68HC705SP7 datasheet(184/230 Pages) FREESCALE

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EPROM/OTPROM

General Release Specification

MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0

EPROM/OTPROM

13.3.3 EPROM Security Bit (EPMSEC)

An EPROM programmable bit is provided at the location of the COP

watchdog register at $1FF0 as shown in Figure 13-3. This bit allows

control of access to the EPROM array. Any accesses of the EPROM

locations will return undefined results when the EPMSEC bit is set. Refer

to 13.4.2 EPMSEC Programming for programming instructions.

EPMSEC — EPROM Security1

This EPROM write-only bit enables the access to the EPROM array.

1 = Access to the EPROM array in non-user modes is denied

0 = Access to the EPROM array in non-user modes is enabled

1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or

copying the EPROM/OTPROM difficult for unauthorized users.

13.4 EPROM Programming

A programming board is available from Motorola to download to the on-

chip EPROM/OTPROM using the factory-provided programming

software. Factory-provided software for programming the EPROM is

available through the Motorola Freeware Bulletin Board Service (BBS).

The number is (512) 891-FREE. After making the connection, type bbs

in lowercase letters and press the return key to start the BBS software.

The programming software copies to the 6144-byte space located at

EPROM addresses $0700–$1EFF and to the 16-byte space at

$1FF0

Bit 7

654321

Bit 0

Read:

EPMSEC

OPT

Write:

COPC

Reset:

Unaffected by Reset

Erased:

———————

= Unimplemented

Figure 13-3. EPROM Security in COP Register (COP)

Freescale Semiconductor, Inc.

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