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Functional description
39.5.11.10 FTM counter synchronization
The FTM counter synchronization is a mechanism that allows the FTM to restart the
PWM generation at a certain point in the PWM period. The channels outputs are forced
to their initial value, except for channels in Output Compare mode, and the FTM counter
is forced to its initial counting value defined by CNTIN register.
The following figure shows the FTM counter synchronization. Note that after the
synchronization event occurs, the channel (n) is set to its initial value and the channel (n
+1) is not set to its initial value due to a specific timing of this figure in which the
deadtime insertion prevents this channel output from transitioning to 1. If no deadtime
insertion is selected, then the channel (n+1) transitions to logical value 1 immediately
after the synchronization event occurs.
channel (n+1) match
FTM counter
channel (n) match
channel (n) output
(after deadtime
insertion)
channel (n+1) output
(after deadtime
insertion)
synchronization event
Figure 39-222. FTM counter synchronization
The FTM counter synchronization can be done by either the enhanced PWM
synchronization (SYNCMODE = 1) or the legacy PWM synchronization (SYNCMODE
= 0). However, the FTM counter must be synchronized only by the enhanced PWM
synchronization.
In the case of enhanced PWM synchronization, the FTM counter synchronization
depends on SWRSTCNT and HWRSTCNT bits according to the following flowchart.
KV4x Reference Manual, Rev. 2, 02/2015
Preliminary
986
Freescale Semiconductor, Inc.
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