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S3C9228/P9228 I/O PORTS
9-9
PORT 2
Port 2 is an 4-bit I/O port with individually configurable pins. Port 2 pins are accessed directly by writing or
reading the port 2 data register, P2 at location E6H in page 0. P2.0-P2.3 can serve as inputs (with or without pull-
up), as outputs (push-pull or open-drain) or you can be configured the following functions.
— Low-nibble pins (P2.0-P2.3): SCK, SO, SI, SEG0-SEG1
Port 2 Control Register (P2CON)
Port 2 has a 8-bit control register: P2CON for P2.0-P2.3. A reset clears the P2CON register to "00H", configuring
pins to input mode. You use control register setting to select input or output mode (push-pull or open-drain) and
enable the alternative functions.
When programming this port, please remember that any alternative peripheral I/O function you configure using
the port 2 control register must also be enabled in the associated peripheral module.
Port 2 Pull-up Resistor Control Register (P2PUR)
Using the port 2 pull-up resistor control register, P2PUR (F4H, page 0), you can configure pull-up resistors to
individual port 2 pins.
Port 2 Control Register (P2CON)
F3H, Page 0, R/W
.7 .6 .5 .4 .3 .2 .1 .0MSB LSB
P2.3
P2CON bit-pair pin configuration settings:
00
01
10
11
N-channel open-drain output mode
Alternative function (SCK, SO)
P2.2/SI P2.1/SO/SEG0 P2.0/SCK/SEG1
Push-pull output mode
Schmitt trigger input mode (SI,SCK)
Figure 9-12. Port 2 Control Register (P2CON)