Reading asynchonously received packet on mDot (classC)

[Steeve Zissou]

Dear All,

I’d like my mDot to receive data from the gateway. I was able to do this with the function send() and recv(). Now I want to be able to receive data asynchronously, using classC capabilities.

I have studied the example “CLASS_C_EXAMPLE” from Multitech’s Dot-Example, but I can’t find a way to access the received packets’ payload.

Could someone show me a code to read the received packet (send by gateway to a classC configured mDot).

Thank you !

Steeve

[Jason Reiss]

Look at inc/RadioEvent.h in the Dot-Examples project.

[Momo Smith]

Hello guys,

I have seen the code in inc/RadioEvent.h.

I call RadioEvent(); just after the code to join a network.
In result, i don’t have a data in my console.

According to you, what is the problem ? or, what is missed in the main code CLASS_C_EXAMPLE for working correctly ?

Thank You.

• This reply was modified 7 years, 11 months ago by Momo Smith.
• This reply was modified 7 years, 11 months ago by Momo Smith.

[Mike Fiore]

Momo,

Your application should not be calling RadioEvent. It will be triggered by the Dot Library when events happen. If you set everything up, the Class C Example from Dot-Examples should work.

https://developer.mbed.org/teams/MultiTech/code/Dot-Examples/

There needs to be something on the gateway side that is actually sending data to your device. We have some examples of how to do this on our developer site.

Conduit mPower: LoRa Communication and Node-RED

Conduit mLinux: LoRa Communication

Cheers,
Mike

[Momo Smith]

Hi Mike, thanks for your response.

On my conduit, i created a inject button, a fonction and a output Lora.
In my fonction, i use eui node and payload “hello”.
On my node i use the class_c_exemple.cpp. I can see the message payload on the console (putty), but why need to send a dummy message before to receive my payload ?
I thought the node was always in receive when it is in class_C. Maybe i am wrong ?

If i comment the code ( class_c_exemple.cpp) between “#if defined(TARGET_XDOT_L151CC)” and “endif”, i can’t receive my payload. Why ?

[Mike Fiore]

Momo,

Did you update the node to class C on your network server after it joined? You need to use lora-query to do this. That step is documented in the Class C example program.

Your node is in class C mode, but the network server needs to be informed of this and there is currently no LoRa message in the standard for that purpose. It must be an Out Of Band (OOB) message at this point.

Cheers,
Mike

[Momo Smith]

To response at the last message Mike,
Your information is correct. My server isn’t in class C. I modify my configuration.
Thanks.

So I have a other question.
I wish used one node in class_A to send a message for my server and an other node in class_c to receive this message from server.

Mike, you think what this configuration is possible ?

Thank you for your time and involvement.

[Mike Fiore]

Your application would need to handle that scenario. There is no support in the Network Server for routing messages between nodes.

Cheers,
Mike

[Momo Smith]

Hi Mike,
I have configure my server today.
My program working now. Thank you.

[Momo Smith]

Hello friends,

Now, my node is in class C. I can see each data in a console. I would like to retreive data for send it with a UART connexion. I read a differents functions in file mDot.h. There is just one function to receive named recv(). In comment, it’s note “send() must be called before recv()”
So, my question is :
What is the good fonction i need to use for receive each datas in real time without use send() before ?

Thank

[Jason Reiss]

You will want to accept the received packets in the event handler

examples/inc/RadioEvent.h

Add your code to the MacEvent function.

RadioEvent::MacEvent(LoRaMacEventFlags* flags, LoRaMacEventInfo* info);

if (flags->Bits.Rx) {           
      logDebug("Rx %d bytes", info->RxBufferSize);
      if (info->RxBufferSize > 0) {
          // print RX data as hexadecimal
          //printf("Rx data: %s\r\n", mts::Text::bin2hexString(info->RxBuffer, info->RxBufferSize).c_str());
 
          // print RX data as string
          std::string rx((const char*)info->RxBuffer, info->RxBufferSize);
          printf("Rx data: %s\r\n", rx.c_str());

          // TODO: output to UART
      }
}

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