Freescale Semiconductor MC68HC908MR32 - Manual (Page 231)

I/O Registers
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 231
TOVx — Toggle-On-Overflow Bit
When channel x is an output compare channel, this read/write bit controls the behavior of the channel
x output when the TIMA counter overflows. When channel x is an input capture channel, TOVx has no
effect. Reset clears the TOVx bit.
1 = Channel x pin toggles on TIMA counter overflow.
0 = Channel x pin does not toggle on TIMA counter overflow.
NOTE
When TOVx is set, a TIMA counter overflow takes precedence over a
channel x output compare if both occur at the same time.
CHxMAX — Channel x Maximum Duty Cycle Bit
When the TOVx is 1 and clear output on compare is selected, setting the CHxMAX bit forces the duty
cycle of buffered and unbuffered PWM signals to 100 percent. As
Figure 16-9 shows, CHxMAX bit
takes effect in the cycle after it is set or cleared. The output stays at 100 percent duty cycle level until
the cycle after CHxMAX is cleared.
Figure 16-9. CHxMAX Latency
Table 16-2. Mode, Edge, and Level Selection
MSxB:MSxA ELSxB:ELSxA Mode Configuration
X0 00
Output preset
Pin under port control; initialize timer output level high
X1 00 Pin under port control; initialize timer output level low
00 01
Input capture
Capture on rising edge only
00 10 Capture on falling edge only
00 11 Capture on rising or falling edge
01 00
Output
compare
or PWM
Software compare only
01 01 Toggle output on compare
01 10 Clear output on compare
01 11 Set output on compare
1X 01
Buffered
output compare
or buffered PWM
Toggle output on compare
1X 10 Clear output on compare
1X 11 Set output on compare
OUTPUT
OVERFLOW
PTEx/TCHx
PERIOD
CHxMAX
OVERFLOW OVERFLOW OVERFLOW OVERFLOW
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
OUTPUT
COMPARE
TOVx