CHAPTER 7 8-BIT TIMER/EVENT COUNTERS 50 AND 51
Preliminary User’s Manual U19014EJ1V0UD
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(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 pins for timer output, clear PM17 and PM33 and the output
latches of P17 and P33 to 0.
When using the P17/TO50/TI50 and P33/TO51/TI51 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 signal generation sets these registers to FFH.
Figure 7-9. Format of Port Mode Register 1 (PM1)
Address: FF21H After reset: FFH R/W
Symbol
7 6 5 4 3 2 1 0
PM1
PM17 PM16 PM15 PM14 PM13 PM12 PM11 PM10
PM1n
P1n pin I/O mode selection (n = 0 to 7)
0
Output mode (output buffer on)
1
Input mode (output buffer off)
Figure 7-10. Format of Port Mode Register 3 (PM3)
Address: FF23H After reset: FFH R/W
Symbol
7 6 5 4 3 2 1 0
PM3 1 1 1 1
PM33
PM32
PM31
PM30
PM3n
P3n pin I/O mode selection (n = 0 to 3)
0
Output mode (output buffer on)
1
Input mode (output buffer off)
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