MC68HC908RK2 Datasheet, PDF (19/158 Pages) Motorola, Inc – Microcontroller Unit

Pin Assignments
1.4.3 External Reset (RST)
A logic 0 on the RST pin forces the MCU to a known startup state. RST is bidirectional, allowing a reset
of the entire system. It is driven low when any internal reset source is asserted.
The RST pin contains an internal pullup resistor.
For additional information, see Chapter 10 System Integration Module (SIM).
1.4.4 External Interrupt Pin (IRQ)
IRQ is an asynchronous external interrupt pin.
The IRQ pin contains an internal pullup resistor.
1.4.5 Port A Input/Output Pins (PTA7, PTA6/KBD6–PTA1/KBD1, and PTA0)
Port A is an 8-bit special function port that shares its pins with the keyboard interrupt.
Six port A pins (PTA6–PTA1) can be programmed to serve as an external interrupt. Once enabled, that
pin will contain an internal pullup resistor.
All port A pins are high-current sink pins.
1.4.6 Port B Input/Output Pins (PTB5, PTB4/TCH1, PTB3/TCLK, PTB2/TCH0,
PTB1, and PTB0/MCLK)
Port B is a 6-bit, general-purpose, bidirectional I/O port, with some of its pins shared with the timer (TIM)
module.
MC68HC908RK2 Data Sheet, Rev. 5.1
Freescale Semiconductor
19