AT89C55 Datasheet, PDF (15/24 Pages) ATMEL Corporation – 8-Bit Microcontroller with 20K Bytes Flash

AT89C55
Flash Programming Modes
Mode
RST PSEN
Write Code Data
H
L
Read Code Data
H
L
Write Lock
Bit-1
H
L
Bit-2
H
L
Bit-3
H
L
Chip Erase
H
L
Read Signature Byte
H
L
Note: 1. Chip Erase requires a 10-ms PROG pulse.
ALE/PROG
H
(1)
H
EA/V_PP
H/12V
H
H/12V
H/12V
H/12V
H/12V
H
P2.6
L
L
H
P2.7
H
L
H
P3.6
H
H
H
P3.7
H
H
H
H
H
L
L
H
L
H
L
H
L
L
L
L
L
L
L
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