2 Replies Latest reply on Nov 20, 2014 9:52 AM by mifo

    Bulk Transfer throughput?

    user_305201620

      iDevices team,

       

      smonteith, daviddavis_1715526, ramaidevices, mikedaigle, michaeltetreault

       

      Can you comment on what the maximum throughput/transfer rate is using Bulk Transfer mode?

       

      Thank you,
      Andrew

        • 1. Re: Bulk Transfer throughput?
          smonteith1

          Depends on several factors.  First, if you’re talking to an iOS device, the connection interval defaults to 30ms.  Otherwise, if you’re running module to module, you should be able to bump it to 7.5ms conn interval and get 4x speedup.

           

          Also, it depends on the direction.  While 23 is the MTU, it’s subject to read/write operation semantics/protocol overhead.  Thus, for writes (from iOS to peripheral) you can only do 20 bytes.  However, for notifications (peripheral to iOS) it’s 22 bytes.

           

          The other caveat is that as of iOS7, Apple allows for larger MTUs, thus are not limited to 23 bytes, and can run it up to 256-512 or so.  However, Broadcom currently doesn’t support this.

           

          So, assuming a use case like OTA (iOS to Broadcom), you can theoretically run about 667 Bps (~5.3Kbps).  That’s 20 bytes every 30 ms.  If you’re Broadcom to Broadcom, you can do 20 bytes every 7.5ms, or ~21Kbps.

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          • 2. Re: Bulk Transfer throughput?
            mifo

            It should be noted that the device can send several (2073x by default is configured to 4) Write Commands, or Notifications, so this makes it by default 80kbps.

             

            smonteith user_305201620