mcf51jf128 Freescale Semiconductor, Inc, mcf51jf128 Datasheet - Page 851

• Manufacturer Part Number: mcf51jf128
• Description: Mcf51jf128 Reference Manual
• Manufacturer: Freescale Semiconductor, Inc

If (ELSnB:ELSnA = 1:0), then the channel (n) output is forced high at the channel (n)
match (FTM counter = CnVH:L) when counting down, and it is forced low at the channel
(n) match when counting up (see the following figure).
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).
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 (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.
Freescale Semiconductor, Inc.
MODH:L = 0x0008
CnVH:L = 0x0005
MODH:L = 0x0008
CnVH:L = 0x0005
channel (n) output
channel (n) output
CHnF bit
CNTH:L
CNTH:L
CHnF bit
TOF bit
TOF bit
...
...
Figure 37-161. CPWM Signal with ELSnB:ELSnA = X:1
Figure 37-160. CPWM Signal with ELSnB:ELSnA = 1:0
previous value
previous value
7
7
overflow
counter
overflow
counter
8
8
MCF51JF128 Reference Manual, Rev. 2, 03/2011
7
7
channel (n) match in
channel (n) match in
down counting
down counting
6
6
5
5
4
4
3
3
Preliminary
2
2
1
1
0
0
1
1
2
2
channel (n) match in
channel (n) match in
3
3
up counting
up counting
4
4
5
5
6
6
Chapter 37 FlexTimer (FTM)
7
7
overflow
counter
8
overflow
counter
8
channel (n) match in
channel (n) match in
7
7
down counting
down counting
6
6
5
5
...
...
851