contains a code sample showing initialization and run time for the waveforms
constant definitions in the device-specific header file.
TBCTR
EPWMxA
EPWMxB
TBPRD
value
CA
T
Z
T
Z
T
Z
CA
CB
CB
A.
PWM frequency = 1/( (TBPRD + 1 ) × T
TBCLK
)
B.
Pulse can be placed anywhere within the PWM cycle (0000 - TBPRD)
C.
High time duty proportional to (CMPB - CMPA)
D.
EPWMxB can be used to generate a 50% duty square wave with frequency =
�
× ( (TBPRD + 1 ) × TBCLK )
Figure 3-24. Up-Count, Pulse Placement Asymmetric Waveform With Independent Modulation on
EPWMxA
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600; // Period = 601 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 200; // Compare A = 200 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_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 = SYSCLKOUT
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 TBCTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on TBCTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CBU = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_TOGGLE;
//
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = EdgePosA; // adjust duty for output EPWM1A only
EPwm1Regs.CMPB = EdgePosB;
Enhanced Pulse Width Modulator (ePWM) Module
274
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Summary of Contents for TMS320 2806 Series
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