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Original question:

CC2640R2F: BLE5.0 star network

CC2640R2F: BLE5.0 star network

Mircea Iuonas
Intellectual 545 points
Part Number: CC2640R2F
Other Parts Discussed in Thread: CC2530

Hello,

I have a question similar to the linked post, but somehow different. I would like to make a star topology with multiple nodes (maximum 100), all of them sending data, for a short period of time, to a Master. The current solution we have is based on CC2530 and works fine but we would like to use the Bluetooth 5 protocol for efficiency. For the CC2530 project we developed a custom protocol, which would like to avoid (if possible) due to resource consumption and time to market.

Each node will stay in sleep for most of the time and will send the data every now and then (raging once every few seconds to minutes). Also we need an acknowledge based system, bi-directional, where messages are not lost and if/when that happens, the slave or master could ask for the same message again.

Mesh solution is not the best since all the devices (except the master) will be placed in an extreme environment and the Master will be placed in another environment, so most of the times the Master will have the worst link compared with the other nodes, but that is the final destination of the package.

Thank you. 

  • 0
    TI__Mastermind 34660 points
    Hello. In BLE you have two methods of sending data:
    - advertising / scanning (this is a broadcast)
    - forming a connection

    It sounds like you can't just broadcast data since you need an acknowledge based system.

    That means you must form a connection. As YiKai stated in the linked post, the maximum amount of simultaneous connection supported on this device / software is 8 due to RAM limitations. So in order to have a star network of 100 devices, you will need some scheme to continuously disconnect and reconnect devices.
  • 0 in reply to Tim C
    Intellectual 545 points

    Hello,

    Do you have any idea how long the connecting/disconnecting takes? Is it timing feasible? 

    Thank you for the support.

  • 0 in reply to Mircea Iuonas
    TI__Mastermind 34660 points
    It is not deterministic as it depends on both environment RF factors as well as semi-randomness of the slave's advertisements aligning with the master's scan attempts to connect. Beyond that, it depends on other factors such as how many connections the master currently has as well as the connection interval of each connection and how much throughput is occurring during scanning.

    To give you an idea of a simple environment, where a master is connected to a slave at the fastest connection interval (7.5 ms), it should be able to disconnect and reconnect to this same slave (or another slave) in 20 - 30 ms.
  • 0 in reply to Tim C
    Intellectual 545 points

    I understand. Thank you very much for the useful information.

    Have a great day,

    Mircea