Programming interface, Flash programming modes, At89c52 – Rainbow Electronics AT89S52 User Manual
Page 14
AT89C52
14
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.
Note:
1. Chip Erase requires a 10 ms PROG pulse.
Flash Programming Modes
Mode
RST
PSEN
ALE/PROG
EA/V
PP
P2.6
P2.7
P3.6
P3.7
Write Code Data
H
L
H/12V
L
H
H
H
Read Code Data
H
L
H
H
L
L
H
H
Write Lock
Bit - 1
H
L
H/12V
H
H
H
H
Bit - 2
H
L
H/12V
H
H
L
L
Bit - 3
H
L
H/12V
H
L
H
L
Chip Erase
H
L
H/12V
H
L
L
L
Read Signature Byte
H
L
H
H
L
L
L
L
(1)