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SimpliciTI MSP430FG4618 Experimenters Board

Mike2108
Intellectual 460 points
Other Parts Discussed in Thread: SIMPLICITI

I'm trying to send a message containing four bytes from the MSP-EXP430FG4618 experimenters board within a short time frame.

Using an 8 MHz clock, would anybody know the minimum possible time requirement for sending a message of a similar size to this?

Using a timer, it appears to be taking 2.42 ms, or 17958 clock cycles,  just to send the message sucessfully.

Does this seem like a realistic time for a frequecny of 8 MHz, and if so, is there any way to reduce it, besides reducing the message size?

 

The code is included below.

The time was taken just for this statement:-

 SMPL_Send(linkID1, msg, sizeof(msg));

 

  • 0
    TI__Mastermind 21125 points

    Hi Mike,

    SMPL_Send consists of actual radio transmission and this function will not return until one has succesfully sent the data.
    How long this takes depends on:
    - RF Datarate (by default set to 250 kbps)
    - Radio overhead (actual transmitted data is more than just sizeof(msg) - see simpliciTI documentation to get the full overview)
    - Radio calibration and switch states
    - Network overhead / processing time (time from SMPL_Send is called until MRFI_Transmit and the actual transmission starts etc)
    - Radio interference (SMPL_Send consist of a method for checking if the RF channel is free before transmitting, this takes time and if it fails it will retry a given number of times)

    There are things one can do to speed up this and I posted some ideas here:
    http://community.ti.com/forums/p/2127/8002.aspx#8002

    Regards,
    Kjetil

  • 0 in reply to Kjetil
    Intellectual 460 points

    Hi Kjetil,

    Thanks very much for the reply.

    I'm having some trouble change the transmission type to forced.

    I know that the command is evaluated in mfri_radio.c using the line:-

     if (txType == MRFI_TX_TYPE_FORCED)

    but I can't seem to find where to set the parameter txType.

    Could you let me know where this is set, or how to specify the tranmission type?

    Thanks again,

    Mike

    -edit-

    I was able to change it, so thats fine now.

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