OM5202 Datasheet, PDF (9/11 Pages) NXP Semiconductors – ROMless 8-bit microcontroller

Philips Semiconductors
ROMless 8-bit microcontroller
Product specification
OM5202
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.
ALE
PSEN
PORT 0
PORT 2
t_LHLL
t_AVLL
t_LLAX
A0–A7
t_PLPH
t_LLPL
t_LLIV
t_PLIV
t_PLAZ
t_PXIX
t_PXIZ
INSTR IN
t_AVIV
A8–A15
A0–A7
A8–A15
Figure 2. External Program Memory Read Cycle
ALE
PSEN
RD
PORT 0
PORT 2
t_LLDV
t_LLWL
t_RLRH
t_WHLH
t_AVLL
t_LLAX
A0–A7
FROM RI OR DPL
t_RLDV
t_RLAZ
t_RHDX
DATA IN
t_AVWL
t_AVDV
P2.0–P2.7 OR A8–A15 FROM DPH
t_RHDZ
A0–A7 FROM PCL
A8–A15 FROM PCH
Figure 3. External Data Memory Read Cycle
December 1994
9
INSTR IN