There are differents things you need to do or check to use multicast :
First, you must know the multicast is not implemented in class B on our devices, it’s supported only in class C.
On the device side, you must use the Remote Multicast package that is use when you want to enable a FUOTA session (LmhpRemoteMcastSetup.c).
You have to enable this package by calling the function LmHandlerPackageRegister (PACKAGE_ID_REMOTE_MCAST_SETUP, NULL) define in LmhpPackagesRegistration.c.
This will allow the device to support LoRa MAC commands related to multicast.
On the server side, you must ensure the Application Server you are working with use the same protocol as the one implemented in the device.
When we develop our code, we use the technical specification TS005 1.0.0 as reference, so if the server Loriot, or TTN, or Actility… do not use the same protocol with the same commands you could not establish a multicast session (check the spec of each server to know which one is supported).
Also, you can create your server and if you follow the TS005, create the MAC commands the server need to send to the devices to match with the ones describes in TS005, and enable a multicast session.
For more information, you can refer to this Application Note : AN5554 LoRaWAN® firmware update over the air with STM32CubeWL: https://www.st.com/resource/en/application_note/an5554-lorawan-firmware-update-over-the-air-with-stm32cubewl-stmicroelectronics.pdf
Section 2.4.4
Regards
Hi @LAUDO
I have followed your advice, thanks again by the way.
I have added needed packages (especially LmhpRemoteMcastSetup) to enable a successful multicast session in the LoRaWAN_End_Node project. Now, my STM32WL seems to be ready for multicast.
Indeed, according to the instructions given into the LoRaWAN Remote Multicast Setup Specification v1.0.0 (https://lora-alliance.org/wp-content/uploads/2020/11/remote_multicast_setup_v1.0.0.pdf), I have successfully sent Multicast commands on port 200 to the device and it has responded with the expected answers. I have tested McGroupSetupReq/Ans, McGroupStatusReq/Ans and McClassCSessionReq/Ans.
To be noted, I have also tested time synchronization commands on port 202 (such as PackageVersionReq, DeviceAppTimePeriodicityReq, ForceDeviceResyncReq) thanks to LoRaWAN Application Layer Clock Synchronization Specification v1.0.0 (https://lora-alliance.org/wp-content/uploads/2020/11/application_layer_clock_synchronization_v1.0.0.pdf). It also worked well.
However, I did not achieve my goal: make multicast session work. As a first step, I would like to toggle a LED on 2 STM32WL simultaneously.
Here are the issues I meet:
When I have done my multicast command test, I have scheduled downlinks on a TTN application. And one of the fields of the McGroupSetupReq is the McKey_encrypted. Since I have neither the McKey nor the tool to encrypt it (to have the McKey_encrypted), I have randomly generated a McKey_encrypted.
The questions are:
1) Where, in the LoRaWAN_End_Node project, should I set the GenAppKey?
2) On the server side, I need the McAddr, the McAppsSkKey and the McNetSKey to create a Multicast profile. I can randomly generate the McAddr and then set it in the device thanks to McGroupSetupReq command. However, it remains McAppsSkKey and the McNetSKey. How should I proceed to have these elements? Of course, I need the same values both on the server side and on the device side.
Really appreciate your attention, thank you!
Regards,
To be noted: I would also precise the devices I work with:
- a STM32WL55 as device
- P-NUCLEO-LRWAN2 Gateway
- Actility or TTN as NS
