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I would like to use the Raspi as a remote control for an RC receiver.

That means, I don't want to exchange the receiver and servo motor control with the Raspi, I would like to exchange the sender side.

So the Raspi sends signals to a Carson MR-8 8-Channel Receiver with 2,4 GHz, which is built in my RC model. MR8-Receiver Basically, this is a two-axis robot and an additional switch. However, those are in a different room so I would like to avoid using cables.

I am using mostly python, but I have been seen programming microcontrollers with C as well in the past, so I am not completely free of knowledge. However, the Raspi is new for me, it's here on my desk and I try to find out about it's capabilities.

Is that possible? Steering an RC receiver with 2.4GHz with the modules which are already onboard the Raspi? Or would I need some add-on module? I was looking into the NRF24L01 but not sure if this would solve the problem...

If this device uses Bluetooth, how would I find it with the PI?

Is it possible at all / are there vendor-specific codes which I wouldn't get?

Is there a module existing which shows how this kind of project is done?

Thanks a lot!

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    If you want some something specific for an answer, you'll have to provide a link to the specifications for the Carson MR-8. We have no idea what this is, or how it works.
    – Seamus
    Commented Mar 25, 2021 at 8:56
  • Searching since days for the electrical spec. It's a receiver with 8 PWM channel outputs... so far so normal. I was hoping that there is some standard protocol in the today's RC world that the PI could emulate for the communication. The manufacturer proposes to connect an Arduino or pi to the PWM outputs. :-) kondo-robot.com/faq/mr-8_board
    – Anderas
    Commented Mar 26, 2021 at 8:32
  • But if I do that on sender side, it would probably be easier and maybe even cheaper to use a Pi on sender side and another one on receiver side. Sad! That Carson receiver is nicely small, it'll never get that small with a Pi or Arduino.
    – Anderas
    Commented Mar 26, 2021 at 8:42
  • Could it be Bluetooth? How would I pair the PI with it then?
    – Anderas
    Commented Mar 26, 2021 at 9:46
  • Since the manufacturer doesn't supply the information online, and because I'm somewhat lazy, I would probably ask them what they use. The worst they can do is say no.
    – Seamus
    Commented Mar 27, 2021 at 5:55

2 Answers 2

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The Raspberry Pi wifi may use 2.4 GHz but wifi is unlikely to be the protocol used by your 8-channel receiver.

You need to find details of your receiver and then find a module which talks the same protocol.

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  • Thanks for that comment - I am almost sure that remote controls for playthings don't use Wifi right?
    – Anderas
    Commented Mar 24, 2021 at 15:08
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Ok, this is not easily doable. I will present you with the result of my little research into this topic here.

Every company has it's very own "secret" firmware and they are totally unwilling to share. There is probably no way of getting into the chain without serious hacking - simply using the Raspi or the NRF24L01 to get into the right frequency area is not going to work.

There are three ways of doing it now, some of which require some serious hardware hacking.

  1. Inject the Raspberry on sender side, emulate voltage levels on the output pins (with a PWM to Resistor-Condensator filter); give them to the sender and let the sender to it's normal work. Sounds kind of stupid to me, killing a perfectly fine sender like this and wasting a Raspi on top.

  2. There has been a hacker who was able to inject themselves into the protocol; again on hardware side. There is a microcontroller which communicates via SPI with the transceiver on both sides, so investing sufficient time one could put a FPGA as man-in-the-middle; it passes through most of the commands and injects it's own commands when you want it to. This has nothing to do with a little hobby project, though, and is definitely nothing for the Raspi.

  3. Using the Raspi as sender and a somewhat cheaper Arduino as receiver. I am looking into a D1 mini as receiver of wlan signals now. Wlan isn't perfect because there is a lot of signalling overhead and sources of delay - You normally don't want that when commanding a dumb & fast remote. Looking further, maybe my PC will be the sender and not the Raspi. Maybe this isn't a job for a Raspi, after all.

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