HCS08 datasheet(25/198 Pages) NXP

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MC9S08QD4 Series MCU Data Sheet, Rev. 6

Freescale Semiconductor

Chapter 3

Modes of Operation

3.1

Introduction

The operating modes of the MC9S08QD4 series are described in this chapter. Entry into each mode, exit

from each mode, and functionality while in each of the modes are described.

3.2

Features

•

Active background mode for code development

•

Wait mode:

— CPU shuts down to conserve power

— System clocks running

— Full voltage regulation maintained

•

Stop modes:

— CPU and bus clocks stopped

— Stop2 — Partial power down of internal circuits, RAM contents retained

— Stop3 — All internal circuits powered for fast recovery

3.3

Run Mode

This is the normal operating mode for the MC9S08QD4 series. 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.

3.4

Active Background Mode

The active background mode functions are managed through the background debug controller (BDC) in

the HCS08 core. The BDC 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 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

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