ADC total converting time

Hi Phien,

What ADC clock value are you using?

Regards,

Gautam

Hi Gautam,

I use 150MHz,  ADC module configuration as: 12.5MHz and S/H is 3.

Thank you,

Phien

I use 150MHz,  ADC module configuration as: 12.5MHz and S/H is 3.

Then ADC clock is pretty fast! Also, instead of using timers try with toggling GPIOs before and after conversions. There's one more alternate; you can use Clock profiler for check the conversion time.

Regards,

Gautam

Hi Gautam, 

I try with ADC clock is 6.25MHz and S/H is 16, value in timer counter is the same. And if i increase '65' to '70' or more, my program can not return main because time need run program in timer more than 250us. I don't understand with  a very fast ADC module why it needs very long time to read ADC.

Best regards,

Phien

I don't understand with  a very fast ADC module why it needs very long time to read ADC.

Phien, did you confirm the same using Clock profiler?  250us is very very high!

Hi Gautam,

This is my code config for timer0:

void ConfigCpuTimer(struct CPUTIMER_VARS *Timer, float Freq, float Period)
{
    Uint32  temp;

    // Initialize timer period:
    Timer->CPUFreqInMHz = Freq;
    Timer->PeriodInUSec = Period;
    temp = (long) (Freq * Period);
    Timer->RegsAddr->PRD.all = temp;

    // Set pre-scale counter to divide by 1 (SYSCLKOUT):
    Timer->RegsAddr->TPR.all  = 0;
    Timer->RegsAddr->TPRH.all  = 0;

    // Initialize timer control register:
    Timer->RegsAddr->TCR.bit.TSS = 1;      // 1 = Stop timer, 0 = Start/Restart Timer
    Timer->RegsAddr->TCR.bit.TRB = 1;      // 1 = reload timer
    Timer->RegsAddr->TCR.bit.SOFT = 1;
    Timer->RegsAddr->TCR.bit.FREE = 1;     // Timer Free Run
    Timer->RegsAddr->TCR.bit.TIE = 1;      // 0 = Disable/ 1 = Enable Timer Interrupt

    // Reset interrupt counter:
    Timer->InterruptCount = 0;
}

// This is code config for timer in main.c
ConfigCpuTimer(&CpuTimer0, 150, 250);

And code select clock for chip i used as example in control suite only change target is F28335.

Please help me.

That's fine Phien! I want you to check with clock profiler. Check this link:

http://processors.wiki.ti.com/index.php/Profile_clock_in_CCS

Regards,

Gautam

Thank you very much Gautam, 

I will check it.

No problem. Do let me know!

Hi Gautam,

I checked it with clock profiler and this is result:

When I use number of ADC sample is 1 in for function: it's 865, when number of sample is 10: it's 11677.

And here is the detail for number of sample is 1:

unsigned int i;                                 -->0(number of clock)

    // Reset ADC_value before read
    ADC_value[0]    = 0;                        -->6
    ADC_value[1]    = 0;                        -->13
    ADC_value[2]    = 0;                        -->18
    ADC_value[3]    = 0;                        -->19
    ADC_value[4]    = 0;                        -->24
    ADC_value[5]    = 0;                        -->25
    ADC_value[6]    = 0;                        -->30
    ADC_value[7]    = 0;                        -->31

    // Start SEQ1 convert
    AdcRegs.ADCTRL2.all = 0x2000;               -->36
// BP1
    for (i = 0; i < 1; i++)                        -->38                        -->254(check condition of i at the second time i=1)
    {
//BD2
         while (AdcRegs.ADCST.bit.INT_SEQ1== 0) {} // Wait for interrupt                        -->55
             AdcRegs.ADCST.bit.INT_SEQ1_CLR = 1;                        -->72

         // Get ADC value
         // Read AdcMirror.ADCRESULT register faster than AdcRegs.ADCRESULT
         ADC_value[0]   += (float)(AdcMirror.ADCRESULT0);                        -->78
         ADC_value[1]   += (float)(AdcMirror.ADCRESULT1);                        -->100
         ADC_value[2]   += (float)(AdcMirror.ADCRESULT2);                        -->120
         ADC_value[3]   += (float)(AdcMirror.ADCRESULT3);                        -->146
         ADC_value[4]   += (float)(AdcMirror.ADCRESULT4);                        -->166
         ADC_value[5]   += (float)(AdcMirror.ADCRESULT5);                        -->188
         ADC_value[6]   += (float)(AdcMirror.ADCRESULT6);                        -->208
         ADC_value[7]   += (float)(AdcMirror.ADCRESULT7);                        -->234
    }

    // Get average value
// BP3
    ADC_value[0]    = ADC_value[0] / 1;                        -->266
    ADC_value[1]    = ADC_value[1] / 1;                        -->352
    ADC_value[2]    = ADC_value[2] / 1;                        -->433
    ADC_value[3]    = ADC_value[3] / 1;                        -->518
    ADC_value[4]    = ADC_value[4] / 1;                        -->599
    ADC_value[5]    = ADC_value[5] / 1;                        -->684
    ADC_value[6]    = ADC_value[6] / 1;                        -->765
    ADC_value[7]    = ADC_value[7] / 1;                        -->850

Best regards,

Phien

When I use number of ADC sample is 1 in for function: it's 865, when number of sample is 10: it's 11677.

865 = 865*6.67nS = 5.7uS

11677 = 11677*6.67nS = 77uS

This seems fine but still feel its a bit more.

Regards,

Gautam