MC68HC908QL4 Datasheet, PDF (184/226 Pages) Motorola, Inc – Microcontrollers

Timer Interface Module (TIM)
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 15-2.
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 15-2).
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).
Table 15-2. Mode, Edge, and Level Selection
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
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
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 15-2 shows how ELSxB and ELSxA work.
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.
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 counter overflows. When channel x is an input capture channel, TOVx has no effect.
1 = Channel x pin toggles on TIM counter overflow.
0 = Channel x pin does not toggle on TIM counter overflow.
NOTE
When TOVx is set, a counter overflow takes precedence over a channel x
output compare if both occur at the same time.
MC68HC908QL4 Data Sheet, Rev. 7
184
Freescale Semiconductor