software trigger event occurred; see
Boundary cycle and loading points
figure. If (PWMSYNC = 0) and (REINIT = 1) then SWSYNC bit is cleared when the
software trigger event occurs.
If SYNCMODE = 1 then the SWSYNC bit is also cleared by FTM according to the
SWRSTCNT bit. If SWRSTCNT = 0 then SWSYNC bit is cleared at the next selected
loading point after that the software trigger event occurred; see the following figure. If
SWRSTCNT = 1 then SWSYNC bit is cleared when the software trigger event occurs.
system clock
selected loading point
PWM synchronization
SWSYNC bit
software trigger event
write 1 to SWSYNC bit
Figure 38-207. Software trigger event
38.4.11.3 Boundary cycle and loading points
The boundary cycle definition is important for the loading points for the registers MOD,
CNTIN, and C(n)V.
In
mode, the boundary cycle is defined as when the counter wraps to its
mode, then the boundary cycle is defined
as when the counter turns from down to up counting and when from up to down counting.
The following figure shows the boundary cycles and the loading points for the registers.
In the Up Counting mode, the loading points are enabled if one of CNTMIN or CTMAX
bits are 1. In the Up-Down Counting mode, the loading points are selected by CNTMIN
and CNTMAX bits, as indicated in the figure. These loading points are safe places for
register updates thus allowing a smooth transitions in PWM waveform generation.
For both counting modes, if neither CNTMIN nor CNTMAX are 1, then the boundary
cycles are not used as loading points for registers updates. See the register
synchronization descriptions in the following sections for details.
Chapter 38 FlexTimer Module (FTM)
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc.
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