p89v51rb2 NXP Semiconductors, p89v51rb2 Datasheet - Page 66

• Manufacturer Part Number: p89v51rb2
• Description: 8-bit 80c51 5 V Low Power 16/32/64 Kb Flash Microcontroller With 1 Kb Ram
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89V51RB2_RC2_RD2_4
Product data sheet
Fig 31. External program memory read cycle
PSEN
port 0
port 2
ALE
9.1 Explanation of symbols
Each timing symbol has 5 characters. The first character is always a ‘T’ (stands for time).
The other characters, depending on their positions, stand for the name of a signal or the
logical status of that signal. The following is a list of all the characters and what they stand
for.
A — Address
C — Clock
D — Input data
H — Logic level HIGH
I — Instruction (program memory contents)
L — Logic level LOW or ALE
P — PSEN
Q — Output data
R — RD signal
T — Time
V — Valid
W — WR signal
X — No longer a valid logic level
Z — High impedance (Float)
Example:
t
t
AVLL
LLPL
t
= Address valid to ALE LOW time
= ALE LOW to PSEN LOW time
AVLL
t
LHLL
t
LLAX
A0 to A7
t
LLPL
t AVIV
Rev. 04 — 1 May 2007
A8 to A15
t
PLAZ
t
t
PLIV
LLIV
INSTR IN
t
PXIX
t
PXIZ
P89V51RB2/RC2/RD2
t
PLPH
8-bit microcontrollers with 80C51 core
t
PXAV
A0 to A7
A8 to A15
002aaa548
© NXP B.V. 2007. All rights reserved.
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