W78E58B Winbond, W78E58B Datasheet - Page 10

• Manufacturer Part Number: W78E58B
• Description: 8 BIT MICROCONTROLLER
• Manufacturer: Winbond

Port 4 Base Address Registers
P40AH, P40AL
The Base address register for comparator of P4.0. P40AH contains the high-order byte of address,
P40AL contains the low-order byte of address.
P41AH, P41AL
The Base address register for comparator of P4.1. P41AH contains the high-order byte of address,
P41AL contains the low-order byte of address.
P42AH, P42AL
The Base address register for comparator of P4.2. P42AH contains the high-order byte of address,
P42AL contains the low-order byte of address.
P43AH, P43AL
The Base address register for comparator of P4.3. P43AH contains the high-order byte of address,
P43AL contains the low-order byte of address.
P4 (D8H)
Here is an example to program the P4.0 as a write strobe signal at the I/O port address 1234H 1237H
and positive polarity, and P4.1
MOV P40AH, #12H
MOV P40AL, #34H
MOV P4CONA, #00001010B
MOV P4CONB, #00H
MOV P2ECON, #10H
Then any instruction MOVX @DPTR, A (with DPTR = 1234H
polarity write strobe signal at pin P4.0. And the instruction MOV P4, #XX will output the bit3 to bit1 of
data #XX to pin P4.3
BIT
7
6
5
4
3
2
1
0
NAME
P43
P42
P41
P40
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-
-
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P4.1.
P4.3 are used as general I/O ports.
; Base I/O address 1234H for P4.0
; P4.0 a write strobe signal and address line A0 and A1 are masked.
; P4.1
; Write the P40SINV = 1 to inverse the P4.0 write strobe polarity
; default is negative.
Reserve
Reserve
Reserve
Reserve
Port 4 Data bit which outputs to pin P4.3 at mode 0.
Port 4 Data bit. which outputs to pin P4.2 at mode 0.
Port 4 Data bit. which outputs to pin P4.1at mode 0.
Port 4 Data bit which outputs to pin P4.0 at mode 0.
P4.3 as general I/O port which are the same as PORT1
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FUNCTION
1237H) will generate the positive
W78E58B