Texas Instruments TMS320x28xx, 28xxx Action-Qualifier Submodule Possible Input Events, ∙ Set High

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Action-Qualifier (AQ) Submodule

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 Table 2-6.

Figure 2-18. Action-Qualifier Submodule Inputs and Outputs

TBCLK

CTR￿=￿PRD

CTR￿=￿Zero

CTR￿=￿CMPA

CTR￿=￿CMPB

CTR_dir

Action-qualifier￿(AQ)￿Module

AQCTLA[15:0]

Action-qualifier￿control￿A

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

EPWMA

EPWMB

For convenience, the possible input events are summarized again in Table 2-7.

Table 2-7. Action-Qualifier Submodule Possible Input Events

Signal	Description	Registers Compared
CTR = PRD	Time-base counter equal to the period value	TBCTR = TBPRD
CTR = Zero	Time-base counter equal to zero	TBCTR = 0x0000
CTR = CMPA	Time-base counter equal to the counter-compare A	TBCTR = CMPA
CTR = CMPB	Time-base counter equal to the counter-compare B	TBCTR = 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 and ADC start of conversion. See the Event-trigger Submodule description in Section 2.8 for details.

38 ePWM Submodules SPRU791D–November 2004–Revised October 2007

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