MC68HC908QY4A_10 Datasheet, PDF (136/200 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Timer Interface Module (TIM)
Setting MS0B causes the contents of TSC1 to be ignored by the TIM and reverts TCH1 to
general-purpose I/O.
1 = Buffered output compare/PWM operation enabled
0 = Buffered output compare/PWM operation disabled
MSxA — Mode Select Bit A
When ELSxB:A ≠ 00, this read/write bit selects either input capture operation or unbuffered output
compare/PWM operation. See Table 14-2.
1 = Unbuffered output compare/PWM operation
0 = Input capture operation
When ELSxB:A = 00, this read/write bit selects the initial output level of the TCHx pin (see
Table 14-2).
1 = Initial output level low
0 = Initial output level high
NOTE
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).
ELSxB and ELSxA — Edge/Level Select Bits
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 an I/O port, and pin TCHx is
available as a general-purpose I/O pin. Table 14-2 shows how ELSxB and ELSxA work.
MSxB
X
X
0
0
0
0
0
0
0
1
1
1
MSxA
0
1
0
0
0
1
1
1
1
X
X
X
Table 14-2. Mode, Edge, and Level Selection
ELSxB
0
0
0
1
1
0
0
1
1
0
1
1
ELSxA
0
0
1
0
1
0
1
0
1
1
0
1
Mode
Output preset
Input capture
Output compare
or PWM
Buffered output
compare or
buffered PWM
Configuration
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
NOTE
After initially enabling a TIM channel register for input capture operation
and selecting the edge sensitivity, clear CHxF to ignore any erroneous
edge detection flags.
MC68HC908QYA/QTA Family Data Sheet, Rev. 3
136
Freescale Semiconductor