contains a code sample showing initialization and run time for the waveforms in
the constant definitions in the device-specific header file.
Z
P
Z
P
TBCTR
EPWMxA
EPWMxB
CA
CA
CB
CB
A.
PWM period = 2 × TBPRD × TBCLK
B.
Rising edge and falling edge can be asymmetrically positioned within a PWM cycle. This allows for pulse placement techniques.
C.
Duty modulation for EPWMxA is set by CMPA and CMPB.
D.
Low time duty for EPWMxA is proportional to (CMPA + CMPB).
E.
To change this example to active high, CMPA and CMPB actions need to be inverted (that is, Set ! Clear and Clear Set).
F.
Duty modulation for EPWMxB is fixed at 50% (utilizes spare action resources for EPWMxB)
Figure 3-27. Up-Down-Count, Dual Edge Asymmetric Waveform, With Independent Modulation on
EPWMxA—Active Low
// Initialization Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.TBPRD = 600; // Period = 2 ´ 600 TBCLK counts
EPwm1Regs.CMPA.half.CMPA = 250; // Compare A = 250 TBCLK counts
EPwm1Regs.CMPB = 450; // Compare B = 450 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 = 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 CTR = Zero
EPwm1Regs.CMPCTL.bit.LOADBMODE = CC_CTR_ZERO; // load on CTR = Zero
EPwm1Regs.AQCTLA.bit.CAU = AQ_SET;
EPwm1Regs.AQCTLA.bit.CBD = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.ZRO = AQ_CLEAR;
EPwm1Regs.AQCTLB.bit.PRD = AQ_SET;
// Run Time
// = = = = = = = = = = = = = = = = = = = = = = = =
EPwm1Regs.CMPA.half.CMPA = EdgePosA; // adjust duty for output EPWM1A only
EPwm1Regs.CMPB = EdgePosB;
Enhanced Pulse Width Modulator (ePWM) Module
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
TMS320x2806x Microcontrollers
277
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
Страница 2: ......