Philips Semiconductors Product specification
80C31/80C32
80C51 8-bit microcontroller family
128/256 byte RAM ROMless low voltage (2.7V–5.5V),
low power, high speed (33 MHz)
2000 Aug 07
25
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
Q – Output data
R–RD
signal
t – Time
V – Valid
W– WR
signal
X – No longer a valid logic level
Z – Float
Examples: t
AVLL
= Time for address valid to ALE low.
t
LLPL
=Time for ALE low to PSEN low.
t
PXIZ
ALE
PSEN
PORT 0
PORT 2
A0–A15 A8–A15
A0–A7 A0–A7
t
AVLL
t
PXIX
t
LLAX
INSTR IN
t
LHLL
t
PLPH
t
LLIV
t
PLAZ
t
LLPL
t
AVIV
SU00006
t
PLIV
Figure 14. External Program Memory Read Cycle
ALE
PSEN
PORT 0
PORT 2
RD
A0–A7
FROM RI OR DPL
DATA IN A0–A7 FROM PCL INSTR IN
P2.0–P2.7 OR A8–A15 FROM DPF A0–A15 FROM PCH
t
WHLH
t
LLDV
t
LLWL
t
RLRH
t
LLAX
t
RLAZ
t
AVLL
t
RHDX
t
RHDZ
t
AVWL
t
AVDV
t
RLDV
SU00025
Figure 15. External Data Memory Read Cycle
