Broadcast in BLE LLD

[Marcelo Barros]

Hello

Analyzing the source code of some BLE LLD examples for nucleo stm32wb55 I could see that broadcast is used in Proximity example and unicast in Chat example, for instance. However, I could not understand how to choose between unicast or broadcast. Only calling an LLD function without ack will do this or there are some special addresses for broadcast ? Is there any additional documentation about BLE LLD besides UM2804 document ?

Thanks a lot.

[lecozj]

Hello Marcelo,

In proximity a transmission is done without acknowledge reception expected. In chat a transmission is done with acknowledge reception expected. Example Applications are present to also demonstrate several cases. Every board using BLE LLD is able to receive or transmit any kind of BLE format packet but without using BLE protocol. just need to manage NETWORK ID, channel and rate and encryption is you want.

This is your application requirements that specify if you need an ack or not. You can also modify Chat Example without ack by selecting different LLD function making it as you mention "broadcast". But there are no such BLE notions with BLE LLD, there is no broadcast or unicast, GAP or GATT concepts. There is no special addresses for broadcast or unicast then, it simply allow to send or received packets. All addresses can be used.

Beside the UM2804 there is not additional documentation.

Regards,

Julien