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BLE mesh CC2541

INg
Genius 3475 points

Other Parts Discussed in Thread: CC2541

Hi

I have a couple of questions on BLE:

1) For the BLE using CC2541 is it possible to connect up as a mesh? If not, I believe star is possible, yes? Is there any max number of nodes in a star or mesh configuration?

2) For BLE, our undersatndning is there are 49 channels used, 3 for advertising and after which there would be a hop to a not busy channel. However, when using two EVB, first board establish communication and continuous transmission. When we get the second board to establish communication, it goes to the same channel as the firs board, instead of the other free 36 channels. Is this a fair observation.

Ivan

  • 0
    Guru 735695 points

    1. It only supports star network. Currently, the BLE central stack supports up to three simultaneous connections according to page 12 in TI_BLE_Software_Developer's_Guide.pdf.

    2. Yes, it is a fair observation.

  • 0 in reply to YiKai Chen
    Genius 3475 points

    Hi YiKai

    1. Noted

    2. Do you expect all the subsequently pairing to use the same channels (even when these channel are beening used)? I read that BLE is suppose to hop, correct?

     

    Ivan

  • 0
    Guru 22270 points

    Hello Ivan,

    1.  The BLE Architecture is a Client/Server one.  There can be only one Master.  The TI BLE Stack limits the number of Slaves to 3.  It is a Star topology (Piconet) where a slave can have only one connection.  It does support Advertisers and Scanners which does increase the number devices in the configuration, however, the Advertisers cannot form a connection with Slaves.

    2. I am only aware of 37 Piconet channels being supported (0-36) in the Physical Layer and yes, 3 are used for advertising (37-39).  For the BLE, each slave has to communicate on a separate channel.  When the second board is establishing a connection, it would use the same 3 advertising channels, but once a connection is established, it would have to be on a separate channel.

    You can download the Core V4.0 Bluetooth Specifications from www.bluetooth.org.  All the details are outlined in a fairly straight forward manner.

    Thanks,

  • 0 in reply to Greenja
    Prodigy 10 points

    Hum, CSR announced the BLE Mesh technology, how about TI?

    http://www.csr.com/news/pr/2014/csr-mesh

  • 0 in reply to Patrick Liang
    Guru 735695 points

    TI employee won't reveal roadmap in this public forum. I would suggest you to contact local TI representative for these information.

  • 0 in reply to Patrick Liang
    Guru 22270 points

    Hello Mr. Laing,

    You managed to awaken me from my slumber!  It looks like the SIG Bluetooth has been listening to people's request and complaints.  The variable timeout interval will definitely solve a lot of issues In the new BLE v4.1.

    Now about this mesh network stuff...  

    It opens up a whole new dimension to BLE with the ability to act as hub and endpoint simultaneously.  This is what I have been waiting for.  I have just downloaded the Core_v4.1  and will have to see what the exact specs are.  https://www.bluetooth.org/DocMan/handlers/DownloadDoc.ashx?doc_id=282159

    It has been a while since I looked at the BLE firmware versions from TI, but I am sure the team in Oslo are about to come up with a new release sometime soon!

    Thanks for bringing this up!

  • 0 in reply to Greenja
    Prodigy 10 points

    I do have a client with 70 ha of green houses. He want to measure the humidity and temperate in those greenhouses.

    It would require several hundtred sensors. They should be solar cell operated (install and forget) and should

    for a mesh network to send their data to the central measurement server.

    yours 

  • 0 in reply to Edmund Humenberger
    Guru 735695 points

    Hi Edmund,

    I would suggest you to use Zigbee for your client's application since Zigbee is designed for mesh network.