TOF bit
...
7
8
8
7
7
7
6
6
6
5
5
5
4
4
3
3
2
2
1
0
1
...
previous value
CNTH:L
channel (n) output
counter
overflow
channel (n) match in
down counting
channel (n) match in
up counting
channel (n) match in
down counting
counter
overflow
CHnF bit
MODH:L = 0x0008
CnVH:L = 0x0005
Figure 12-203. CPWM signal with ELSnB:ELSnA = 1:0
If (ELSnB:ELSnA = X:1), then the channel (n) output is forced low at the channel (n)
match (FTM counter = CnVH:L) when counting down, and it is forced high at the
channel (n) match when counting up; see the following figure.
TOF bit
...
7
8
8
7
7
7
6
6
6
5
5
5
4
4
3
3
2
2
1
0
1
...
previous value
CNTH:L
channel (n) output
counter
overflow
channel (n) match in
down counting
channel (n) match in
up counting
channel (n) match in
down counting
counter
overflow
CHnF bit
MODH:L = 0x0008
CnVH:L = 0x0005
Figure 12-204. CPWM signal with ELSnB:ELSnA = X:1
If (CnVH:L = 0x0000) or (CnVH:L is a negative value, that is, CnVH[7] = 1) then the
channel (n) output is a 0% duty cycle CPWM signal and CHnF bit is not set even when
there is the channel (n) match.
If (CnVH:L is a positive value, that is, CnVH[7] = 0), (CnVH:L ≥ MODH:L), and
(MODH:L ≠ 0x0000), then the channel (n) output is a 100% duty cycle CPWM signal
and CHnF bit is not set even when there is the channel (n) match. This implies that the
usable range of periods set by MODH:L is 0x0001 through 0x7FFE, or 0x7FFF if you do
not need to generate a 100% duty cycle CPWM signal. This is not a significant limitation
because the resulting period is much longer than required for normal applications.
The CPWM mode must not be used when the FTM counter is a free running counter.
Note
• CPWM mode is available only with (CNTINH:L =
0x0000).
• CPWM mode with (CNTINH:L ≠ 0x0000) is not
recommended and its results are not guaranteed.
Chapter 12 FlexTimer Module (FTM)
MC9S08PT60 Reference Manual, Rev. 4, 08/2014
Freescale Semiconductor, Inc.
349
Содержание MC9S08PT60
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Страница 200: ...Port data registers MC9S08PT60 Reference Manual Rev 4 08 2014 200 Freescale Semiconductor Inc...
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Страница 396: ...FTM Interrupts MC9S08PT60 Reference Manual Rev 4 08 2014 396 Freescale Semiconductor Inc...
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