TBCTR
EPWMxA
EPWMxB
TBPRD
value
CAZ P CB Z P CB CA Z P
Z P CA Z P CA Z PCBCB
Action-Qualifier (AQ) Submodule
Figure 2-21. Up, Single Edge Asymmetric Waveform, With Independent Modulation on EPWMxA and
EPWMxB—Active High
A PWM period = (TBPRD + 1 ) × T
TBCLK
B Duty modulation for EPWMxA is set by CMPA, and is active high (that is, high time duty proportional to CMPA).
C Duty modulation for EPWMxB is set by CMPB and is active high (that is, high time duty proportional to CMPB).
D The "Do Nothing" actions ( X ) are shown for completeness, but will not be shown on subsequent diagrams.
E Actions at zero and period, although appearing to occur concurrently, are actually separated by one TBCLK period.
TBCTR wraps from period to 0000.
Example 2-2 contains a code sample showing initialization and run time for the waveforms in Figure 2-21 .
Example 2-2. Code Sample for Figure 2-21
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600; // Period = 601 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 350; // Compare A = 350 TBCLK counts
EPwm1Regs.CMPB = 200; // Compare B = 200 TBCLK counts
EPwm1Regs.TBPHS = 0; // Set Phase register to zero
EPwm1Regs.TBCTR = 0; // clear TB counter
EPwm1Regs.TBCTL.bit.CTRMODE = TB_UP;
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 = SYSCLK
EPwm1Regs.TBCTL.bit.CLKDIV = TB_DIV1;
EPwm1Regs.CMPCTL.bit.SHDWAMODE = 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.ZRO = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_SET;
EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A
EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B
SPRU791D – November 2004 – Revised October 2007 ePWM Submodules 43
Submit Documentation Feedback
To Next Page
Loading...
Need help?
General
