you can also bake in the auto-matching for ganging servos, it would be rather epic :)

#10 theKM Jun 10, 2012 09:53 PM

Single servo wire from the expander to the Nano to power the Nano and get the signal to the expander is sweet... basically replicating my usual power harness setup without needing a dozen channel wires. IMO, if you can't reliably power the servos the plane is lost anyway...

#11 JimDrew Jun 10, 2012 11:57 PM

Yep, just like your setups, but with a single servo connection between the expander and the Nano. You can power the Nano and the expander electronics separately from the servo power, or from it.

#12 tande Jun 11, 2012 12:15 PM

OK, we're convinced!....Lets "Get'er/Done!....;)

#13 JimDrew Jun 11, 2012 12:17 PM

Samples are in route right now. I put two screw holes in the PCB so you can attach it like a power expander.

#14 bruff Jun 11, 2012 01:01 PM

I'm in!
Bob

#15 E_ferret Jun 11, 2012 06:07 PM

Quote:

Originally Posted by JimDrew (Post 21862033)
Yep, just like your setups, but with a single servo connection between the expander and the Nano. You can power the Nano and the expander electronics separately from the servo power, or from it.

add an optional opto-coupler connection and nobody will be able to blame noise from the digital servos to travel over the common ground wire to the rx.:cool:


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