Chapter 15 Pulse-Width Modulation Subsystem (PWMSS).
Chapter 15 Pulse-Width Modulation Subsystem (PWMSS).
Chapter 15 Pulse-Width Modulation Subsystem (PWMSS).
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Enhanced PWM (ePWM) Module www.ti.com<br />
The action-qualifier submodule is based on event-driven logic. It can be thought of as a programmable<br />
cross switch with events at the input and actions at the output, all of which are software controlled via the<br />
set of registers shown in Figure <strong>15</strong>-24. The possible input events are summarized again in Table <strong>15</strong>-16.<br />
TBCLK<br />
CTR = PRD<br />
CTR = 0<br />
CTR = CMPA<br />
CTR = CMPB<br />
CTR_dir<br />
Figure <strong>15</strong>-24. Action-Qualifier Submodule Inputs and Outputs<br />
Action-qualifier (AQ) Module<br />
AQCTLA[<strong>15</strong>:0]<br />
Action-qualifier control A<br />
AQCTLB[<strong>15</strong>:0]<br />
Action-qualifier control B<br />
AQSFRC[<strong>15</strong>:0]<br />
Action-qualifier S/W force<br />
AQCSFRC[3:0] (shadow)<br />
continuous S/W force<br />
AQCSFRC[3:0] (active)<br />
continuous S/W force<br />
EPWMA<br />
EPWMB<br />
Table <strong>15</strong>-16. Action-Qualifier Submodule Possible Input Events<br />
Signal Description Registers Compared<br />
CTR = PRD Time-base counter equal to the period value TBCNT = TBPRD<br />
CTR = 0 Time-base counter equal to zero TBCNT = 0000h<br />
CTR = CMPA Time-base counter equal to the counter-compare A TBCNT = CMPA<br />
CTR = CMPB Time-base counter equal to the counter-compare B TBCNT = CMPB<br />
Software forced event Asynchronous event initiated by software<br />
The software forced action is a useful asynchronous event. This control is handled by registers AQSFRC<br />
and AQCSFRC.<br />
The action-qualifier submodule controls how the two outputs EPWMxA and EPWMxB behave when a<br />
particular event occurs. The event inputs to the action-qualifier submodule are further qualified by the<br />
counter direction (up or down). This allows for independent action on outputs on both the count-up and<br />
count-down phases.<br />
The possible actions imposed on outputs EPWMxA and EPWMxB are:<br />
• Set High: Set output EPWMxA or EPWMxB to a high level.<br />
• Clear Low: Set output EPWMxA or EPWMxB to a low level.<br />
• Toggle: If EPWMxA or EPWMxB is currently pulled high, then pull the output low. If EPWMxA or<br />
EPWMxB is currently pulled low, then pull the output high.<br />
• Do Nothing: Keep outputs EPWMxA and EPWMxB at same level as currently set. Although the "Do<br />
Nothing" option prevents an event from causing an action on the EPWMxA and EPWMxB outputs, this<br />
event can still trigger interrupts. See the event-trigger submodule description in Section <strong>15</strong>.2.2.9 for<br />
details.<br />
1646 <strong>Pulse</strong>-<strong>Width</strong> <strong>Modulation</strong> <strong>Subsystem</strong> (<strong>PWMSS</strong>) SPRUH73E–October 2011–Revised May 2012<br />
Submit Documentation Feedback<br />
Copyright © 2011–2012, Texas Instruments Incorporated
Change language