User’s Manual
C166S V1 SubSystem
Parallel Ports
User’s Manual
7-4
V 1.6, 2001-08
Alternate Functions of PORT0
When an external bus is enabled, PORT0 is used as data bus or address/data bus.
Note that an external 8-bit demultiplexed bus only uses P0L, while P0H is free for IO
(provided that no other bus mode is enabled).
During external accesses in multiplexed bus modes PORT0 first outputs the 16-bit intra-
segment address as an alternate output function. PORT0 is then switched to high-
impedance input mode to read the incoming instruction or data. In 8-bit data bus mode,
two memory cycles are required for word accesses, the first for the low byte and the
second for the high byte of the word. During write cycles PORT0 outputs the data byte
or word after outputting the address.
P0H
PORT0 High Register
SFR (FF02
H
/81
H
)
Reset value: - - 00
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
P0H
.7
P0H
.6
P0H
.5
P0H
.4
P0H
.3
P0H
.2
P0H
.1
P0H
.0
-
-
-
-
-
-
-
-
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
P0X.y
Port data register P0H or P0L bit y
DP0L
P0L Direction Ctrl. Register
ESFR (F100
H
/80
H
)
Reset value: - - 00
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
DP0L
.7
DP0L
.6
DP0L
.5
DP0L
.4
DP0L
.3
DP0L
.2
DP0L
.1
DP0L
.0
-
-
-
-
-
-
-
-
rw
rw
rw
rw
rw
rw
rw
rw
DP0H
P0H Direction Ctrl. Register
ESFR (F102
H
/81
H
)
Reset Value: - - 00
H
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
DP0H
.7
DP0H
.6
DP0H
.5
DP0H
.4
DP0H
.3
DP0H
.2
DP0H
.1
DP0H
.0
-
-
-
-
-
-
-
-
rw
rw
rw
rw
rw
rw
rw
rw
Bit
Function
DP0X.y
Port direction register DP0H or DP0L bit y
DP0X.y = 0: Port line P0X.y is an input (high-impedance)
DP0X.y = 1: Port line P0X.y is an output
Содержание C166S V1 SubSystem
Страница 10: ...User s Manual C166S V1 SubSystem User s Manual I 6 V 1 6 2001 08...
Страница 16: ...User s Manual C166S V1 SubSystem Introduction User s Manual 1 6 V 1 6 2001 08...
Страница 126: ...User s Manual C166S V1 SubSystem Central Processing Unit User s Manual 3 96 V 1 6 2001 08...
Страница 178: ...User s Manual C166S V1 SubSystem Memory Organization User s Manual 4 52 V 1 6 2001 08...
Страница 206: ...User s Manual C166S V1 SubSystem Instruction Set User s Manual 5 28 V 1 6 2001 08...
Страница 306: ...User s Manual C166S V1 SubSystem Detailed Instruction Set User s Manual 6 100 V 1 6 2001 08...
Страница 362: ...User s Manual C166S V1 SubSystem The External Bus Interface User s Manual 8 40 V 1 6 2001 08...
Страница 452: ...User s Manual C166S V1 SubSystem General Purpose Timer Unit User s Manual 12 44 V 1 6 2001 08...
Страница 454: ...User s Manual C166S V1 SubSystem Instruction Index User s Manual 13 2 V 1 6 2001 08...
Страница 459: ......