mcf51ac256a Freescale Semiconductor, Inc, mcf51ac256a Datasheet - Page 232

• Manufacturer Part Number: mcf51ac256a
• Description: Mcf51ac Flexis
• Manufacturer: Freescale Semiconductor, Inc

FlexTimer Module (FTMV1)
11.4.3.2
Up-down counting is selected when (FTMEN = 0) and (CPWMS = 1).
FTMxCNTINH:FTMxCNTINL defines the starting value of the count and FTMxMODH:FTMxMODL
the final value of the count
FTM counter, and the counter incremented until the value of FTMxMODH:FTMxMODL is reached, at
which point the counter is decremented until it returns to the value of FTMxCNTINH:FTMxCNTINL and
the up-down counting restarts.
The FTM period when using up-down counting is 2 x (FTMxMODH:FTMxMODL -
FTMxCNTINH:FTMxCNTINL) x period of the FTM counter clock.
The TOF bit is set when the FTM counter changes from FTMxMODH:FTMxMODL to
(FTMxMODH:FTMxMODL - 1).
If (FTMxCNTINH:FTMxCNTINL = 0x0000), the FTM counting is equivalent to TPM up-down counting
(that is, up-down and unsigned counting)
11-32
Figure 11-29. Example of up counting when the value of FTMxCNTINH:FTMxCNTINL registers is greater
FTM counting is up (CPWMS = 0)
FTMxMODH:L = 0x0005
FTMxCNTINH:L = 0x0015
FTM counter
TOF bit
load of FTMxCNTINH:L
Up-down counting
0x0005 0x0015 0x0016 ... 0xFFFE 0xFFFF 0x0000 0x0001 0x0002 0x0003
MCF51AC256 ColdFire Integrated Microcontroller Reference Manual, Rev. 5
(Figure
than the value of FTMxMODH:FTMxMODL registers
11-30). The value of FTMxCNTINH:FTMxCNTINL is loaded into the
(Figure
11-30).
0x0004 0x0005 0x0015 0x0016 ...
load of FTMxCNTINH:L
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