Samsung S3C8275X - Manual (Page 250)

S3C8275X/F8275X/C8278X/F8278X/C8274X/F8274X I/O PORTS
9-15
PORT 4
Port 4 is an 8-bit I/O port with individually configurable pins. Port 4 pins are accessed directly by writing or reading
the port 4 data register, P4 at location F4H in set 1, bank 0. P4.0-P4.7 can serve as inputs (with or without pull-
up), as push-pull output or you can be configured the following functions.
• Low-nibble pins (P4.0-P4.3): SEG15-SEG12
• High-nibble pins (P4.4-P4.7): SEG11-SEG8
Port 4 Control Registers (P4CONH, P4CONL)
Port 4 has two 8-bit control registers: P4CONH for P4.4-P4.7 and P4CONL for P4.0-P4.3. A reset clears the
P4CONH and P4CONL registers to "00H", configuring all pins to input mode. You use control registers setting to
select input (with or without pull-up) or push-pull output mode and enable the alternative functions.
When programming this port, please remember that any alternative peripheral I/O function you configure using the
port 4 control registers must also be enabled in the associated peripheral module.
Port 4 Control Register, High Byte (P4CONH)
E9H, Set 1, Bank 1, R/W
.7 .6 .5 .4 .3 .2 .1 .0 MSB LSB
P4.5/SEG10 P4.4/SEG11
P4CONH bit-pair pin configuration settings:
00
01
10
11
Push-pull output mode
Alternative function (SEG8-SEG11)
Input with pull-up resistor
Input mode
P4.7/SEG8 P4.6/SEG9
Figure 9-19. Port 4 High-Byte Control Register (P4CONH)