M68HC08 datasheet(35/172 Pages) FREESCALE

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MC68HC908JL3E Family Data Sheet, Rev. 3

Freescale Semiconductor

Chapter 3

Configuration Registers (CONFIG)

3.1 Introduction

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

enables or disables the following options:

•

Stop mode recovery time (32

× 2OSCOUT cycles or

4096

× 2OSCOUT cycles)

•STOP instruction

•

Computer operating properly module (COP)

•

COP reset period (COPRS), (213–24)

× 2OSCOUT or

(218–24)

× 2OSCOUT

•

Enable LVI circuit

•

Select LVI trip voltage

3.2 Functional Description

The configuration register is used in the initialization of various options. The configuration register can be

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

various options affect the operation of the MCU it is recommended that this register be written immediately

after reset. The configuration register is 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 3-1 and Figure 3-2.

3.3 Configuration Register 1 (CONFIG1)

COPRS — COP reset period selection bit

1 = COP reset cycle is (213 – 24)

× 2OSCOUT

0 = COP reset cycle is (218 – 24)

× 2OSCOUT

Address:

$001F

Bit 7

654321

Bit 0

Read:

COPRS

LVID

SSREC

STOP

COPD

Write:

Reset:

00000000

R= Reserved

Figure 3-1. Configuration Register 1 (CONFIG1)

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