MC68HC908GZ8 Datasheet, PDF (49/344 Pages) Motorola, Inc – Microcontrollers

Data Sheet — MC68HC908GZ8
Section 4. Resets and Interrupts
4.1 Introduction
Resets and interrupts are responses to exceptional events during program
execution. A reset re-initializes the microcontroller (MCU) to its startup condition.
An interrupt vectors the program counter to a service routine.
4.2 Resets
A reset immediately returns the MCU to a known startup condition and begins
program execution from a user-defined memory location.
4.2.1 Effects
A reset:
• Immediately stops the operation of the instruction being executed
• Initializes certain control and status bits
• Loads the program counter with a user-defined reset vector address from
locations $FFFE and $FFFF
• Selects CGMXCLK divided by four as the bus clock
4.2.2 External Reset
A logic 0 applied to the RST pin for a time, t_RL, generates an external reset. An
external reset sets the PIN bit in the system integration module (SIM) reset status
register.
4.2.3 Internal Reset
Sources:
• Power-on reset (POR)
• Computer operating properly (COP)
• Low-power reset circuits
• Illegal opcode
• Illegal address
MC68HC908GZ8
Freescale Semiconductor
Resets and Interrupts
Data Sheet
49