CHAPTER 14 PORT FUNCTIONS
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User’s Manual U14492EJ3V0UD
14.3.4 Port 3
Port 3 is an 8-bit I/O port in which input or output can be specified in 1-bit units.
7
P37
P3
6
P36
5
P35
4
P34
3
P33
2
P32
1
P31
0
P30
Address
FFFFF406H
Initial value
Undefined
Bit Position
Bit Name
Function
7 to 0
P3n
(n = 7 to 0)
I/O port
Besides functioning as a port, in control mode, it also can operate as the serial interface (UART0 to UART2) I/O.
(1) Operation in control mode
Port
Alternate Pin Name
Remarks
Block Type
P30
RXD0
H
P31
TXD0
G
P32
RXD1
C
P33
TXD1
A
P34
ASCK1
M
P35
RXD2
C
P36
TXD2
A
Port 3
P37
ASCK2
Serial interface (UART0 to UART2) I/O
M
(2) Setting in I/O mode and control mode
Port 3 is set in I/O mode using the port 3 mode register (PM3). In control mode, it is set using the port 3
mode control register (PMC3).
(a) Port 3 mode register (PM3)
This register can be read/written in 8-bit or 1-bit units.
7
PM37
PM3
6
PM36
5
PM35
4
PM34
3
PM33
2
PM32
1
PM31
0
PM30
Address
FFFFF426H
Initial value
FFH
Bit Position
Bit Name
Function
7 to 0
PM3n
(n = 7 to 0)
Specifies input/output mode of P3n pin.
0: Output mode (output buffer on)
1: Input mode (output buffer off)