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I/O PORTS
PORT 3
Port 3 is an 5-bit I/O port with individually configurable pins. Port 3 pins are accessed directly by writing or
reading the port 3 data register, P3 at location F9H in set 1, bank 0. P3.0–P3.3 can serve as inputs (with or
without pull-ups), as push-pull outputs, or you can configure the following alternative functions:
— TACAP, TACLK, TAOUT, TAPWM and TBPWM
Port 3 Control Registers
Port 3 has two 8-bit control registers: P3CONH for P3.4 and P3CONL for P3.0–P3.3. A reset clears the P3CONH
and P3CONL registers to "00H", configuring all pins to input mode. You use control registers settings to select
input or output mode, enable pull-up resistors, and enable the alternative functions.
When programming this port, please remember that any alternative peripheral I/O function you configure using
the port 3 control registers must also be enabled in the associated peripheral module.
9-10
Port 3 Control high Register (P3CONH)
E8H, Set 1, Bank 0, R/W
MSB
.7
.6
.5
Not used
P3CONH bit-pair pin configuration settings
00
Input mode
01
Input mode, pull-up
1x
Output mode, push-pull
Figure 9-10. Port 3 Control High Register (P3CONH)
S3C8248/C8245/P8245/C8247/C8249/P8249
.4
.3
.2
.1
P3.4
.0
LSB
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