AT89C52-12AC ATMEL Corporation, AT89C52-12AC Datasheet - Page 13

• Manufacturer Part Number: AT89C52-12AC
• Description: 8-Bit Microcontroller with 8K Bytes Flash
• Manufacturer: ATMEL Corporation

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.
Flash Programming Modes
Note:
Mode
Write Code Data
Read Code Data
Write Lock
Chip Erase
Read Signature Byte
(030H) = 1EH indicates manufactured by Atmel
(031H) = 52H indicates 89C52
(032H) = FFH indicates 12V programming
(032H) = 05H indicates 5V programming
1. Chip Erase requires a 10-ms PROG pulse.
Bit - 1
Bit - 2
Bit - 3
RST
H
H
H
H
H
H
H
PSEN
L
L
L
L
L
L
L
ALE/PROG
H
H
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.
(1)
EA/V
H/12V
H/12V
H/12V
H/12V
H/12V
H
H
PP
P2.6
H
H
H
H
L
L
L
P2.7
H
H
H
L
L
L
L
P3.6
H
H
H
H
L
L
L
P3.7
H
H
H
L
L
L
L
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