TMS320F28069: Questions about register writing

Yu Qi1

Part Number: TMS320F28069

Hi, there. I'm currently using F28069 and using the interrupt of ECAP2 which serves in APWM mode. I have enabled the interrupt when CTR reaches CMP and here is my interrupt service function

__interrupt void ecap2_isr(void){
    GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;

    ECap2Regs.ECCLR.bit.INT = 1;
    ECap2Regs.ECCLR.bit.CTR_EQ_CMP = 1;
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
}

I expected to see a pulsed waveform whose duty is approximately 50% and frequence is half of the APWM. But actually, when I ran the program, I found the duty is very small (close to 0) and the frequency is the same as APWM. So I think probably there is some problem with my interrupt flag clearing process and it triggers the interrupt function being operated two times in each APWM cycle.

After that, I have made a modification. I change the order of two lines of the code above ,which is shown below

__interrupt void ecap2_isr(void){
    GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;
    
    ECap2Regs.ECCLR.bit.CTR_EQ_CMP = 1;
    ECap2Regs.ECCLR.bit.INT = 1;
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
}

And the waveform turned to be the same as I expected. But I have no idea about this phenomenon, could you please give me some information related to this weird thing? Thank you.

over 4 years ago

0 Santosh Jha over 4 years ago

TI__Guru 50611 points

Hi,

Can you try putting that code in

EALLOW;

EDIS;

0 Yu Qi1 over 4 years ago in reply to Santosh Jha

Prodigy 100 points

Hi, thank you for your reply. I think that might not be the issue since the two register, GPATOGGLE and ECCLR, are not EALLOW protected though I haven't tried that yet.

0 Santosh Jha over 4 years ago in reply to Yu Qi1

TI__Guru 50611 points

Hi,

Please try this or I will try to recreate the issue on my setup tomorrow.

0 Yu Qi1 over 4 years ago in reply to Santosh Jha

Prodigy 100 points

Hi Santosh. I have tried to put EALLOW and EDIS and here is my code

__interrupt void ecap2_isr(void){
    EALLOW;
    GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;
    ECap2Regs.ECCLR.bit.INT = 1;
    ECap2Regs.ECCLR.bit.CTR_EQ_CMP = 1;
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
    EDIS;
}

And here is my waveform captured.

The top two channels are the output of APWM and the last channel is the GPIO0. As you can see, the frequency of channel2 is the same as channel 0 and channel1, which is not what I'm expecting. Besides, the pulse duration of GPIO0 is quite small, almost 500ns(the period is 500us), which is also weird.

When I modified the code as

__interrupt void ecap2_isr(void){
    EALLOW;
    GpioDataRegs.GPATOGGLE.bit.GPIO0 = 1;
    ECap2Regs.ECCLR.bit.CTR_EQ_CMP = 1;
    ECap2Regs.ECCLR.bit.INT = 1;
    PieCtrlRegs.PIEACK.all = PIEACK_GROUP4;
    EDIS;
}

Then, the waveform is exactly what I expected, which is put below.

In order that you can completely recreate this issue, I put my ECAP initialization code as below.

void initAPWM(){
    ECap1Regs.ECEINT.all = 0x0000;             // Disable all capture interrupts
    ECap1Regs.ECCLR.all = 0xFFFF;              // Clear all CAP interrupt flags
    ECap1Regs.ECCTL2.bit.CAP_APWM = 1;   // Enable APWM mode
    ECap2Regs.ECCTL2.bit.CAP_APWM = 1;   // Enable APWM mode


    ECap2Regs.ECEINT.bit.CTR_EQ_CMP = 1; //Enable APWM interrupt when CTR equals CMP
//    ECap2Regs.ECEINT.bit.CEVT2 = 1;

    ECap1Regs.ECCLR.all = 0x0FF;         // Clear pending interrupts

    ECap1Regs.ECCTL2.bit.APWMPOL = 1;
    ECap2Regs.ECCTL2.bit.APWMPOL = 0;
    ECap1Regs.CAP1 = pwm1_prd;         // Set Period value
    ECap1Regs.CAP2 = pwm1_cmp;         // Set Compare value
//
    ECap2Regs.CAP1 = pwm2_prd;         // Set Period value
    ECap2Regs.CAP2 = pwm2_cmp;         // Set Compare value
    // Start counters
    ECap1Regs.ECCTL2.bit.TSCTRSTOP = 1;
    ECap2Regs.ECCTL2.bit.TSCTRSTOP = 1;

    ECap1Regs.ECCTL2.bit.SYNCO_SEL = 1;
    ECap2Regs.ECCTL2.bit.SYNCI_EN = 1;
    ECap2Regs.CTRPHS  = pwm2_pha;         // Set Compare value
}

Thank you.

0 Santosh Jha over 4 years ago in reply to Yu Qi1

TI__Guru 50611 points

Hi,

Do you have sample project which I can try?

C2000™︎ microcontrollers

C2000 microcontrollers forum

TMS320F28069: Questions about register writing