Action-qualifier (AQ) Module
AQCTLA[15:0]
Action-qualifier control A
EPWMA
EPWMB
TBCLK
CTR = PRD
CTR = 0
CTR = CMPA
CTR = CMPB
CTR_dir
AQCTLB[15:0]
Action-qualifier control B
AQSFRC[15:0]
Action-qualifier S/W force
AQCSFRC[3:0] (shadow)
continuous S/W force
AQCSFRC[3:0] (active)
continuous S/W force
Enhanced PWM (ePWM) Module
The action-qualifier submodule is based on event-driven logic. It can be thought of as a programmable
cross switch with events at the input and actions at the output, all of which are software controlled via the
set of registers shown in
. The possible input events are summarized again in
Figure 15-24. Action-Qualifier Submodule Inputs and Outputs
Table 15-16. Action-Qualifier Submodule Possible Input Events
Signal
Description
Registers Compared
CTR = PRD
Time-base counter equal to the period value
TBCNT = TBPRD
CTR = 0
Time-base counter equal to zero
TBCNT = 0000h
CTR = CMPA
Time-base counter equal to the counter-compare A
TBCNT = CMPA
CTR = CMPB
Time-base counter equal to the counter-compare B
TBCNT = CMPB
Software forced event
Asynchronous event initiated by software
The software forced action is a useful asynchronous event. This control is handled by registers AQSFRC
and AQCSFRC.
The action-qualifier submodule controls how the two outputs EPWMxA and EPWMxB behave when a
particular event occurs. The event inputs to the action-qualifier submodule are further qualified by the
counter direction (up or down). This allows for independent action on outputs on both the count-up and
count-down phases.
The possible actions imposed on outputs EPWMxA and EPWMxB are:
•
Set High: Set output EPWMxA or EPWMxB to a high level.
•
Clear Low: Set output EPWMxA or EPWMxB to a low level.
•
Toggle: If EPWMxA or EPWMxB is currently pulled high, then pull the output low. If EPWMxA or
EPWMxB is currently pulled low, then pull the output high.
•
Do Nothing: Keep outputs EPWMxA and EPWMxB at same level as currently set. Although the "Do
Nothing" option prevents an event from causing an action on the EPWMxA and EPWMxB outputs, this
event can still trigger interrupts. See the event-trigger submodule description in
for
details.
1517
SPRUH73H – October 2011 – Revised April 2013
Pulse-Width Modulation Subsystem (PWMSS)
Copyright © 2011–2013, Texas Instruments Incorporated