Philips Semiconductors
Preliminary specification
80C51 8-bit microcontroller
8K/256 OTP, 8 channel 10 bit A/D, I2C, PWM,
capture/compare, high I/O, low voltage (2.7V–5.5V), low power
P87C552
ALE
t
WHLH
PSEN
t
t
WLWH
LLWL
WR
t
t
t
LLAX
WHQX
t
AVLL
QVWX
t
DW
A0–A7
FROM RI OR DPL
PORT 0
PORT 2
DATA OUT
A0–A7 FROM PCL
INSTR IN
t
AVWL
P2.0–P2.7 OR A8–A15 FROM DPH
A8–A15 FROM PCH
SU00213
Figure 50. External Data Memory Write Cycle
V
–0.5
CC
0.7V
CC
–0.1
0.45V
0.2V
CC
t
CHCX
t
t
t
CHCL
CLCX
CLCH
t
CLCL
SU00009
Figure 51. External Clock Drive XTAL1
INSTRUCTION
ALE
0
1
2
3
4
5
6
7
8
t
XLXL
CLOCK
t
XHQX
t
QVXH
OUTPUT DATA
0
1
2
3
4
5
6
7
WRITE TO SBUF
t
XHDX
t
SET TI
VALID
XHDV
INPUT DATA
CLEAR RI
VALID
VALID
VALID
VALID
VALID
VALID
VALID
SET RI
SU00027
Figure 52. Shift Register Mode Timing
68
1999 Mar 30