UPD784938 Datasheet, PDF (143/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT FUNCTIONS
6.5 Port 3
Port 3 is an 8-bit input/output port with an output latch. Input/output can be specified in 1-bit units by setting the port 3 mode
register (PM3). Each pin incorporates a software programmable pull-up resistor. P32 and P33 can be set in the N-ch open-
drain mode.
In addition to its function as an input/output port, port 3 also has various alternate-function control signal pin functions.
The operation mode can be specified in 1-bit units by setting the port 3 mode control register (PMC3), as shown in
Table 6-5. The pin level of all pins can always be read or tested regardless of the alternate-function pin operation.
When RESET is input, port 3 is set as an input port (output high-impedance state), and the output latch contents are undefined.
Table 6-5. Port 3 Operation Modes
(n = 0 to 7)
Mode
Port Mode
Control Signal Input/Output Mode
Setting Condition
PMC3n = 0
PMC3n = 1
P30
Input/output port
RxD input/SI1 input
P31
TxD output/SO1 output
P32
SCK0 input/output
P33
SO0 output
P34
TO0 output
P35
TO1 output
P36
TO2 output
P37
TO3 output
(a) Port mode
Each port specified as port mode by the port 3 mode control register (PMC3) can be specified as input/output bit-wise
by setting the port 3 mode register (PM3).
(b) Control signal input/output mode
Pins can be set as control pins in 1-bit units by setting the port 3 mode control register (PMC3).
(i) RxD (Receive Data) /SI1 (Serial Input 1)
RxD is the asynchronous serial interface serial data input pin. SI1 is the serial data input pin (in 3-wire serial
I/O 1 mode).
(ii) TxD (Transmit Data) /SO1 (Serial Output 1)
TxD is the asynchronous serial interface serial data output pin. SO1 is the serial data output pin (in 3-wire serial
I/O 1 mode).
(iii) SCK0 (Serial Clock 0)
SCK0 is the clocked serial interface serial clock input/output pin (in 3-wire serial I/O 0 mode).
(iv) SO0 (Serial Output 0)
SO0 is the serial data output pin (in 3-wire serial I/O 0 mode).
(v) TO0 to TO3 (Timer Output)
Timer output pins
Preliminary User’s Manual U13987EJ1V0UM00
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