MC908QT4MPE datasheet(53/184 Pages) FREESCALE

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MC68HC908QY/QT Family Data Sheet, Rev. 5

Freescale Semiconductor

Chapter 5

Configuration Register (CONFIG)

5.1 Introduction

This section describes the configuration registers (CONFIG1 and CONFIG2). The configuration registers

enable or disable the following options:

•

Stop mode recovery time (32

× BUSCLKX4 cycles or

4096

× BUSCLKX4 cycles)

•STOP instruction

•

Computer operating properly module (COP)

•

COP reset period (COPRS): 8176

× BUSCLKX4 or 262,128 × BUSCLKX4

•

Low-voltage inhibit (LVI) enable and trip voltage selection

•

OSC option selection

•IRQ pin

•RST pin

•

Auto wakeup timeout period

5.2 Functional Description

The configuration registers are used in the initialization of various options. The configuration registers can

be written once after each reset. Most of the configuration register bits are cleared during reset. Since the

various options affect the operation of the microcontroller unit (MCU) it is recommended that this register

be written immediately after reset. The configuration registers are located at $001E and $001F, and may

be read at anytime.

NOTE

The CONFIG registers are one-time writable by the user after each reset.

Upon a reset, the CONFIG registers default to predetermined settings as

shown in Figure 5-1 and Figure 5-2.

Address: $001E

Bit 7

Bit 0

Read:

IRQPUD

IRQEN

OSCOPT1

OSCOPT0

RSTEN

Write:

Reset:

000

POR:

000

= Reserved

U = Unaffected

Figure 5-1. Configuration Register 2 (CONFIG2)

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