NXP Semiconductors K22F series - Page 951

FTM counter
...
...
FTM counting is up
TOF bit
0x0005 0x0015 0x0016 0xFFFE 0xFFFF
0x0000
0x0001 0x0002
0x0003
0x0004
0x0005
0x0015
0x0016
MOD = 0x0005
CNTIN = 0x0015
set TOF bit set TOF bit
load of CNTIN
load of CNTIN
...
Figure 39-6. Example of up counting when the value of CNTIN is greater than the value
of MOD
39.4.3.2 Up-down counting
Up-down counting is selected when:
• QUADEN = 0, and
• CPWMS = 1
CNTIN defines the starting value of the count and MOD defines the final value of the
count. The value of CNTIN is loaded into the FTM counter, and the counter increments
until the value of MOD is reached, at which point the counter is decremented until it
returns to the value of CNTIN and the up-down counting restarts.
The FTM period when using up-down counting is 2 × (MOD – CNTIN) × period of the
FTM counter clock.
The TOF bit is set when the FTM counter changes from MOD to (MOD – 1).
If (CNTIN = 0x0000), the FTM counting is equivalent to TPM up-down counting, that is,
up-down and unsigned counting. See the following figure.
Chapter 39 FlexTimer Module (FTM)
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
NXP Semiconductors 951