TMS320F28032: PWM FREQUENCY

seyit yildirim

In the example HVPM_Sensorless Project in Control_Suite, the Pwm frequency specified in the software does not match the actual PWM frequency.

The PWM frequency is specified as 10KHz in the software. But in reality we measured it as 10.08 KHz. This causes the actual motor speed to be 1008 RPM, while it is processed as 1000 rpm in the software.

The situation does not change whether we use the internal clock or the Crystal oscillator. Looking forward to your help on the subject.

I am adding the relevant parts of the software below.

#define   PWM_FREQ_CUSTOM      10000

float32 T = (float32)1 / (float32)PWM_FREQ_CUSTOM;

**** @ main function

// Initialize PWM module           

pwm1.PeriodMax = SYSTEM_FREQUENCY*1000000*T/2;     

pwm1.HalfPerMax=pwm1.PeriodMax/2;   

pwm1.Deadband  = 0.9*SYSTEM_FREQUENCY;              

PWM_INIT_MACRO(1,2,3,pwm1)

****

And Device_Init Function is below:

void DeviceInit(void)
{
    WDogDisable(); // Disable the watchdog initially
    DINT;           // Global Disable all Interrupts
    IER = 0x0000;   // Disable CPU interrupts
    IFR = 0x0000;   // Clear all CPU interrupt flags


// Switch to Internal Oscillator 1 and turn off all other clock
// sources to minimize power consumption
    EALLOW;
    SysCtrlRegs.CLKCTL.bit.INTOSC1OFF = 0;
    SysCtrlRegs.CLKCTL.bit.OSCCLKSRCSEL=0;  // Clk Src = INTOSC1
    SysCtrlRegs.CLKCTL.bit.XCLKINOFF=1;     // Turn off XCLKIN
    SysCtrlRegs.CLKCTL.bit.XTALOSCOFF=1;    // Turn off XTALOSC
    SysCtrlRegs.CLKCTL.bit.INTOSC2OFF=1;    // Turn off INTOSC2

//    SysCtrlRegs.CLKCTL.bit.XCLKINOFF=1;//Turn off XCLKIN
//    SysCtrlRegs.CLKCTL.bit.XTALOSCOFF =0;// OSC on (default on reset)
//    SysCtrlRegs.CLKCTL.bit.OSCCLKSRCSEL=1;  // Clk Src = INTOSC1
//    SysCtrlRegs.CLKCTL.bit.INTOSC2OFF=1;    // Turn off INTOSC2
//    SysCtrlRegs.CLKCTL.bit.OSCCLKSRC2SEL=0;

    EDIS;


// SYSTEM CLOCK speed based on internal oscillator = 10 MHz
// 0xC =  60    MHz        (12)
// 0xB =  55    MHz        (11)
// 0xA =  50    MHz        (10)
// 0x9 =  45    MHz        (9)
// 0x8 =  40    MHz        (8)
// 0x7 =  35    MHz        (7)
// 0x6 =  30    MHz        (6)
// 0x5 =  25    MHz        (5)
// 0x4 =  20    MHz        (4)
// 0x3 =  15    MHz        (3)
// 0x2 =  10    MHz        (2)

    PLLset(0xC);    // choose from options above
//    PLLset(0x6);
// Initialise interrupt controller and Vector Table
// to defaults for now. Application ISR mapping done later.
    PieCntlInit();
    PieVectTableInit();

  EALLOW; // below registers are "protected", allow access.

// LOW SPEED CLOCKS prescale register settings
  SysCtrlRegs.LOSPCP.all = 0x0002;         // Sysclk / 4 (15 MHz)
  SysCtrlRegs.XCLK.bit.XCLKOUTDIV=2;


// ADC CALIBRATION 
//---------------------------------------------------
// The Device_cal function, which copies the ADC & oscillator calibration values
// from TI reserved OTP into the appropriate trim registers, occurs automatically
// in the Boot ROM. If the boot ROM code is bypassed during the debug process, the
// following function MUST be called for the ADC and oscillators to function according
// to specification.

    SysCtrlRegs.PCLKCR0.bit.ADCENCLK = 1; // Enable ADC peripheral clock
    (*Device_cal)();                        // Auto-calibrate from TI OTP
    SysCtrlRegs.PCLKCR0.bit.ADCENCLK = 0; // Return ADC clock to original state


// PERIPHERAL CLOCK ENABLES 
//---------------------------------------------------
// If you are not using a peripheral you may want to switch
// the clock off to save power, i.e. set to =0 
// 
// Note: not all peripherals are available on all 280x derivates.
// Refer to the datasheet for your particular device. 

