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MTU size in BTool

Jan Hakl
Prodigy 170 points

Other Parts Discussed in Thread: CC2540, CC2640

Hello, 

I'm using CC2540 with BTool as central device to communicate with peripheral device. This peripheral device send data with MTU size 26. The problem is how to change MTU size in BTool, I tried to change it by instruction GATT_ExchangeMTU and I have successful response. But I am still not able to receive longer message prom Peripheral device. I tried  to communicate with this peripheral device using the application in my cell phone, there it works. Is there something else what I have to set in BTool?

Thanks  

  • 0
    TI__Mastermind 23440 points
    Hi,

    The CC2540 is not able to use higher ATT MTU sizes than the default 23 bytes at this time (BLE SDK 1.4.1), unfortunately.

    Best regards,
    Aslak
  • 0 in reply to Aslak N.
    Prodigy 170 points
    Is there any way how to change it in the IAR project?
  • 0 in reply to Jan Hakl
    TI__Mastermind 23440 points
    No, unfortunately. The MTU size increase above 23 is based on fragmentation of longer higher layer frames into several fixed size LL frames, and recombination of LL frames into possibly longer higher layer frames. This is not implemented in the stack for CC254x.
  • 0 in reply to Jan Hakl
    TI__Guru** 105180 points
    Hello,

    If a larger MTU size is required, I suggest using CC2640 which can support a max 251 byte ATT_MTU.
    You can use the HostTest firmware on a CC2650DK to connection with BTool.

    Best wishes
  • 0 in reply to JXS
    Prodigy 170 points

    I'm using the CC2540 in USB dongle. I didnt found the dongle with CC2640, only evaluation board. Is it possible to connect the evaluation board for CC2640 over USB, and use it the same way as CC2540? 

    Thanks

  • 0 in reply to Jan Hakl
    TI__Mastermind 23440 points
    Hi Jan,

    Yes, both the SmartRF06 board with eval module and SensorTag + XDS110 debugger devpack can be connected to as USB com ports from BTool when the HostTestApp firmware is loaded.

    Best regards,
    Aslak
  • 0 in reply to Aslak N.
    Expert 1090 points

    Hi ,

    HW used : SmartRF06 board with eval module

    Sw Used for Eval Module: host_test App provided by TI of V2.2.1 Modifying MTU size from 23 to 60 Bytes in ble_user_config.h file.

    Expecting : By using BTool I should be able to read long characteristic which is having 40 bytes.

    Result :
    [110] : <Error> - 10:56:15.522
    Command Failed
    Status = Timed Out Performing Function
    Event = GAP_HCI_ExtentionCommandStatus

    Did I missed changing anything in host_test App or what could be the problem. Did any one faced this issue.

    One more information is if I am trying to read the characteristic which is having less than 23 bytes then I am able to read the data without any problem.

    Thanks for your response in advance.

    Thanks,
    Siva.