When using this configuration in practice, if you load CMPA/CMPB on zero, then use CMPA/CMPB values
greater than or equal to 1. If you load CMPA/CMPB on period, then use CMPA/CMPB values less than or equal
to TBPRD-1. This means there will always be a pulse of at least one TBCLK cycle in a PWM period which, when
very short, tend to be ignored by the system.
UP
DOWN
UP
DOWN
2
0
3
4
1
2
3
1
2
0
3
4
1
2
0
3
1
TBCTR
TBCTR Direction
EPWMxA/EPWMxB
Case 2:
CMPA = 3, 25% Duty
Case 3:
CMPA = 2, 50% Duty
Case 3:
CMPA = 1, 75% Duty
Case 4:
CMPA = 0, 100% Duty
Case 1:
CMPA = 4, 0% Duty
EPWMxA/EPWMxB
EPWMxA/EPWMxB
EPWMxA/EPWMxB
EPWMxA/EPWMxB
Mode: Up-Down Count
TBPRD = 4
CAU = SET, CAD = CLEAR
0% - 100% Duty
Figure 3-21. Up-Down-Count Mode Symmetrical Waveform
show some common action-qualifier configurations.
shows how to configure an ePWM module for each
case. Some conventions used in the figures and examples are as follows:
• TBPRD, CMPA, and CMPB refer to the value written in their respective registers. The active register, not the
shadow register, is used by the hardware.
• CMPx, refers to either CMPA or CMPB.
• EPWMxA and EPWMxB refer to the output signals from ePWMx
• Up-Down means Count-up-and-down mode, Up means up-count mode and Dwn means down-count mode
• Sym = Symmetric, Asym = Asymmetric
Enhanced Pulse Width Modulator (ePWM) Module
270
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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