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S3F80N8_UM_REV1.10
PORT 0
Port 0 is an 8-bit I/O port with individually configurable pins. Port 0 pins are accessed directly by writing or reading the port 0 data register, P0 at location E0H. P0.0-0.7 can serve as inputs and as outputs (push-pull or opendrain).
Port 0 Control Registers (P0CONH, P0CONL)
Port 0 has two 8-bit control registers: P0CONH for P0.4-0.7 and P0CONL for P0.0-0.3. A reset clears the
P0CONH and P0CONL registers to "00H". You use control registers setting to select input or output mode (pushpull or open-drain).
Port 0 Pull-Up Resistor Control Register (P0PUR)
Using the port0 pull-up resistor control register, P0PUR (E6H), you can configure pull-up resistors to individual port.
MSB .7
Port 0 Control Register, High-byte (P0CONH)
E4H, R/W
.6
.5
.4
.3
.2
.1
.0
LSB
P0.4
P0.5
P0.6
P0.7
P0CONH bit-pair pin configuration
0 0
0 1
1 0
1 1
Normal input mode
Output mode, push-pull
Output mode, open-drain
Not used
Figure 9-1. Port 0 High-Byte Control Register (P0CONH)
9-3
I/O PORTS
MSB .7
Port 0 Control Register, Low-byte (P0CONL)
E5H, R/W
.6
.5
.4
.3
.2
.1
.0
LSB
P0.0
P0.1
P0.2
P0.3
P0CONL bit-pair pin configuration
0 0
0 1
1 0
1 1
Normal input mode
Output mode, push-pull
Output mode, opne-drain
Not used
Figure 9-2. Port 0 Low-Byte Control Register (P0CONL)
MSB .7
Port 0 Pull-up Control Register (P0PUR)
E6H, R/W
.6
.5
.4
.3
.2
.1
.0
LSB
P0.7
P0.6
P0.5
P0.4
P0.3
P0.2
P0.1
P0.0
P0PUR bit configuration settings:
0
1
Disable pull-up resistor
Enable pull-up resistor
Figure 9-3. Port 0 Pull-up Control Register (P0PUR)
S3F80N8_UM_REV1.10
9-4
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