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Tool/software: Code Composer Studio
Dear Team,
I would like to generate below pulse using EPWM.
For every 31ms this pattern should be repeated.
As per my understanding Total period is 31ms and two low pulses should be generated with fixed width 540us and 910us.
As per my understanding if we take up-down counter and CMPA load with required value and counter compares with counter always, and if matches it checks AQCTLA for making high and low of EPWMA..
Kindly let me know is it possible to generate this kind of pulse using EPWM? If so please provide concept or piece of code.
Thank you.
Regards,
Upender Reddy M
Hi,
Thanks for the clarification.
Currently I am trying to generate pwm as mentioned above. Below is the my configuration and toggling of new period and Compare values for different pulse.
EPwm1Regs.TBPRD = 1406; period for 2ms
EPwm1Regs.CMPA.half.CMPA = 395; duty of 540 us
EPwm1Regs.TBCTR = 0; // clear TB counter
EPwm1Regs.TBCTL.bit.CTRMODE = TB_COUNT_UPDOWN; // Symmetric
EPwm1Regs.TBCTL.bit.PHSEN = TB_DISABLE; // Phase loading disabled
EPwm1Regs.TBCTL.bit.PRDLD = TB_SHADOW;
EPwm1Regs.TBCTL.bit.SYNCOSEL = TB_SYNC_DISABLE;
EPwm1Regs.TBCTL.bit.HSPCLKDIV = TB_DIV1; // TBCLK = SYSCLKOUT
EPwm1Regs.TBCTL.bit.CLKDIV = 6;//TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = CC_SHADOW;//CC_SHADOW;
EPwm1Regs.CMPCTL.bit.SHDWBMODE = CC_SHADOW;
EPwm1Regs.CMPCTL.bit.LOADAMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
// Interrupt where we will change the Compare Values
EPwm1Regs.ETSEL.bit.INTSEL = ET_CTR_ZERO;//ET_CTR_ZERO; // Select INT on Zero event
EPwm1Regs.ETSEL.bit.INTEN = 1; // Enable INT
EPwm1Regs.ETPS.bit.INTPRD = ET_1ST;//ET_3RD; // Generate INT on 3rd event
whenever interrupt comes below ISR iam toggling period and CompA values. Initial value of toggle is 0.
__interrupt void epwm1_isr(void)
{
// Update the CMPA and CMPB values
//update_compare(&epwm1_info);
toggle++;
if(toggle == 1)
{
EPwm1Regs.TBPRD = 1406;
EPwm1Regs.CMPA.half.CMPA = 395;
}
else if(toggle == 2)
{
EPwm1Regs.TBPRD = 20374;
EPwm1Regs.CMPA.half.CMPA = 510;
toggle=0;
}
else
{
}
// 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;
}
But iam able to see on scope period is changing ( 2ms and 29 ms) but width is not changing which is holding initial value(EPwm1Regs.CMPA.half.CMPA = 395;)
As per my understanding In shadow mode when TBCTR reaches zero,shadow register value will load into active register.
Kindly let me know how can I solve this? Please refer attach pulse file(hope previously also attached)
Thank you.
Regards,
Upender Reddy M
