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DirectIO Edma streaming example

smeil smaili
Intellectual 325 points

Hello,

I'm executing the edma rapidio streaming example provided by the DIO library 1.0 on the evm board (c6474) and i want to modify/know the used data rate (3.125 ; 2.5 ; 1.25 gbps)

I guess that could be changed from these 2 lines of code of the example :

#define     PLLC_PREDIV_CLK    1        // PLLC_PREDIV_CLK - 1 set to register             
#define     PLLC_PLLM_CLK      20       // PLLC_PLLM_CLK - 1 set to register     

What does 20 mean ? I want to set it to the full value (3.125) .. according to the user guide, an MPY value of 12.5 must be used !

I've another question about time mesurement using the 2 DIO functions :

    t1 = COM_startChrono();
    t2 = COM_stopChrono();

How to get the value of spent time (in ns) from t1 & t2 and how to know the DSP working frequency ?

By the way, what does that structure field mean in the example : testObjTab[k].raw_lsu_setup=1; ?

Thanks !

  • 0
    Expert 1070 points

    In cslUtils.c\DIO_portSetup() find:

     

            hSrio->portPllMpy[0]   = CSL_SRIO_SERDES_PLL_MPLY_BY_12_5;

            hSrio->portRate[0]     = CSL_SRIO_SERDES_RATE_FULL;

     

    This sets the speed for port 0. Use the table below to change to a different rate:

        {CSL_SRIO_SERDES_RATE_HALF,     CSL_SRIO_SERDES_PLL_MPLY_BY_10},    //1.25Gbps

        {CSL_SRIO_SERDES_RATE_FULL,     CSL_SRIO_SERDES_PLL_MPLY_BY_10},    //2.5Gbps

        {CSL_SRIO_SERDES_RATE_FULL,     CSL_SRIO_SERDES_PLL_MPLY_BY_12_5}   //3.125Gbps

     

    The trick is that you have to change both.

     

    The chrono functions return clock cycles if i am not mistaken. You get the nr of ns via you core clock frequency.

     

    HTH,

    -Dirk