P87C554 NXP Semiconductors, P87C554 Datasheet - Page 69

• Manufacturer Part Number: P87C554
• Description: The P87C554 Single-Chip 8-Bit Microcontroller is manufactured inan advanced CMOS process and is a derivative of the 80C51microcontroller family
• Manufacturer: NXP 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
P – PSEN
2002 Mar 25
PORT 0
PORT 2
80C51 8-bit microcontroller – 12 clock operation
16K/512 OTP/RAM, 8 channel 10-bit A/D, I
capture/compare, high I/O
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 49. External Program Memory Read Cycle
t
t
P2.0–P2.7 OR A8–A15 FROM DPH
AVDV
RLAZ
Figure 50. External Data Memory Read Cycle
t
LLDV
t
t
t
AVIV
LLAX
LLPL
t
LLIV
t
t
PLIV
RLDV
A0–A15
t
2
PLAZ
t
PLPH
C, PWM,
t
RLRH
t
PXIX
INSTR IN
67
t
RHDX
DATA IN
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
WHLH
AVLL
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
SU00006
P87C554
INSTR IN
Product data
SU00007