![Texas Instruments TMS320x2823x Reference Manual Download Page 41](http://html1.mh-extra.com/html/texas-instruments/tms320x2823x/tms320x2823x_reference-manual_1095205041.webp)
www.ti.com
ePWM Submodules
2.4.3
Action-Qualifier Event Priority
It is possible for the ePWM action qualifier to receive more than one event at the same time. In this case
events are assigned a priority by the hardware. The general rule is events occurring later in time have a
higher priority and software forced events always have the highest priority. The event priority levels for
up-down-count mode are shown in
. A priority level of 1 is the highest priority and level 7 is the
lowest. The priority changes slightly depending on the direction of TBCTR.
Table 9. Action-Qualifier Event Priority for Up-Down-Count Mode
Priority Level
Event If TBCTR is Incrementing
Event If TBCTR is Decrementing
TBCTR = Zero up to TBCTR = TBPRD
TBCTR = TBPRD down to TBCTR = 1
1 (Highest)
Software forced event
Software forced event
2
Counter equals CMPB on up-count (CBU)
Counter equals CMPB on down-count (CBD)
3
Counter equals CMPA on up-count (CAU)
Counter equals CMPA on down-count (CAD)
4
Counter equals zero
Counter equals period (TBPRD)
5
Counter equals CMPB on down-count (CBD)
Counter equals CMPB on up-count (CBU)
6 (Lowest)
Counter equals CMPA on down-count (CAD)
Counter equals CMPA on up-count (CBU)
shows the action-qualifier priority for up-count mode. In this case, the counter direction is always
defined as up and thus down-count events will never be taken.
Table 10. Action-Qualifier Event Priority for Up-Count Mode
Priority Level
Event
1 (Highest)
Software forced event
2
Counter equal to period (TBPRD)
3
Counter equal to CMPB on up-count (CBU)
4
Counter equal to CMPA on up-count (CAU)
5 (Lowest)
Counter equal to Zero
shows the action-qualifier priority for down-count mode. In this case, the counter direction is
always defined as down and thus up-count events will never be taken.
Table 11. Action-Qualifier Event Priority for Down-Count Mode
Priority Level
Event
1 (Highest)
Software forced event
2
Counter equal to Zero
3
Counter equal to CMPB on down-count (CBD)
4
Counter equal to CMPA on down-count (CAD)
5 (Lowest)
Counter equal to period (TBPRD)
It is possible to set the compare value greater than the period. In this case the action will take place as
shown in
Table 12. Behavior if CMPA/CMPB is Greater than the Period
Counter Mode
Compare on Up-Count Event
Compare on Down-Count Event
CAD/CBD
CAD/CBD
Up-Count Mode
If CMPA/CMPB
≤
TBPRD period, then the event
Never occurs.
occurs on a compare match (TBCTR=CMPA or
CMPB).
If CMPA/CMPB > TBPRD, then the event will not
occur.
Down-Count Mode
Never occurs.
If CMPA/CMPB < TBPRD, the event will occur on a
compare match (TBCTR=CMPA or CMPB).
If CMPA/CMPB
≥
TBPRD, the event will occur on a
period match (TBCTR=TBPRD).
41
SPRUG04A – October 2008 – Revised July 2009
TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module
© 2008–2009, Texas Instruments Incorporated