  SysCtrlRegs.PCLKCR0.bit.ADCENCLK = 1;    // ADC
  //------------------------------------------------
  SysCtrlRegs.PCLKCR3.bit.COMP1ENCLK = 1;  // COMP1
  SysCtrlRegs.PCLKCR3.bit.COMP2ENCLK = 1;  // COMP2
  SysCtrlRegs.PCLKCR3.bit.COMP3ENCLK = 1;  // COMP3
  //------------------------------------------------
  SysCtrlRegs.PCLKCR1.bit.ECAP1ENCLK = 1;  //eCAP1
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.ECANAENCLK=0;   // eCAN-A
  //------------------------------------------------
  SysCtrlRegs.PCLKCR1.bit.EQEP1ENCLK = 1;  // eQEP1
  //------------------------------------------------
  SysCtrlRegs.PCLKCR1.bit.EPWM1ENCLK = 1;  // ePWM1
  SysCtrlRegs.PCLKCR1.bit.EPWM2ENCLK = 1;  // ePWM2
  SysCtrlRegs.PCLKCR1.bit.EPWM3ENCLK = 1;  // ePWM3
  SysCtrlRegs.PCLKCR1.bit.EPWM4ENCLK = 1;  // ePWM4
  SysCtrlRegs.PCLKCR1.bit.EPWM5ENCLK = 1;  // ePWM5
  SysCtrlRegs.PCLKCR1.bit.EPWM6ENCLK = 1;  // ePWM6
  SysCtrlRegs.PCLKCR1.bit.EPWM7ENCLK = 1;  // ePWM7
  SysCtrlRegs.PCLKCR0.bit.HRPWMENCLK = 0;    // HRPWM
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.I2CAENCLK = 0;   // I2C
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.LINAENCLK = 1;   // LIN-A
  //------------------------------------------------
  SysCtrlRegs.PCLKCR3.bit.CLA1ENCLK = 0;   // CLA1
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.SCIAENCLK = 1;  // SCI-A
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.SPIAENCLK = 0;   // SPI-A
  SysCtrlRegs.PCLKCR0.bit.SPIBENCLK = 0;     // SPI-B
  //------------------------------------------------
  SysCtrlRegs.PCLKCR0.bit.TBCLKSYNC = 1;   // Enable TBCLK
  //------------------------------------------------


