Texas Instrument Picollo A(F28027) ePWM as Start of Conversion(SOC)

[Sulaiman (Gast)]

Hi Guys,
I'm a newbie in µC Programming.
I have a question to the Example Programme,which I got from TExas 
Instrument. The Programm reads ADC Input and convert it into digital 
value.
From this example, i want to change my sampling frequency. Can anybody 
help me how can I do it?Any help would be really apreciated. ;-)

This is my main Function
main()
{
// Step 1. Initialize System Control:
// PLL, WatchDog, enable Peripheral Clocks
// This example function is found in the DSP2803x_SysCtrl.c file.
   InitSysCtrl();


// Step 2. Initialize GPIO:
// This example function is found in the DSP2802x_Gpio.c file and
// illustrates how to set the GPIO to it's default state.
// InitGpio();  // Skipped for this example

// Step 3. Clear all interrupts and initialize PIE vector table:
// Disable CPU interrupts
   DINT;

// Initialize the PIE control registers to their default state.
// The default state is all PIE interrupts disabled and flags
// are cleared.
// This function is found in the DSP2802x_PieCtrl.c file.
   InitPieCtrl();

// Disable CPU interrupts and clear all CPU interrupt flags:
   IER = 0x0000;
   IFR = 0x0000;

// Initialize the PIE vector table with pointers to the shell Interrupt
// Service Routines (ISR).
// This will populate the entire table, even if the interrupt
// is not used in this example.  This is useful for debug purposes.
// The shell ISR routines are found in DSP2802x_DefaultIsr.c.
// This function is found in DSP2802x_PieVect.c.
   InitPieVectTable();

// Interrupts that are used in this example are re-mapped to
// ISR functions found within this file.
   EALLOW;  // This is needed to write to EALLOW protected register
   PieVectTable.ADCINT1 = &adc_isr;
   EDIS;    // This is needed to disable write to EALLOW protected 
registers

// Step 4. Initialize all the Device Peripherals:
// This function is found in DSP2802x_InitPeripherals.c
// InitPeripherals();       // Not required for this example
   InitAdc();          // For this example, init the ADC

// Step 5. User specific code, enable interrupts:

// Enable ADCINT1 in PIE
   PieCtrlRegs.PIEIER1.bit.INTx1 = 1;  // Enable INT 1.1 in the PIE
   IER |= M_INT1;       // Enable CPU Interrupt 1
   EINT;                // Enable Global interrupt INTM
   ERTM;                // Enable Global realtime interrupt DBGM

   LoopCount = 0;
   ConversionCount = 0;

// Configure ADC auf Kanal A
EALLOW;
AdcRegs.ADCCTL1.bit.INTPULSEPOS  = 1;    //ADCINT1 trips after 
AdcResults latch
AdcRegs.INTSEL1N2.bit.INT1E     = 1;  //Enabled ADCINT1
AdcRegs.INTSEL1N2.bit.INT1CONT  = 0;  //Disable ADCINT1 Continuous mode
AdcRegs.INTSEL1N2.bit.INT1SEL  = 1;  //setup EOC1 to trigger ADCINT1 to 
fire
AdcRegs.ADCSOC0CTL.bit.CHSEL   = 0;  //set SOC0 channel select to 
ADCINA0
AdcRegs.ADCSOC0CTL.bit.TRIGSEL   = 5;  //set SOC0 start trigger on 
EPWM1A, due to round-robin SOC0 converts first then SOC1
AdcRegs.ADCSOC0CTL.bit.ACQPS   = 6;  //set SOC0 S/H Window to 7 ADC 
Clock Cycles, (6 ACQPS plus 1)
//  AdcRegs.ADCOFFTRIM.bit.OFFTRIM = 5;    //Apply artificial offset 
(+80) to account for a negative offset that may reside in the ADC core
EDIS;

//Configure ePWM1 auf Kanal A
// Assumes ePWM1 clock is already enabled in InitSysCtrl();
   EPwm1Regs.ETSEL.bit.SOCAEN  = 1;  // Enable SOC on A group
   EPwm1Regs.ETSEL.bit.SOCASEL  = 4;  // Select SOC from from CPMA on 
upcount
   EPwm1Regs.ETPS.bit.SOCAPRD   = 1;  // Generate pulse on 1st event
   EPwm1Regs.CMPA.half.CMPA   = 0x0080;       // Set compare A value
   EPwm1Regs.TBPRD     = 0xFFFF;  // Set period for ePWM1
   EPwm1Regs.TBCTL.bit.CTRMODE   = 0;    // count up and start


// Wait for ADC interrupt
   for(;;){
      LoopCount++;
   }
}

interrupt void  adc_isr(void){}