
148
CHAPTER 4 I/O PORTS
4.5.1
Port-4, Port-6, and Port-7 Registers (PDR4, PDR6, and
PDR7)
This section describes the port-4, port-6, and port-7 registers.
s Port-4, port-6, and port-7 Register Functions
r Port 4, port 6, and port 7 data registers (PDR4, PDR6, and PDR7)
The PDR4, 6, and 7 registers hold the states of their respective output data latches. Therefore,
you cannot determine the pin states or LCDC common and segment output states by reading
the registers.
r Settings as an LCDC common and segment output
To use pins as LCDC common and segment outputs, that function must be selected by a mask
option (MB89983) or by control register (MB89P985 and MB89PV980). The register bits for pins
used for this purpose should be set to turn the output transistor "OFF" to prevent it from
interfering with the LCDC common and segment output.
Table 4.5-3 "Port-4, Port-6, and Port-7 Register Function" lists the functions of Port-4, port-6,
and port-7 register.
Table 4.5-3 Port-4, Port-6, and Port-7 Register Function
Register
Data
Read
Write
Read/
Write
Address
Initial value
Port 4 data
register
(PDR4)
0
Output latch
value is "0".
Sets "0" to the output latch.
Outputs an "L" level to the
pin.
R/W
000EH
11111111B
1
Output latch
value is "1".
Sets "1" to the output latch.
Outputs an "H" level to the
pin.
Port 4 data
register
(PDR4)
0
Output latch
value is "0".
Sets "0" to the output latch.
Outputs an "L" level to the
pin.
R/W
0012H
XX111111B
1
Output latch
value is "1".
Sets "1" to the output latch.
Outputs an "H" level to the
pin.
Port 4 data
register
(PDR4)
0
Output latch
value is "0".
Sets "0" to the output latch.
Outputs an "L" level to the
pin.
R/W
0013H
XXXXXX11B
1
Output latch
value is "1".
Sets "1" to the output latch.
Outputs an "H" level to the
pin.