Motorola MC68HC908AB32 - IO Signals; TIMB Channel IO Pins; TIMB Clock Pin

Timer Interface Module B (TIMB)
I/O Signals
MC68HC908AB32 — Rev. 1.0 Technical Data
MOTOROLA Timer Interface Module B (TIMB) 209
12.9 I/O Signals
Port F shares four pins with the TIMB and port D shares one.
PTD4/TBCLK is an external clock input to the TIMB prescaler. The four
TIMB channel I/O pins are PTF4/TBCH0, PTF5/TBCH1, PTF2/TBCH2,
and PTF3/TBCH3.
12.9.1 TIMB Clock Pin
PTD4/TBCLK is an external clock input that can be the clock source for
the TIMB counter instead of the prescaled internal bus clock. Select the
PTD4/TBCLK input by writing logic 1s to the three prescaler select bits,
PS[2:0]. See 12.10.1 TIMB Status and Control Register. The minimum
TBCLK pulse width, TBCLK
LMIN
or TBCLK
HMIN
, is:
The maximum TBCLK frequency is:
bus frequency ÷ 2
PTD4/TBCLK is available as a general-purpose I/O pin when not used
as the TIMB clock input. When the PTD4/TBCLK pin is the TIMB clock
input, it is an input regardless of the state of the DDRD6 bit in data
direction register D.
12.9.2 TIMB Channel I/O Pins
Each channel I/O pin is programmable independently as an input
capture pin or an output compare pin. PTF2/TBCH2 and PTF5/TBCH1
can be configured as buffered output compare or buffered PWM pins.
1
bus frequency
------------------------------------- t
SU
+