NEC 78K0 User Manual page 168

(3) Port mode registers 1 and 3 (PM1, PM3)
These registers set port 1 and 3 input/output in 1-bit units.
When using the P17/TO50/TI50 and P33/TO51/TI51/INTP4 pins for timer output, set PM17 and PM33 and the
output latches of P17 and P33 to 0.
When using the P17/TO50/TI50 and P33/TO51/TI51/INTP4 pins for timer input, set PM17 and PM33 to 1. The
output latches of P17 and P33 at this time may be 0 or 1.
PM1 and PM3 can be set by a 1-bit or 8-bit memory manipulation instruction.
RESET input sets these registers to FFH.
Address: FF21H After reset: FFH
Symbol 7
PM1 PM17
PM1n
0 Output mode (output buffer on)
1 Input mode (output buffer off)
Address: FF23H After reset: FFH
Symbol 7
PM3 0
PM3n
0 Output mode (output buffer on)
1 Input mode (output buffer off)
168
CHAPTER 7 8-BIT TIMER/EVENT COUNTERS 50 AND 51
Figure 7-9. Format of Port Mode Register 1 (PM1)
R/W
6 5 4
PM16 PM15 PM14
P1n pin I/O mode selection (n = 0 to 7)
Figure 7-10. Format of Port Mode Register 3 (PM3)
R/W
6 5 4
0 0 0
P3n pin I/O mode selection (n = 0 to 3)
User's Manual U16227EJ2V0UD
3 2 1
PM13 PM12 PM11
3 2 1
PM33 PM32 PM31
0
PM10
0
PM30