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MC9S08GT16ACBE Datasheet, PDF (33/300 Pages) Freescale Semiconductor, Inc – Microcontrollers | |||
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Chapter 3
Modes of Operation
3.1 Introduction
The operating modes of the MC9S08GT16A/GT8A are described in this section. Entry into each mode,
exit from each mode, and functionality while in each of the modes are described.
3.1.1 Features
⢠Active background mode for code development
⢠Wait mode:
â CPU shuts down to conserve power
â System clocks running
â Full voltage regulation maintained
⢠Stop modes:
â Stop1 â Full power down of internal circuits for maximum power savings
â Stop2 â Partial power down of internal circuits, RAM contents retained
â Stop3 â All internal circuits powered for fast recovery
3.2 Run Mode
This is the normal operating mode for the MC9S08GT16A/GT8A. This mode is selected when the
BKGD/MS pin is high at the rising edge of reset. In this mode, the CPU executes code from internal
memory with execution beginning at the address fetched from memory at 0xFFFE:0xFFFF after reset.
3.3 Active Background Mode
The active background mode functions are managed through the background debug controller (BDC) in
the HCS08 core. The BDC, together with the on-chip ICE debug module (DBG), provide the means for
analyzing MCU operation during software development.
Active background mode is entered in any of ï¬ve ways:
⢠When the BKGD/MS pin is low at the rising edge of reset
⢠When a BACKGROUND command is received through the BKGD pin
⢠When a BGND instruction is executed
⢠When encountering a BDC breakpoint
⢠When encountering a DBG breakpoint
MC9S08GT16A/GT8A Data Sheet, Rev. 1
Freescale Semiconductor
33
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