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TIMERS

nishanth p
Intellectual 395 points


Hi,

What is the diff btwn adc frequency(12.5MHz) and sampling frequency(which is given by the CPU timer0 )

  • 0
    TI__Guru 55700 points

    Nishanth,

    Sampling frequency given in CPU Timers? Please clarify your question.

    -Manoj

     

  • 0 in reply to Manoj Santha Mohan
    Intellectual 395 points

    herewith am copying the text given in manual.  I have run the program & got O/p but want to understand the following paragraph,

     


    To start the ADC we will use our time-base, the CPU-Timer 0. In file “Lab17.c” this timer is still initialized to 100 microseconds from an earlier lab. For the new exercise, we would like to use a sample frequency of 50 kHz or a period of 20 microseconds. Change the line to initialize the CPU-timer 0 to:
    ConfigCpuTimer(&CpuTimer0,150,20);
    In the function “cpu_timer0_isr()”, which is triggered by Timer 0 once every 20 mi-croseconds, add a line to start the ADC by software:
    AdcRegs.ADCTRL2.bit.SOC_SEQ1 = 1;

  • 0 in reply to nishanth p
    Intellectual 970 points

    You are firing interrupts every 20 us and in each of those interrupts you are manually triggering the ADC by writing to the Start of Conversion (SOC) bit to enable conversions. Because of the 50 kHz frequency of Timer0, you are effectively sampling at a 50 kHz frequency. I think the ADC frequency you referred to in your first post was the frequency at which the peripheral is being clocked at.