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Chapter 27 Timers
MPC5606BK Microcontroller Reference Manual, Rev. 2
696
Freescale Semiconductor
Register A2 defines the generation of a trigger event within the PWM period. A2 should be configured
with any value within the range of the selected time base. Otherwise, no trigger will be generated. A match
on the comparator will generate the FLAG signal but it has no effect on the PWM output signal generation.
The typical setup to obtain a trigger with FLAG is to enable DMA and to drive the channel’s ipd_done
input high.
A2 is not buffered and therefore its update is immediate. If the channel is running when a change is made,
this could cause either the loss of one trigger event or the generation of two trigger events within the same
period. Register A2 can be accessed by reading or writing the eMIOS UC Alternate A Register
(EMIOSALTA) at UC[n] base a0x14.
FLAG signal is set only at match on the comparator with A2. A match on the comparator with A1 or B1
or B2 has no effect on FLAG.
At any time, the FORCMA and FORCMB bits allow the software to force the output flip-flop to the level
corresponding to a match on A or B respectively. Any FORCMA and/or FORCMB has priority over any
simultaneous match regarding to output pin transitions. Note that the load of B2 content on B1 register at
an A match is not inhibited due to a simultaneous FORCMA/FORCMB assertion. If both FORCMA and
FORCMB are asserted simultaneously the output pin goes to the opposite of EDPOL value such as if A1
and B1 registers had the same value. FORCMA assertion causes the transfer from register B2 to B1 such
as a regular A match, regardless of FORCMB assertion.
If subsequent matches occur on comparators A1 and B, the PWM pulses continue to be generated,
regardless of the state of the FLAG bit.
At OPWMT mode entry the output flip-flop is set to the complement of the EDPOL bit in the EMIOSC[n]
register.
In order to achieve 0% duty cycle both registers A1 and B must be set to the same value. When a
simultaneous match on comparators A and B occur, the output flip-flop is set at every period to the
complement value of EDPOL.
In order to achieve 100% duty cycle the register B1 must be set to a value greater than maximum value of
the selected time base. As a consequence, if 100% duty cycle must be implemented, the maximum counter
value for the time base is 0xFFFE for a 16-bit counter. When a match on comparator A1 occurs the output
flip-flop is set at every period to the value of EDPOL bit. The transfer from register B2 to B1 is still
triggered by the match at comparator A.
shows the Unified Channel running in OPWMT mode with Trigger Event Generation and
duty cycle update on next period update.
Summary of Contents for MPC5605BK
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Page 20: ...MPC5606BK Microcontroller Reference Manual Rev 2 20 Freescale Semiconductor...
Page 103: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 103 Clocks and power...
Page 645: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 643 Timers...
Page 715: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 713 ADC system...
Page 787: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 787 Memory...
Page 893: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 893 Integrity...
Page 943: ...MPC5606BK Microcontroller Reference Manual Rev 2 Freescale Semiconductor 943 Debug...