mc9s08gt16a Freescale Semiconductor, Inc, mc9s08gt16a Datasheet - Page 63

• Manufacturer Part Number: mc9s08gt16a
• Description: Hcs08 Microcontrollers 8-bit Microcontroller Family
• Manufacturer: Freescale Semiconductor, Inc

Chapter 5
Resets, Interrupts, and System Configuration
5.1
This section discusses basic reset and interrupt mechanisms and the various sources of reset and interrupts
in the MC9S08GT16A/GT8A. Some interrupt sources from peripheral modules are discussed in greater
detail within other sections of this data manual. This section 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.
5.1.1
Reset and interrupt features include:
5.2
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 MC9S08GT16A/GT8A has eight sources for reset:
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 with enable
— 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
MCU Reset
Features
MC9S08GT16A/GT8A Data Sheet, Rev. 1
Table
5-1)
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