CHAPTER 4 PORT FUNCTIONS
User’s Manual U15331EJ4V1UD
91
4.3 Registers Controlling Port Function
The ports are controlled by the following three types of registers.
•
Port mode registers (PM0 to PM3, PM5, PM8)
•
Pull-up resistor option registers (PUB0 to PUB3)
•
Port function registers (PF7, PF8) (
µ
PD78F9488, 78F9489 only)
(1) Port mode registers (PM0 to PM3, PM5, PM8)
Input and output can be specified in 1-bit units.
These registers can be set with a 1-bit or 8-bit memory manipulation instruction.
RESET input sets these registers to FFH.
When using the port pins as their alternate functions, set the port mode register and the output latch as
shown in Table 4-3.
Caution Because P30 to P33 function alternately as external interrupt inputs, when the output level
changes after the output mode of the port function is specified, the interrupt request flag
will be inadvertently set. Therefore, be sure to preset the interrupt mask flag (PMK0 to
PMK3) before using the port in output mode.
Figure 4-15. Port Mode Register Format
Symbol
7 6 5 4 3 2 1 0
Address
After
reset
R/W
PM0 PM07 PM06 PM05 PM04 PM03 PM02 PM01 PM00 FF20H
FFH R/W
PM1
1 1 1 1 1 1
PM11
PM10
FF21H
FFH
R/W
PM2 1
1 PM25 PM24 PM23 PM22 PM21 PM20 FF22H
FFH R/W
PM3 1
1
1 PM34 PM33 PM32 PM31 PM30 FF23H
FFH R/W
PM5
1 1 1 1
PM53
PM52
PM51
PM50
FF25H
FFH
R/W
PM8 PM87 PM86 PM85 PM84 PM83 PM82 PM81 PM80 FF28H
FFH R/W
PMmn
Pmn pin input/output mode selection
(m = 0 to 3, 5, 8, n = 0 to 7)
0
Output mode (output buffer on)
1
Input mode (output buffer off)
Remark
PM8 can only be used when one of pins P80 to P87 is selected as a port function pin by a mask
option or port function register 8 (PF8).
Содержание PD789488
Страница 2: ...2 User s Manual U15331EJ4V1UD MEMO ...