UPD784938 Datasheet, PDF (57/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 2 PIN FUNCTIONS
(iii) CI (Clock Input)
The timer/event counter 2 external clock input pin.
(iv) ASCK (Asynchronous Serial Clock)
The external baud rate clock input pin.
(v) SCK1 (Serial Clock)
The serial clock input/output pin (in 3-wire serial I/O1 mode).
(vi) SI0 (Serial Input 0)
The serial data input pin (in 3-wire serial I/O0 mode).
(4) P30 to P37 (Port 3) ... 3-state input/output
Port 3 is an 8-bit input/output port with an output latch. Input/output can be specified bit-wise 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 control signal pin alternate functions.
The operation mode can be specified in 1-bit units by setting the port 3 mode control register (PMC3), as shown in
Table 2-3. The pin level of any pin can always be read or tested regardless of the alternate-function 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 2-3. Port 3 Operation Modes (n = 0 to 7)
Mode
Setting Condition
P30
P31
P32
P33
P34
P35
P36
P37
Port Mode
PMC3n = 0
Input/output port
Control Signal Input/Output Mode
PMC3n = 1
RxD input / SI1 input
TxD output / SO1 output
SCK0 input/output
SO0 output
TO0 output
TO1 output
TO2 output
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 in 1-
bit units 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/O1 mode).
Preliminary User’s Manual U13987EJ1V0UM00
57