Texas Instruments TMS570LC4357

CA CA CA
CA
CB CB
CB
CB
TBCTR
EPWMxA
EPWMxB
TBPRD
value
ePWM Submodules www.ti.com
2026
SPNU563A–March 2018
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Copyright © 2018, Texas Instruments Incorporated
Enhanced Pulse Width Modulator (ePWM) Module
Figure 35-25. Up-Down-Count, Dual Edge Symmetric Waveform, With Independent Modulation on
EPWMxA and EPWMxB — Complementary
A PWM period = 2 × TBPRD × T
TBCLK
B Duty modulation for EPWMxA is set by CMPA, and is active low, i.e., low time duty proportional to CMPA
C Duty modulation for EPWMxB is set by CMPB and is active high, i.e., high time duty proportional to CMPB
D Outputs EPWMx can drive upper/lower (complementary) power switches
E Dead-band = CMPB - CMPA (fully programmable edge placement by software). Note the dead-band module is also
available if the more classical edge delay method is required.
Example 35-5 contains a code sample showing initialization and run time for the waveforms in Figure 35-
25.
Example 35-5. Code Sample for Figure 35-25
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600; // Period = 2´600 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 350; // Compare A = 350 TBCLK counts
EPwm1Regs.CMPB = 400; // Compare B = 400 TBCLK counts
EPwm1Regs.TBPHS = 0; // Set Phase register to zero
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 = VCLK3
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.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CAD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.CBD = AQ_SET;
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = Duty1A; // adjust duty for output EPWM1A
EPwm1Regs.CMPB = Duty1B; // adjust duty for output EPWM1B