Specifications

2.3 Counter-Compare (CC) Submodule
CTR = CMPB
CTR = CMPA
CTR_Dir
CTR = 0
CTR = PRD
Dead
Band
(DB)
Counter
Compare
(CC)
Action
Qualifier
(AQ)
EPWMxA
EPWMxB
CTR = CMPB
CTR = 0
EPWMxINT
EPWMxSOCA
EPWMxSOCB
EPWMxA
EPWMxB
TZ1
to TZ6
CTR = CMPA
Time-Base
(TB)
CTR = PRD
CTR = 0
CTR_Dir
EPWMxSYNCI
EPWMxSYNCO
EPWMxTZINT
PWM-
chopper
(PC)
Event
Trigger
and
Interrupt
(ET)
Trip
Zone
(TZ)
GPIO
MUX
ADC
PIE
PIE
2.3.1 Purpose of the Counter-Compare Submodule
www.ti.com Counter-Compare (CC) Submodule
Figure 2-11 illustrates the counter-compare submodule within the ePWM.
Figure 2-11. Counter-Compare Submodule
Figure 2-12 shows the basic structure of the counter-compare submodule.
The counter-compare submodule takes as input the time-base counter value. This value is continuously
compared to the counter-compare A (CMPA) and counter-compare B (CMPB) registers. When the
time-base counter is equal to one of the compare registers, the counter-compare unit generates an
appropriate event.
The counter-compare:
• Generates events based on programmable time stamps using the CMPA and CMPB registers
– CTR = CMPA: Time-base counter equals counter-compare A register (TBCTR = CMPA).
– CTR = CMPB: Time-base counter equals counter-compare B register (TBCTR = CMPB)
• Controls the PWM duty cycle if the action-qualifier submodule is configured appropriately
• Shadows new compare values to prevent corruption or glitches during the active PWM cycle
SPRU791F – November 2004 – Revised July 2009 ePWM Submodules 33
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