68HC705SP7 datasheet(177/230 Pages) FREESCALE

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Personality EPROM

PEPROM Erasing

MC68HC705JJ7/MC68HC705JP7 — Rev. 3.0

General Release Specification

Personality EPROM

Reading the PEPROM is easiest when each PEPROM column contains

one byte. Selecting a row 0 bit selects the first bit, and incrementing the

PEPROM bit select register (PEBSR) selects the next bit in row 1 from

the same column. Incrementing PEBSR seven more times selects the

remaining bits of the column and ends up selecting the bit in row 0 of the

next column, thereby setting the row 0 flag, PEPRZF.

NOTE:

A PEPROM byte that has been read can be transferred to the

personality EPROM bit select register (PEBSR) as a temporary storage

location such that subsequent reads of the PEBSR quickly yield that

PEPROM byte.

12.6 PEPROM Erasing

MCUs with windowed packages permit PEPROM erasure with

ultraviolet light. Erase the PEPROM by exposing it to 15 Ws/cm2 of

ultraviolet light with a wavelength of 2537 angstroms. Position the

ultraviolet light source 1 inch from the window. Do not use a shortwave

filter. The erased state of a PEPROM bit is a logic zero.

Freescale Semiconductor, Inc.

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68HC705SP7 Datasheet(PDF) 177 Page - Freescale Semiconductor, Inc