//--------------------------------------------------------------------------------------
// GPIO (GENERAL PURPOSE I/O) CONFIG
//--------------------------------------------------------------------------------------
//-----------------------
// QUICK NOTES on USAGE:
//-----------------------
// If GpioCtrlRegs.GP?MUX?bit.GPIO?= 1, 2 or 3 (i.e. Non GPIO func), then leave
//   rest of lines commented
// If GpioCtrlRegs.GP?MUX?bit.GPIO?= 0 (i.e. GPIO func), then:
//   1) uncomment GpioCtrlRegs.GP?DIR.bit.GPIO? = ? and choose pin to be IN or OUT
//   2) If IN, can leave next to lines commented
//   3) If OUT, uncomment line with ..GPACLEAR.. to force pin LOW or
//                 uncomment line with ..GPASET.. to force pin HIGH or
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
//  GPIO-00 - PIN FUNCTION = PWM1A
    GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 1;         // 0=GPIO,  1=EPWM1A,  2=Resv,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO0 = 1;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO0 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO0 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-01 - PIN FUNCTION = PWM1B
    GpioCtrlRegs.GPAMUX1.bit.GPIO1 = 1;         // 0=GPIO,  1=EPWM1B,  2=Resv,  3=COMP1OUT
//   GpioCtrlRegs.GPADIR.bit.GPIO1 = 1;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO1 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO1 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-02 - PIN FUNCTION = PWM2A
    GpioCtrlRegs.GPAMUX1.bit.GPIO2 = 1;         // 0=GPIO,  1=EPWM2A,  2=Resv,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO2 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO2 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO2 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-03 - PIN FUNCTION = PWM2B
    GpioCtrlRegs.GPAMUX1.bit.GPIO3 = 1;         // 0=GPIO,  1=EPWM2B,  2=SPISOMI-A,  3=COMP2OUT
//   GpioCtrlRegs.GPADIR.bit.GPIO3 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO3 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO3 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-04 - PIN FUNCTION = PWM3A
    GpioCtrlRegs.GPAMUX1.bit.GPIO4 = 1;         // 0=GPIO,  1=EPWM3A,  2=Resv,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO4 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO4 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO4 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-05 - PIN FUNCTION = PWM3B
    GpioCtrlRegs.GPAMUX1.bit.GPIO5 = 1;         // 0=GPIO,  1=EPWM3B,  2=SPISIMO-A,  3=ECAP1
//   GpioCtrlRegs.GPADIR.bit.GPIO5 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO5 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO5 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-06 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX1.bit.GPIO6 = 0;         // 0=GPIO,  1=EPWM4A,  2=SYNCI,  3=SYNCO
//   GpioCtrlRegs.GPADIR.bit.GPIO6 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO6 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO6 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-07 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX1.bit.GPIO7 = 0;         // 0=GPIO,  1=EPWM4B,  2=SCIRX-A,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO7 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO7 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO7 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-08 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX1.bit.GPIO8 = 0;         // 0=GPIO,  1=EPWM5A,  2=Resv,  3=ADCSOC-A
//   GpioCtrlRegs.GPADIR.bit.GPIO8 = 0;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO8 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO8 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-09 - PIN FUNCTION = LIN_Tx
    GpioCtrlRegs.GPAMUX1.bit.GPIO9 = 2;         // 0=GPIO,  1=EPWM5B,  2=LINTX-A,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO9 = 1;          // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO9 = 1;  // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO9 = 1;          // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-10 - PIN FUNCTION = --PWMdebug--
    GpioCtrlRegs.GPAMUX1.bit.GPIO10 = 0;  // 0=GPIO,  1=EPWM6A,  2=Resv,  3=ADCSOC-B
   GpioCtrlRegs.GPADIR.bit.GPIO10 = 1;         // 1=OUTput,  0=INput
   GpioDataRegs.GPACLEAR.bit.GPIO10 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO10 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-11 - PIN FUNCTION = --unused--
    GpioCtrlRegs.GPAMUX1.bit.GPIO11 = 0;  // 0=GPIO,  1=EPWM6B,  2=LINRX-A,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO11 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO11 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO11 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-12 - PIN FUNCTION = POE
    GpioCtrlRegs.GPAMUX1.bit.GPIO12 = 1;  // 0=GPIO,  1=TZ1,  2=SCITX-A,  3=SPISIMO-B
//   GpioCtrlRegs.GPADIR.bit.GPIO12 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO12 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO12 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
//  GPIO-16 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO16 = 0;  // 0=GPIO,  1=SPISIMO-A,  2=Resv,  3=TZ2
//   GpioCtrlRegs.GPADIR.bit.GPIO16 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO16 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO16 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-17 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO17 = 0;  // 0=GPIO,  1=SPISOMI-A,  2=Resv,  3=TZ3
//   GpioCtrlRegs.GPADIR.bit.GPIO17 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO17 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO17 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-18 - PIN FUNCTION = AC info
    GpioCtrlRegs.GPAMUX2.bit.GPIO18 = 0;  // 0=GPIO,  1=SPICLK-A,  2=LINTX-A,  3=XCLKOUT
    GpioCtrlRegs.GPADIR.bit.GPIO18 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO18 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO18 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-19 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO19 = 0;  // 0=GPIO,  1=SPISTE-A,  2=LINRX-A,  3=ECAP1
//   GpioCtrlRegs.GPADIR.bit.GPIO19 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO19 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO19 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-20 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO20 = 0;  // 0=GPIO,  1=EQEPA-1,  2=Resv,  3=COMP1OUT
//   GpioCtrlRegs.GPADIR.bit.GPIO20 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO20 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO20 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-21 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO21 = 0;  // 0=GPIO,  1=EQEPB-1,  2=Resv,  3=COMP2OUT
//   GpioCtrlRegs.GPADIR.bit.GPIO21 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO21 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO21 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-22 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO22 = 0;  // 0=GPIO,  1=EQEPS-1,  2=Resv,  3=LINTX-A
//   GpioCtrlRegs.GPADIR.bit.GPIO22 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO22 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO22 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-23 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO23 = 0;  // 0=GPIO,  1=EQEPI-1,  2=Resv,  3=LINRX-A
//   GpioCtrlRegs.GPADIR.bit.GPIO23 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO23 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO23 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-24 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO24 = 0;  // 0=GPIO,  1=ECAP1,  2=Resv,  3=SPISIMO-B
//   GpioCtrlRegs.GPADIR.bit.GPIO24 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO24 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO24 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------


