mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 243

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

ELSxB and ELSxA — Edge/Level Select Bits
TOVx — Toggle On Overflow Bit
Freescale Semiconductor
When ELSxB:A = 00, this read/write bit selects the initial output level of the TCHx pin. See
Reset clears the MSxA bit.
When channel x is an input capture channel, these read/write bits control the active edge-sensing logic
on channel x.
When channel x is an output compare channel, ELSxB and ELSxA control the channel x output
behavior when an output compare occurs.
When ELSxB and ELSxA are both clear, channel x is not connected to port D, and pin PTDx/TCHx is
available as a general-purpose I/O pin.
the ELSxB and ELSxA bits.
When channel x is an output compare channel, this read/write bit controls the behavior of the channel
x output when the TIM counter overflows. When channel x is an input capture channel, TOVx has no
effect. Reset clears the TOVx bit.
1 = Initial output level low
0 = Initial output level high
1 = Channel x pin toggles on TIM counter overflow.
0 = Channel x pin does not toggle on TIM counter overflow.
MSxB
X
X
0
0
0
0
0
0
0
1
1
1
Before changing a channel function by writing to the MSxB or MSxA bit, set
the TSTOP and TRST bits in the TIM status and control register (TSC).
Before enabling a TIM channel register for input capture operation, make
sure that the PTD/TCHx pin is stable for at least two bus clocks.
When TOVx is set, a TIM counter overflow takes precedence over a
channel x output compare if both occur at the same time.
MSxA
X
X
X
0
1
0
0
0
1
1
1
1
ELSxB
0
0
0
1
1
0
0
1
1
0
1
1
Table 22-3. Mode, Edge, and Level Selection
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
ELSxA
0
0
1
0
1
0
1
0
1
1
0
1
Table 22-3
Output compare
Buffered output
buffered PWM
Output preset
Input capture
compare or
or PWM
Mode
NOTE
NOTE
NOTE
shows how ELSxB and ELSxA work. Reset clears
Pin under port control; initial output level high
Pin under port control; initial output level low
Capture on rising edge only
Capture on falling edge only
Capture on rising or falling edge
Software compare only
Toggle output on compare
Clear output on compare
Set output on compare
Toggle output on compare
Clear output on compare
Set output on compare
Configuration
I/O Registers
Table
22-3.
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