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Adding an 8th channel to the P2?

Discussion in 'Phantom 2 Discussion' started by MikeSD, Feb 4, 2014.

  1. MikeSD

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    I'm wondering if this will work. I have the Futaba 14SG and it came with the R7008SB receiver.

    I know I can pair the 14SG to my stock receiver and have been using it that way. But I believe the stock receiver is limited to 7 channels. But it's S-Bus, so I don't know if that is strictly true. Is the stock receiver capability limited to 7 channels?

    So my next thought was to replace the receiver with the R7008SB. That has the ability to use 12 channels. The datasheet shows a mixture of conventional servos, sbus servos and s-bus2 servos. So this suggests what I want to do might be possible.

    I'd like to have
    1) Standard sbus channels 1-7, like the stock receiver.
    2) Two additional channels, using either the port connectors OR sbus channels OR sbus-2 channels, whichever is possible.

    My thought was to put the receiver in Mode D, and use channels 9-15 for some functions and sbus for the same functions as the stock receiver (1-7).

    My first question about the R7000SB datasheet is that it shows ch 1-7 and sbus for Mode B. Are the channel ports 1-7 controlled at the same time as sbus 1-7? Or, are they different?

    My second question is, if I put the receiver in Mode D, do I have sbus channels 1-7, like the stock Phantom 2, and channels 9-15, for other use? I was thinking it might be something like this:
    ch1: A
    ch2: E
    ch3: T
    ch4: R
    ch5: X1
    ch6: X2
    ch7: U
    ch9: Video switch
    ch10: shutter control

    Last question, for now, is if it's possible to use the R7008SB, to control the P2, just like the stock receiver, without making any other changes, other than replacing the receiver AND have some additional channels, what mode should I use?
     
  2. goldfishrock

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    To answer the last part of the post first I think you’ll want to put your receiver into Mode 2 (B). This should mean the SBus is controlling all of the ‘stick channels’. You’ll need to configure the switches you want to use for S1 & S2 and also which channel / know you want to use for the Gimbal tilt.

    Take a look at…. Although it’s for the older Phantom, you may need to tweak a few things however the majority of it applies.

    http://www.phantompilots.com/viewtopic.php?f=4&t=3931&hilit=Futaba+14sg#p27004

    I’ve recently installed a R2008SB Rx (using an 8J Tx) into a P2 and got it working well… I am just finishing off a guide to doing this which I will post shortly… you may find that most of it will apply to the 14SG too.
     
  3. MikeSD

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    The one thing I'm unsure about is this.

    If I configure for mode B, the datasheet seems to show the hardware ports, on the receiver, as ch1-7. And I know that the first 7 channels of sbus, are the stick and configuration of the stock receiver. But are the sbus channels (1-7) the same as the hardware ports that are also ch1-7. In other words, when I push the A stick forward, is the hardware port ch1 on the receiver also controlled, at the same time as the sbus ch1? OR are sbus ch1 and hardware ch1 different, from a control point of view.

    The fact you say use Mode B, seems to suggest I don't get the same sbus channels as I do, if I use Mode D.
     
  4. goldfishrock

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    My understanding is that the S.Bus channels are the same as the physical connectors on the Rx... it just makes those outputs redundant as the S.Bus output will override the physical output. It's just a simple way to elimimate physical connections.

    On the R7008SB to utilise additional channels outside of the allocated S.Bus channels I would suspect you place the receiver into Mode D. I think this way C1-8 (8 being the S.Bus channel) are dealt with over S.Bus and 9-14 possibly the physical outputs on the Rx (1-6)?

    Do you have a multimeter? You can always confirm this by seeing what happens if you are in Mode D, connect the multimeter to the V+ and Gnd pins (I think that V+ is the middle pin and Gnd is the bottom but you may want to check that) on one of the physical ports (1-4) and waggling the sticks. If you get nothing back then the above is correct. Alternatively if you have a servo, just plug it and and test.
     
  5. MikeSD

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    That's why I was thinking Mode D would be the way to go. But many people keep suggesting mode B. My list of channel assignments assumes I could use Mode D, for what I wanted.

    Testing: I have a plan for testing this, that doesn't require actually removing anything from my copter. I have some standard servos. I also have some S-Bus decoder adapter that has 3 servo outputs. I also have a sbus programming tool. I can set my decoder up for ch1, 2 and 3 and connect some servos to those 3 outputs. If I plug the decoder cable into the s-bus, that should simulate the first 3 channels that the Phantom 2 uses. And then select Mode D. If it's going to work, my 'A', 'E' and 'R' stick commands should control ch1, 2, and 3 servos (from the decoder) and if I program one of my transmitter (Futaba 14SG) switches to ch 9 and 10, I should be able to see control of those 2 channels. I should safely be able to assume (then) that ch 4-7 are also proper.