P89C668 Philips Semiconductors, P89C668 Datasheet - Page 38

• Manufacturer Part Number: P89C668
• Description: 80C51 8-bit Flash microcontroller family 64KB ISP FLASH with 8KB RAM
• Manufacturer: Philips Semiconductors

Philips Semiconductors
EXPLANATION OF THE AC SYMBOLS
Each timing symbol has five characters. The first character is always
‘t’ (= time). The other characters, depending on their positions,
indicate the name of a signal or the logical status of that signal. The
designations are:
A – Address
C – Clock
D – Input data
H – Logic level high
I – Instruction (program memory contents)
L – Logic level low, or ALE
2001 Jul 27
PORT 0
PORT 2
80C51 8-bit Flash microcontroller family
64KB ISP Flash with 8KB RAM
PSEN
ALE
RD
PORT 0
PORT 2
PSEN
ALE
t
AVLL
FROM RI OR DPL
A0–A7
t
LLAX
t
t
AVWL
LHLL
t
t
LLWL
AVLL
A0–A7
Figure 30. External Program Memory Read Cycle
t
t
AVDV
P2.0–P2.7 OR A8–A15 FROM DPF
RLAZ
Figure 31. External Data Memory Read Cycle
t
LLDV
t
t
t
AVIV
LLAX
LLPL
t
LLIV
t
t
PLIV
RLDV
A0–A15
t
PLAZ
t
PLPH
t
RLRH
t
PXIX
INSTR IN
38
t
RHDX
DATA IN
P – PSEN
Q – Output data
R – RD signal
t – Time
V – Valid
W – WR signal
X – No longer a valid logic level
Z – Float
Examples: t
t
PXIZ
t
RHDZ
t
t
AVLL
WHLH
LLPL
= Time for address valid to ALE low.
=Time for ALE low to PSEN low.
A0–A7
A0–A7 FROM PCL
A0–A15 FROM PCH
A8–A15
P89C668
Preliminary data
SU00006
INSTR IN
SU00025