W78E365/W78E365A
W78E365 Special Function Registers (SFRs) and Reset Values, continued
+IP
B8
CHPCON
00000000
0xx00000
+P3
00000000
+IE
P43AL
P43AH
B0
A8
A0
98
90
88
00000000
P42AL
00000000
P42AH
P4CSIN
00000000
+P2
00000000
00000000
00000000
XRAMAH
00000000
SBUF
11111111
+SCON
00000000
+P1
xxxxxxxx
P41AL
00000000
TH0
P41AH
00000000
TH1
11111111
+TCON
00000000
+P0
TMOD
00000000
SP
TL0
TL1
AUXR
00000000
POR
WDTC
00000000
PCON
00000000
DPL
00000000
DPH
00000000
P40AL
00000000
P40AH
80
11111111
00000111
00000000
00000000
00000000
00000000
00000000
00110000
Notes:
1. The SFRs marked with a plus sign(+) are both byte- and bit-addressable.
2. The text of SFR with bold type characters are extension function registers.
6.6 Port 4
Port 4, address D8H, is a 8-bit multipurpose programmable I/O port. Each bit can be configured
individually by software. The Port 4 has four different operation modes.
Mode 0: P4.0−P4.3 is a bi-directional I/O port which is same as port 1. P4.2 and P4.3 also serve as
PSEN
external interrupt
and INT2 if enabled.
Mode 1: P4.0−P4.3 are read strobe signals that are synchronized with RD signal at specified
addresses. These signals can be used as chip-select signals for external peripherals.
Mode 2: P4.0−P4.3 are write strobe signals that are synchronized with WRsignal at specified
addresses. These signals can be used as chip-select signals for external peripherals.
Mode 3: P4.0−P4.3 are read/write strobe signals that are synchronized with RD or WRsignal at
specified addresses. These signals can be used as chip-select signals for external
peripherals.
When Port 4 is configured with the feature of chip-select signals, the chip-select signal address range
depends on the contents of the SFR P4xAH, P4xAL, P4CONA and P4CONB. The registers P4xAH
and P4xAL contain the 16-bit base address of P4.x. The registers P4CONA and P4CONB contain the
control bits to configure the Port 4 operation mode.
- 10 -
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