PIE
Event Trigger
Module Logic
CTR=Zero
CTR=PRD
CTR=CMPA
EPWMxINTn
CTR=CMPB
CTR_dir
Direction
qualifier
CTRU=CMPA
ETSEL reg
EPWMxSOCA
/n
/n
/n
EPWMxSOCB
ADC
clear
count
count
clear
count
clear
CTRD=CMPA
CTRU=CMPB
CTRD=CMPB
ETPS reg
ETFLG reg
ETCLR reg
ETFRC reg
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ePWM Submodules
271
SPRUI07–March 2020
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Enhanced Pulse Width Modulator (ePWM) Module
The event-trigger submodule monitors various event conditions (the left side inputs to event-trigger
submodule shown in Figure 3-41) and can be configured to prescale these events before issuing an
Interrupt request or an ADC start of conversion. The event-trigger prescaling logic can issue Interrupt
requests and ADC start of conversion at:
• Every event
• Every second event
• Every third event
Figure 3-41. Event-Trigger Submodule Showing Event Inputs and Prescaled Outputs
The key registers used to configure the event-trigger submodule are shown in Table 3-20:
Table 3-20. Event-Trigger Submodule Registers
Register Name Address offset Shadowed Description
ETSEL 0x0019 No Event-trigger Selection Register
ETPS 0x001A No Event-trigger Prescale Register
ETFLG 0x001B No Event-trigger Flag Register
ETCLR 0x001C No Event-trigger Clear Register
ETFRC 0x001D No Event-trigger Force Register
• ETSEL—This selects which of the possible events will trigger an interrupt or start an ADC conversion
• ETPS—This programs the event prescaling options mentioned above.
• ETFLG—These are flag bits indicating status of the selected and prescaled events.
• ETCLR—These bits allow you to clear the flag bits in the ETFLG register via software.
• ETFRC—These bits allow software forcing of an event. Useful for debugging or s/w intervention.
A more detailed look at how the various register bits interact with the Interrupt and ADC start of
conversion logic are shown in Figure 3-42, Figure 3-43, and Figure 3-44.
Figure 3-42 shows the event-trigger's interrupt generation logic. The interrupt-period (ETPS[INTPRD]) bits
specify the number of events required to cause an interrupt pulse to be generated. The choices available
are:
• Do not generate an interrupt.
• Generate an interrupt on every event
• Generate an interrupt on every second event
• Generate an interrupt on every third event
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