mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 43

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 4
Resets and Interrupts
4.1 Introduction
Resets and interrupts are responses to exceptional events during program execution. A reset re-initializes
the 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:
4.2.2 External Reset
A logic 0 applied to the RST pin for a time, t
PIN bit in the SIM reset status register.
4.2.3 Internal Reset
Sources:
All internal reset sources pull the RST pin low for 32 CGMXCLK cycles to allow resetting of external
devices. The MCU is held in reset for an additional 32 CGMXCLK cycles after releasing the RST pin.
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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, $FEFE and $FFFF in monitor mode
Selects CGMXCLK divided by four as the bus clock
Power-on reset (POR)
Computer operating properly (COP)
Low-power reset circuits
Illegal opcode
Illegal address
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
IRL
, generates an external reset. An external reset sets the
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