3.2.4.3 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 3-9. Action-Qualifier Event Priority for Up-Down-Count Mode
Priority Level
Event If TBCTR is Incrementing
TBCTR = Zero up to TBCTR = TBPRD
Event If TBCTR is Decrementing
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 3-10. 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
defined as down and thus up-count events will never be taken.
Table 3-11. 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 3-12. Behavior if CMPA/CMPB is Greater than the Period
Counter Mode
Compare on Up-Count Event
CAU/CBU
Compare on Down-Count Event
CAD/CBD
Up-Count Mode
If CMPA/CMPB ≤ TBPRD period, then the event occurs
on a compare match (TBCTR=CMPA or CMPB).
Never occurs.
If CMPA/CMPB > TBPRD, then the event will not occur.
Enhanced Pulse Width Modulator (ePWM) Module
268
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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