MC9S08AW8A FREESCALE [Freescale Semiconductor, Inc], MC9S08AW8A Datasheet - Page 63

• Manufacturer Part Number: MC9S08AW8A
• Description: 8-Bit HCS08 Central Processor Unit (CPU)
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Chapter 5
Resets, Interrupts, and System Configuration
5.1
This chapter discusses basic reset and interrupt mechanisms and the various sources of reset and interrupts
in the MC9S08AC16 Series. Some interrupt sources from peripheral modules are discussed in greater
detail within other chapters of this data manual. This chapter gathers basic information about all reset and
interrupt sources in one place for easy reference. A few reset and interrupt sources, including the computer
operating properly (COP) watchdog and real-time interrupt (RTI), are not part of on-chip peripheral
systems with their own sections but are part of the system control logic.
5.2
Reset and interrupt features include:
5.3
Resetting the MCU provides a way to start processing from a known set of initial conditions. During reset,
most control and status registers are forced to initial values and the program counter is loaded from the
reset vector (0xFFFE:0xFFFF). On-chip peripheral modules are disabled and I/O pins are initially
configured as general-purpose high-impedance inputs with pullup devices disabled. The I bit in the
condition code register (CCR) is set to block maskable interrupts so the user program has a chance to
initialize the stack pointer (SP) and system control settings. SP is forced to 0x00FF at reset.
The following sources of reset are available on the MC9S08AC16 Series:
Freescale Semiconductor
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Multiple sources of reset for flexible system configuration and reliable operation:
— Power-on detection (POR)
— Low voltage detection (LVD) with enable
— External RESET pin
— COP watchdog with enable and two timeout choices
— Illegal opcode
— Illegal address
— Serial command from a background debug host
Reset status register (SRS) to indicate source of most recent reset
Separate interrupt vectors for each module (reduces polling overhead) (see
Power-on reset (POR)
Low-voltage detect (LVD)
Introduction
Features
MCU Reset
MC9S08AC16 Series Data Sheet, Rev. 6
Table
5-11)
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