mc9s08qg8 Freescale Semiconductor, Inc, mc9s08qg8 Datasheet - Page 31

• Manufacturer Part Number: mc9s08qg8
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 3
Modes of Operation
3.1
The operating modes of the MC9S08QG8/4 are described in this section. Entry into each mode, exit from
each mode, and functionality while in each mode are described.
3.2
3.3
Run is the normal operating mode for the MC9S08QG8/4. This mode is selected upon the MCU exiting
reset if the BKGD/MS pin is high. In this mode, the CPU executes code from internal memory with
execution beginning at the address fetched from memory at 0xFFFE:0xFFFF after reset.
3.4
The active background mode functions are managed through the background debug controller (BDC) in
the HCS08 core. The BDC, together with the on-chip debug module (DBG), provides the means for
analyzing MCU operation during software development.
Active background mode is entered in any of five ways:
Freescale Semiconductor
•
•
•
•
•
•
•
•
Active background mode for code development
Wait mode:
— CPU halts operation to conserve power
— System clocks running
— Full voltage regulation is maintained
Stop modes: CPU and bus clocks stopped
— Stop1: Full powerdown of internal circuits for maximum power savings
— Stop2: Partial powerdown of internal circuits; RAM contents retained
— Stop3: All internal circuits powered for fast recovery; RAM and register contents are retained
When the BKGD/MS pin is low during POR or immediately after issuing a background debug
force reset (see
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
Introduction
Features
Run Mode
Active Background Mode
5.8.3, “System Background Debug Force Reset Register
MC9S08QG8 and MC9S08QG4 Data Sheet, Rev. 1.01
(SBDFR)”)
31