NEC 78K0 User Manual page 303

(3) Port mode register 1 (PM1)
PM1 is used to set port 1 input/output in 1-bit units.
When using P10/SCK10 as the clock output pin of the serial interface, and P12/SO10 as the data output pin,
clear PM10, PM12, and the output latches of P10 and P12 to 0.
When using P10/SCK10 as the clock input pin of the serial interface, and P11/SI10/RxD0 as the data input pin,
set PM10 and PM11 to 1. At this time, the output latches of P10 and P11 may be 0 or 1.
PM1 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets this register to FFH.
CHAPTER 14 SERIAL INTERFACE CSI10
Figure 14-4. Format of Port Mode Register 1 (PM1)
Address: FF21H After reset: FFH
Symbol 7 6 5
PM1 PM17 PM16 PM15
PM1n P1n pin I/O mode selection (n = 0 to 7)
0 Output mode (output buffer on)
1 Input mode (output buffer off)
User's Manual U16227EJ2V0UD
R/W
4 3 2 1
PM14 PM13 PM12 PM11 PM10
0
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