MC9S08JM16 Datasheet, PDF (31/386 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 3
Modes of Operation
3.1 Introduction
The operating modes of the MC9S08JM16 series are described in this chapter. Entry into each mode, exit
from each mode, and functionality while in each mode are described.
3.2 Features
• Active background mode for code development
• Wait mode:
— CPU halts operation to conserve power
— System clocks continue to run
— Full voltage regulation is maintained
• Stop modes: CPU and bus clocks stopped
— Stop2: Partial power down of internal circuits; RAM and USB RAM contents retained
— Stop3: All internal circuits powered for fast recovery; RAM, USB RAM, and register contents
are retained
3.3 Run Mode
Run is the normal operating mode for the MC9S08JM16 series. 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 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 in-circuit emulator (ICE) debug module (DBG),
provides the means for analyzing MCU operation during software development.
Active background mode is entered in any of five ways:
• When the BKGD/MS pin is low during POR or immediately after issuing a background debug
force reset (see Section 5.7.3, “System Background Debug Force Reset Register (SBDFR)”)
• 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
MC9S08JM16 Series Data Sheet, Rev. 2
Freescale Semiconductor
31