Timer Pins; Parallel 1/0 Pins With Interrupt Capability - Motorola MC68302 User Manual

5.18 TIMER PINS
Each of these five pins can be used either as a dedicated timer function or
as a general-purpose port B 1/0 port pin. Note that the timers do not require
the use of external pins.
TIN1/PB3 - Timer 1 Input
This input is used as a timer clock source for timer 1, or as a trigger for
the timer 1 capture register. TIN1 may also be used as the external clock
source for any or all of the three SCC baud rate generators.
TOUT1/PB4 - Timer 1 Output
This output is used as an active-low pulse timeout, or an
event
overflow
output (toggle) from timer 1.
TIN2/PB5 - Timer 2 Input
This input can be used as a timer clock source for timer 2, or as a trigger
for the timer 2 capture register.
TOUT2/PB6 - Timer 2 Output
This output is used as an active-low pulse timeout, or as an event overflow
output (toggle) from timer 2.
WDOG/PB7 - Watchdog Output
This active-low, open-drain output indicates expiration of the watchdog
timer. WDOG is asserted for a period of 16 cycles and may be used to reset
the MC68302. It is not asserted by the on-chip hardware watchdog (see
the BERR signal description).
5.19 PARALLEL
1/0
PINS WITH INTERRUPT CAPABILITY
PB 11-PB8 -
Port B Parallel 1/0 pins
These four pins are always configured as a general-purpose parallel 1/0
ports with interrupt capability. Each of the pins can be configured either
as an input or an output. When configured as an input, each pin can gen-
erate a separate, maskable interrupt on a high-to-low transition.
MOTOROLA MC68302 USER'S MANUAL 5-17