[F28035] Simultaneous Writes to TBPRD Registers Between ePWM Modules problem

Tien Truong DUc

Other Parts Discussed in Thread: TMS320F28035

Dear all,

I am using TMS320F28035 for a variable frequency application, I used ePWM1 module as master and ePWM2 as slaver for control purpose.

when I update new TBPRD values, I see that the TBPRD values updated is not right.

I tried to fix and know that with ePWM type 2 or newer, EPWMXLINK register is used to prevents situations where a CTR = 0 or CTR = PRD pulse forces a
shadow to active load of these registers before all registers are updated between ePWM modules.

But ePWM of TMS320F28035 is type 1 and it does not have EPWMXLINK register.

Please tell me How can I Simultaneous Writes to TBPRD Registers Between ePWM Modules for TMS320F28035?

Thank you very much!

Brgs,

Tien

over 10 years ago

0 Gautam Iyer over 10 years ago

Guru 192875 points

Hi,

Check this link: e2e.ti.com/support/microcontrollers/c2000/f/171/p/389087/1377140

Regards,
Gautam

0 Tien Truong DUc over 10 years ago in reply to Gautam Iyer

Intellectual 615 points

Hi Gautam,

Thank you for your anwser, I think it is so helpful for me.
I will apply this post to fix my problem.

0 Tien Truong DUc over 10 years ago in reply to Gautam Iyer

Intellectual 615 points

Hi Gautam,

In my application, I only change TBPRD (updated in successive lines) to implement variable frequency but I keep TBPHS equal constant. Could you tell me why the situation that some registers being loaded from new shadow values while others are loaded from old shadow values can happen?

Thank you so much!

Additional information: I just keep TBPHS = 2 to compensate for logic delay from internal master module to slave modules.

.

0 Gautam Iyer over 10 years ago in reply to Tien Truong DUc

Guru 192875 points

Hi Tien,

Tien Truong DUc said:
Could you tell me why the situation that some registers being loaded from new shadow values while others are loaded from old shadow values can happen?

Is that so? I'm unaware of this fact or the description above. Devin Cottier can you have a look?

Regards,

Gautam

0 Tien Truong DUc over 10 years ago in reply to Gautam Iyer

Intellectual 615 points

Hi Gautam,

In the more detail of my application, after the frequency is changed, only master module is correctly updated PRD value, CTR of slave module count from TBPHS (not zero).

I tried to use the ISR of ePWM1 (master module) to update PRD values, but it make other ISR wrong (because they are in a group). How can I resolve it?

0 Gautam Iyer over 10 years ago in reply to Tien Truong DUc

Guru 192875 points

Hi Tien,

Try this: processors.wiki.ti.com/.../Interrupt_Nesting_on_C28x

Regards,
Gautam

0 Tien Truong DUc over 10 years ago in reply to Gautam Iyer

Intellectual 615 points

Hi Gautam,

I tried to update PRD value in ePWM1_ISR (100 - 200kHz) but I don't know what is wrong because the problem is still exist.
In the more detail, I enable ePWM1_INT in ePWM7_ISR (44kHz) as the above link ( processors.wiki.ti.com/.../Interrupt_Nesting_on_C28x) (in main function, I enable Global interrupt INTM, IER for group 3).
I think I still have a wrong step, when ePWM1_INT has higher interrupt priority than ePWM7_INT.
Could you tell me the way to correct this problem in the detail steps?

Thank you very much!

0 Tien Truong DUc over 10 years ago in reply to Gautam Iyer

Intellectual 615 points

Hi Gautam,

My detailed code (The CTR of ePWM2 is also not get zero):

In main():
PieCtrlRegs.PIEIER3.bit.INTx7 = 1; // Enable EPWM7 int in PIE group 3
IER |= M_INT3; // Enable CPU INT3 for capture interrupt
EINT; // Enable Global interrupt INTM
ERTM; // Enable Global realtime interrupt DBGM

In ePWM1_ISR (100 - 200kHz)
EPwm2Regs.TBPRD = LLC_CLA2C28x.TBPRD; // TBPRD is calculated with f=40kHz in CLA
EPwm1Regs.TBPRD = LLC_CLA2C28x.TBPRD;

EPwm1Regs.ETCLR.bit.INT = 1; // Enable ePWM7 INTN pulse
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;

In ePWM7_ISR(44kHz)

TempPIERIER = PieCtrlRegs.PIEIER3.all;

IFR |= M_INT3;
IER |= M_INT3;
PieCtrlRegs.PIEIFR3.bit.INTx1 = 1;
PieCtrlRegs.PIEIER3.all = 0x0001;
PieCtrlRegs.PIEACK.bit.ACK3 = 1;
asm (" NOP");
EINT;

………………// ISR_serviced

for (t1=1; t1<=10; t1++){}
DINT;
PieCtrlRegs.PIEIER3.all = TempPIERIER;
EPwm7Regs.ETCLR.bit.INT = 1; // Enable ePWM7 INTN pulse
PieCtrlRegs.PIEACK.all = PIEACK_GROUP3;
return;

In addition,

EPwm2Regs.TBPHS.half.TBPHS =2; (shadow mode, up-down counter)

0 Tien Truong DUc over 10 years ago in reply to Tien Truong DUc

Intellectual 615 points

Vishal_Coelho, could you help me?

0 Gautam Iyer over 10 years ago in reply to Tien Truong DUc

Guru 192875 points

Let me help you get Vishal_Coelho here...

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[F28035] Simultaneous Writes to TBPRD Registers Between ePWM Modules problem