Pixhawk 2.4.8 ELRS transmitter and receiver and telemetry

Hello all , I am new to the RC drones hobby and all ,
I am planning to make a drone and have Pixhawk 2.4.8 version ,
now I am planning to buy RC transmitter with ELRS and have decided to use TX12 Mark II Radio Controller (with ELRS, Mode 2 , FCC region), what I didn’t know then was , I won’t be getting a receiver along with the transmitter . Please suggest me some receiver , and also could you guys suggest me some telemetry and do I actually require it ?
and just to clarify this isn’t an FPV drone
Pixhawk Telemetry (Comms) :satellite: Uncategorized #ELRS Hardware / Pixhawk Coordination

You don’t need telemetry if you are happy “flying blind”
In fact some of us started out that way and decided to add telemetry at a later stage.
With telemetry:

  • You can see live data on the groundcontrol-station, this is handy as you will see all sort of things like how high you are actually flying (many countries have legal limits in regards to height). Speed, direction, battery voltage, electrical current,…and many more things.
  • You can also apply certain commands directly and drone will respond accordingly.
  • When flying way-point missions you can see its progress and if it stays on track.

The important thing is the safety aspect:

  • Without it, how will you know when your battery is getting low?
  • How will you know if there is a problem with a sensor?
  • You won’t receive any warning messages - (Both are available in writing and spoken if connected via telemetry)
  • How would you know drone is flying beyond fence (artificial area which can be setup to keep drone within a specified area)

Thanks for the info @Karl_Schoelpple , Can you suggest me some telemetry for my build .
Ready to Sky Q450 Quadcopter Frame – PCB Version Frame Kit with Integrated PCB is my frame ,
2212 920KV Brushless DC Motor for DJI Silver Cap (CCW Motor Rotation)and
DJI 2212 920KV Brushless DC Motor for Drone with Black Cap (CW Motor Rotation) are my motors
SimonK 30A BLDC ESC Electronic Speed Controller with Connectors are the ESC’s I am using.

As mentioned earlier could you suggest me a good receiver for the above Radio Controller.

And just for sake of clarity , ELRS is supported by Pixhawk 2.4.8 and Mission Planner 1.3.80 and firmware Copter V4.4.1 OFFICIAL, right? or would I have to buy anything more than the receiver for it to be connected and interfaced.

OK. As you’ve mentioned Ardupilot you should ask those questions on their forum:

In regards to telemetry there are various options from a low cost set of telemetry radio with a range of around 100m to a WiFi system (range 40m) to a system using 3G/4G which is able to operate anywhere in the world where mobile phone reception is available.
Besides range, there is also the consideration of just using telemetry or perhaps later using live camera footage. In that case you need a system which can deal with such large amount of data. (WiFi & 4G can, some others can’t)

Also in regards to this you will get lots of info on the Arducopter forum.

In regards to ELRS see here:

Thank you @Karl_Schoelpple , so could you suggest me a good receiver for the RC I am trying to use,

Yeah , I will ask there , thanks :smiling_face:

There are many receivers available for your transmitter.

One suitable example:

But as mentioned many to choose from:

Once you have the receiver just bind it and connect to FC. Start radio-calibration and other sensor calibration.
You can use Mission Planner or GroundControl for that. - I suggest download both and play around with them to see which works best for you.

Since you most likely will have to use Arducopter for your setup here is info on how to get started:

Thanks for the info , I am trying to find out the difference between all the different kinds of receivers over there .
I am unable to figure out what is needed for my quadcopter and also what is the difference between RP1 ,RP2,RP3 ELRS Nano Receivers and ER4 ER6 ER8 2.4GHz ELRS PWM receivers?

- - - - - - - -
Also do I only have to buy the receiver or any other extra hardware with it ?

Those are basic RC-Hobby related questions and can be answered by those forums.
Some quick info: The number behind the model type is the amount of channels it has. I.e. ER6 means it has 6 channels available. = You can connect up to 6 devices (servos,motors,aux-switches,…)

The Letters in there refer to the design of the receiver. As seen in the photos of the radiomaster website. Those with “ER” are regular fully enclosed receivers. = Just plug your servos, motors and other equipment in.
The "RP’ series appears to be a bare bone design to save weight and reduce size. But this also means you have to solder everything onto it and perhaps make your own casing or find other ways to protect the circuit board. = More specialized product to suit very specific applications.

Since you have bought a 12 channel transmitter wouldn’t make much sense just buying a 4 channel receiver.
→ 4 channels is the minimum you’ll need to fly a drone. (throttle, yaw, pitch, roll)

Given that most people will add a camera, aux-switch, gimbal or any other additional equipment, it makes sense to have a few channels to spare on your receiver. (The only time you want just the bare minimum is if you intend to use a very small, lightweight drone and can afford the extra space & weight)

2.4GHz is the frequency it operates on.

ELRS is the type of signal it uses. (Think about it like a specific language)

Thank you so much @Karl_Schoelpple , now it kinda makes a lot of sense to me . And as you have mentioned, about the channels in the receiver, could you please point me towards the one compatible with my RC, by compatible I mean the one that has all 12 channels on it … that would help me a lot.and is there any way I would be able to know how many channels a RP receiver has ?

I was also thinking to buy RP3 ELRS Nano Receiver. (Does my decision make sense? Or is it terrible :smiling_face_with_tear:?)

Your consideration for the RP3 ELRS Nano receiver makes no sense. It is exactly the type you have to solder wires to it and also find a way to protect it with casing or at least shrink wrap.

This one allows you to simply plug in devices without soldering and without having to find a solution in regards to casing.

As the number “8” suggests, it is a 8 channel receiver allowing up to 8 components to be connected. That brand hasn’t got any 12 channel receivers and you will find it hard to find any, as some of the other channels are used for additional functions like flight mode switching, landing gear activation, motor safety cut-off,…)

Thank you for suggesting me a simpler one,

I don’t think that would actually be a problem to me.
And secondly based on my understanding those PWM receivers are basically used for boats, fixed wing aircrafts and such(atleast that’s what I understood from all the comments on them).

Apart from the soldering and plug and play , are there any issues I might face with the choice I made ?.(I mean any compability issues with pixhawk2.4.8 or any other technical snag that I might have never came accross as of now).

Thanks a lot for this info, I didn’t actually know this ,and also is there any way to tell the number of channels for RP series too,or atleast for the RP3 ELRS Nano Receiver?

I in particular liked the diversity antenna receiver :slightly_smiling_face:

The RP3 passes all the channels from your transmitter to the FC. - But no way to connect any devices (servos,ESC’s,…) driectly.
Out of the 3 Nano receivers the RP3 is the best one with better range and two antennas.

I believe your other questions have been answered in your other post on the Ardupilot forum.

Good luck, happy & safe drone flying.

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(this is my first post to discuss.px4.io… ) I have a simple question possibly related to this discussion.

How do I to connect a RadioMaster 2.4GHz RP1 ELRS FPV receiver (RP1 V2 ExpressLRS 2.4ghz Nano Receiver – RadioMaster RC) to Pixhawk 6c?

RP1 has 4 pads (5v, GND, TX, RX).
(1) Can I connect those pads to the Pixhawk 6c TELEM2 (Pixhawk 6C Ports | Holybro Docs) VCC, TX(in), RX(in), and GND.
(2) Does RP1_TX connect to 6c_RX(in)?

I have scoured the internet for this basic info, and could not find anything. Am I missing something basic here? Thanks to anyone who can tell me what to do before I try the wrong thing.