• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 83 subscribers
  • Views 467 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

problem update AQCTLA register in epwm interrupt service routine.

Ankit Gupta6
Intellectual 565 points
Other Parts Discussed in Thread: TMS320F28335, CONTROLSUITE

Hi,

I am working on implementing Manchester encoding algorithm using epwm1 on DSp TMS320F28335.

i am trying to update the EPwm1Regs.AQCTLA.bit.ZRO and EPwm1Regs.AQCTLA.bit.CAU register for every interrupt based on the value of current bit that needs to be encoded and next in line bit (following Manchester encoding) .

However, the output i see on the oscilloscope is not having the updated result. it always follows the EPwm1Regs.AQCTLA.bit.ZRO and EPwm1Regs.AQCTLA.bit.CAU register that i have defined during initialization.

I checked my code using breakpoints and the resisters in question updates as i require them to be, however the output remains the same.

here is my code for ISR and initialization,

 

interrupt void epwm1_isr(void)
{
if(flag==1)
{EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.ZRO = AQ_CLEAR;
EPwm1Regs.CMPA.half.CMPA = 1500;
}

if(flag==0)
{
epwm1value= nextvalue[j];

if (epwm1value == 1)
{
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.CMPA.half.CMPA = 750;
}
else
{EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm1Regs.CMPA.half.CMPA = 750;
}

if(nextvalue[j]== nextvalue[j+1])
{EPwm1Regs.AQCTLA.bit.ZRO = AQ_TOGGLE;
}
else
{EPwm1Regs.AQCTLA.bit.ZRO = AQ_NO_ACTION;
}

j++;
if(j>15)
{j=0;
flag=1;
}
}

EPwm1TimerIntCount++;
// Clear INT flag for this timer
EPwm1Regs.ETCLR.bit.INT = 1;

// Acknowledge this interrupt to receive more interrupts from group 3

PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;

}

void InitEPwm1Example()
{

EPwm1Regs.TBPRD = 1500; // Set timer period
EPwm1Regs.TBPHS.half.TBPHS = 0x0000; // Phase is 0
EPwm1Regs.TBCTR = 0x0000; // Clear counter

// Setup TBCLK
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UP; // Count up
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Disable phase loading
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // Clock ratio to SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;

// Setup compare
EPwm1Regs.CMPA.half.CMPA = 100;

// Set actions
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET; // Set PWM1A on Zero
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLA.bit.ZRO = AQ_CLEAR;

EPwm1Regs.AQCTLB.bit.CAU = AQ_SET; // Set PWM1B on Zero
EPwm1Regs.AQCTLB.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR;

// Active Low PWMs - Setup Deadband
EPwm1Regs.DBCTL.bit.OUT_MODE = 0x0;
EPwm1Regs.DBCTL.bit.POLSEL = DB_ACTV_LO;
EPwm1Regs.DBCTL.bit.IN_MODE = DBA_ALL;
EPwm1Regs.DBRED = EPWM1_MIN_DB;
EPwm1Regs.DBFED = EPWM1_MIN_DB;
EPwm1_DB_Direction = DB_UP;

// Interrupt where we will change the Deadband
EPwm1Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO; // Select INT on Zero event
EPwm1Regs.ETSEL.bit.INTEN = 1; // Enable INT
EPwm1Regs.ETPS.bit.INTPRD = ET_1ST; // Generate INT on 3rd event


}

is there something i am missing ? or can we not update the AQCTLA register during run time?

  • 0
    TI__Expert 5940 points
    Hello,

    I recommend checking the initialization code in the controlSUITE ePWM examples at:
    controlSUITE\device_support\f2833x\v141\DSP2833x_examples_ccsv5

    Comparing the example configuration code with your project can help with debugging. If you haven't already, I also recommend putting break points in the ISRs to ensure that the interrupts are generated as expected and check the logic of conditional blocks within the ISRs that write to the ePWM registers.

    Are you able to write to the AQCLTA registers through the Registers window in the CCS debug perspective? If so, you may rule out possible hardware issues.

    Elizabeth
  • 0 in reply to Elizabeth Joy
    Intellectual 565 points
    Hi Elizabeth,

    I placed breakpoints in ISR and checked each and every bit of AQCLTA register. They are updating as i require them to be. I am sure about the initialization part as this is what i have used in the past and has worked good for me in other projects.
    I think it has something to do with the non availability of shadow registers for AQCLTA. I think because of no shadow register s for AQCLTA even if i am updating the registers in run time they are not being transmitted to the output. Not really sure, just my speculation. Can you confirm?

    -Ankit
  • 0 in reply to Ankit Gupta6
    TI__Genius 15260 points
    Hi Ankit,

    What GPIOs are you using to output the PWM signal? Have you configured the GPIO muxing options to select the ePWM?

    Can you try to simplify your ISR? For example just for debug, try commenting out all of the IF statements and just setting the CAU action to TOGGLE and keeping the CAU value constant. If that works, then we can continue the debug and add some of the complexity back. If it doesn't work, then we likely have a PWM or a pin configuration issue.

    Kris