Lora remote control

Projects General Guidance
1

We have a project that i think Lora would be suitable for. Sorry about the long winded description

I want a simple remote control system to turn on some relays. The system will be used with a transmit distance of up to 200m in steep rocky terrain and forest, with no line of sight.

The system will consist of 3 handheld transmitters, and 2 receivers (would be great if I only needed 1 receiver, but as far as i can tell, I will need 2)

Let's call the transmitters T1, T2 and T3, and the receivers R1 and R2.

When a button is pressed on T1, R1 will turn on relay 1. Once the button is released, the relay will turn off

When a button is pressed on T2, R2 will turn on relay 2. Once the button is released, the relay will turn off

When a button is pressed on T3, R1 will turn on relay 3. The relay will stay on until the button is pressed again.

T1 and T2 need to be able to transmit simultaneously without interfering with each other.

T3 will only ever be used by itself.

I would like to have a delay of 0.5s or less from when the button is pressed, to when the relay turns on or off, but 1s would be acceptable if necessary.

I was thinking that if I run T1 and T2 with different spreading factors, then that should stop interference.

Am I likely to need an external antenna to get the range I am chasing, or will a board mounted pig tail antenna suffice?

There seems to be a lot of different libraries to implement lora. Which one would be best suited to this project?

Also, would an arduino be the best board to use, or is there a better alternative?

Thanks

2

You might be better off with low cost 433MHz long range key fob transmitters. and appropriate receiver.

They’re cheap, easy to integrate, and you don’t have any significant data payload.

Also, because you want the transmitters to cooperate, separate receivers $10 each would be simple.

3

Hi,
Is there a reason for 3 separate Tx and 3 separate Rx?

One TX and one Rx can do that job.

Thanks.. Tom.... :grinning: :+1: :coffee: :australia:

4

Tx will be used by separate people, to control different parts on machine, so I need 3 separate remotes, with 1 button each, to avoid confusion.

5

Do you have a link to one?

6

Goo.gl worked for me…
https://www.google.com/search?q=hobby+keyfob+transmitters+arduino&rlz=1C9BKJA_enAU768AU768&oq=hobby+keyfob+transmitters+arduino&aqs=chrome..69i57.14841j0j7&hl=en-GB&sourceid=chrome-mobile&ie=UTF-8

Are there any hazards working the equipment?

You may want think hard, and plan even harder for interlocks and fail-safe operation.

7

Nothing on that search really looked like it would be capable of > 200m operation without LOS.
The relays wind up a hose reel. It will be setup so that if it doesn't receive correct info from transmitter, relay will switch off

8

There are worked examples of using LoRa devices, both UHF and 2.4Ghs ones, to remotely control outputs on a reciever here;

Look in the \examples\SX127X_examples\Reliable folder.

The transmitter sends a packet built like this;

struct controllerStructure
{
  uint16_t destinationNode;
  uint8_t outputNumber;
  uint8_t onoroff;
}__attribute__((packed, aligned(1)));           //remove structure padding so there is compatibility between 8bit and 32bit Arduinos

Where 'destinationNode' allows a particular receiver to respond.

Examples using writes to an array or direct to the SX127X internal buffer.

Also examples where the transmitter keeps sending until it gets an acknowledge etc.

9

Thanks.

I will work my way through those examples