AT89 datasheet(13/22 Pages) ATMEL

13 / 22 page

AT89C52

4-73

Chip Erase:

The entire Flash array is erased electrically

by using the proper combination of control signals and by

holding ALE/PROG low for 10 ms. The code array is written

with all 1s. The chip erase operation must be executed

before the code memory can be reprogrammed.

Reading the Signature Bytes: The signature bytes are

read by the same procedure as a normal verification of

locations 030H, 031H, and 032H, except that P3.6 and

P3.7 must be pulled to a logic low. The values returned are

as follows.

(030H) = 1EH indicates manufactured by Atmel

(031H) = 52H indicates 89C52

(032H) = FFH indicates 12V programming

(032H) = 05H indicates 5V programming

Programming Interface

Every code byte in the Flash array can be written, and the

entire array can be erased, by using the appropriate combi-

nation of control signals. The write operation cycle is self-

timed and once initiated, will automatically time itself to

completion.

All major programming vendors offer worldwide support for

the Atmel microcontroller series. Please contact your local

programming vendor for the appropriate software revision.

Flash Programming Modes

Note:

1. Chip Erase requires a 10-ms PROG pulse.

Mode

RST

PSEN

ALE/PROG

EA/VPP

P2.6

P2.7

P3.6

P3.7

Write Code Data

H/12V

Read Code Data

Write Lock

Bit - 1

H/12V

Bit - 2

H/12V

Bit - 3

H/12V

Chip Erase

H/12V

Read Signature Byte

(1)

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