UPD784938 Datasheet, PDF (138/733 Pages) NEC – 16-Bit Single-Chip Microcontrollers

CHAPTER 6 PORT 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 1)
The serial clock input/output pin (in 3-wire serial I/O 1 mode)
(vi) SI0 (Serial Input 0)
The serial data input pin (in 3-wire serial I/O 0 mode)
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Preliminary User’s Manual U13987EJ1V0UM00