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MSPF5438A + CC2564QFN changing the MTU in L2CAP

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Replies: 6

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HI,

I want to transmit around 2000 bytes in order to check the maximum throughput that this board will allow to trasmit but in order to do so I have to send data that is big enough to fill the whole frame in Bluetooth. I am using a simple application in Java which allows me to transmit sample message to the board and back, then I measure the duration of the process and I have the maximum throughput that can be achieved. On the board side I am using Spp demo, how can I change the MTU value in L2CAP so I can send bigger size data at once?

thanks for  your help

  • Hi Robert,

    I have moved this to the Bluetooth® forum because it seemed to be about the Bluetooth software rather than the MSP430 device itself. They should be able to better help you there.

    Regards,
    Katie
  • Hi Robert,

    Are you familiar with this wiki page? : processors.wiki.ti.com/.../CC256x_MSP430_TI's_Bluetooth_Stack_Basic_SPPDemo_APP_Improving_throughput_v14

    You can change the size of the TX Buffer, RX Buffer etc. for the SPPDemo like explained in this wiki page. This can help do the quick modifications for throughput tests.

    Moreover, you will find 2 folders in the MSP430_Experimentor/Bluetopia/Lib/<IDE> named DefaultMTU and LargeMTU. The DefaultMTU has the core libraries compiled with L2CAP MTU = 335 bytes and these libraries are linked to all the demo examples by default. You can link the core libraries from the LargeMTU folder instead. These libraries were compiled with L2CAP MTU = 800 bytes. Please refer to the Release Notes included in the CC256XMSPBTBLESW for details.

    Best regards,
    Vihang
  • In reply to Vihang Parmar:

    Hi, Thanks for help, do you know have to change links this folder to larger MTU? Because I cannot find anything in the link you provided.

  • In reply to Robert Kopaczel:

    Hi,

    Ok so I found a way to use "larger MTU", but it didnt change a thing when tallking about throughput!

    So thanks to "larger MTU" I can now set first parameter of config params to 800 instead of 335 but it doesnt change a thing!

    I have a simple java programme that lets me send a fixed number of bytes to microcontroller which sends it back immediately with loopback mode.

    And whever I send a message it devides is into 256byte messages and this is why I think the throughput is so little. 

    I measure the time of the transmittion and that's how my throughput is about 170kb/s instead of couple mb/s like it is written in datasheet!

    Can someone explain it to me why I can send max. 256bytes at once despite the fact that my config params are 800 987 2303, baudrate 921600 and uart buffer sizes 1042, 384 plss?

  • In reply to Robert Kopaczel:

    I still havent found the answer so Im refreshing the topic

  • In reply to Robert Kopaczel:

    hi , pls open a new thread for different query
    Saurabh

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