//  GPIO-28 - PIN FUNCTION = SCI-RX
    GpioCtrlRegs.GPAMUX2.bit.GPIO28 = 1;  // 0=GPIO,  1=SCIRX-A,  2=I2CSDA-A,  3=TZ2
//   GpioCtrlRegs.GPADIR.bit.GPIO28 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO28 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO28 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-29 - PIN FUNCTION = SCI-TX
    GpioCtrlRegs.GPAMUX2.bit.GPIO29 = 1;  // 0=GPIO,  1=SCITXD-A,  2=I2CSCL-A,  3=TZ3
//   GpioCtrlRegs.GPADIR.bit.GPIO29 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO29 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO29 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-30 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO30 = 0;  // 0=GPIO,  1=CANRX-A,  2=Resv,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO30 = 0;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO30 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO30 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-31 - PIN FUNCTION = unused
    GpioCtrlRegs.GPAMUX2.bit.GPIO31 = 0;  // 0=GPIO,  1=CANTX-A,  2=Resv,  3=Resv
//   GpioCtrlRegs.GPADIR.bit.GPIO31 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPACLEAR.bit.GPIO31 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPASET.bit.GPIO31 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
//  GPIO-32 - PIN FUNCTION = unused
    GpioCtrlRegs.GPBMUX1.bit.GPIO32 = 0;  // 0=GPIO,  1=I2CSDA-A,  2=SYNCI,  3=ADCSOCA
//   GpioCtrlRegs.GPBDIR.bit.GPIO32 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPBCLEAR.bit.GPIO32 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPBSET.bit.GPIO32 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-33 - PIN FUNCTION = unused
    GpioCtrlRegs.GPBMUX1.bit.GPIO33 = 0;  // 0=GPIO,  1=I2CSCL-A,  2=SYNCO,  3=ADCSOCB
//   GpioCtrlRegs.GPBDIR.bit.GPIO33 = 1;         // 1=OUTput,  0=INput
//   GpioDataRegs.GPBCLEAR.bit.GPIO33 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPBSET.bit.GPIO33 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//  GPIO-34 - PIN FUNCTION = LED3 on controlCARD
    GpioCtrlRegs.GPBMUX1.bit.GPIO34 = 0;  // 0=GPIO,  1=Resv,  2=Resv,  3=Resv
    GpioCtrlRegs.GPBDIR.bit.GPIO34 = 1;         // 1=OUTput,  0=INput
    GpioDataRegs.GPBCLEAR.bit.GPIO34 = 1; // uncomment if --> Set Low initially
//   GpioDataRegs.GPBSET.bit.GPIO34 = 1;         // uncomment if --> Set High initially
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
// GPIO 35-38 are defaulted to JTAG usage, and are not shown here to enforce JTAG debug
// usage. 
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
//--------------------------------------------------------------------------------------
    EDIS; // Disable register access
}

over 4 years ago

0 Ramesh Ramamoorthy over 4 years ago

TI__Mastermind 27240 points

Few things to note:

1. The accuracy of oscillator is the first thing to check. Make sure it is xx.0000MHz. If the crystal has deviation, it will definitely show up in the output, as the MCU peripheral is basically a timer based on its input clock.

2. The count value loaded in the PRD register should represent 100/2 microseconds in up-down mode, counting up for 50us and down for another 50us. The counter counts up from ZERO to PRD and back to ZERO.

0 seyit yildirim over 4 years ago in reply to Ramesh Ramamoorthy

Prodigy 45 points

How we can measure the SYSTEM_FREQUENCY used by MCU?

0 Ramesh Ramamoorthy over 4 years ago in reply to seyit yildirim

TI__Mastermind 27240 points

Am not sure if all the control cards facilitate bringing out sysclk. EPWM itself can help to see that. Just set the counter to swing from 0 to 9 and then drop down to 0 and count again to 9. Put it in up count mode adn see the output with a bit toggle in ISR or a EPWM output based on say a comp value of 4. See the output frequency, and multiply it by 10 to get the sysclk frequency.