Registers For Port 3 (Pdr3, Ddr3) - Fujitsu MB90895 Series Hardware Manual

4.5.1

Registers for Port 3 (PDR3, DDR3)

The registers for port 3 are explained.
I Function of Registers for Port 3
G
Port 3 data register (PDR3)
• Port 3 data register indicates the state of the pins.
G
Port 3 direction register (DDR3)
• The port 3 direction register sets the input/output directions.
• When the bit corresponding to the pin is set to "1", port 1 functions as an output port. When the bit is set
to "0", port 1 functions as an input port.
Table 4.5-3 shows function of the registers for port 3.
Table 4.5-3 Functions of the Registers for Port 3
Register
Data
Name
0
Port 3 data
register
(PDR3)
1
0
Port 3
direction
register
(DDR3)
1
R/W: Read/Write
X: Undefined
Reference: • When using port 3 as the input pin of the resource, clear the bit in the DDR3
corresponding to the input pin of the resource to 0 and set the input pin as an input port.
• When using the port as the output of the resource, set the output of the corresponding
resource to enabled. Port 3 functions as the output pin of the resource regardless of the
settings of the DDR3.
At Read
"0" is set for the output
The pin state is latch, and when the pin is an
Low level. output port pin, the Low
level is output to the pin.
"1" is set for the output
The pin state is latch, and when the pin is an
High level. output port pin, the High
level is output to the pin.
The output buffer is set to
The direction
"OFF", and the pin becomes
latch is "0".
an input port pin.
The output buffer is set to
The direction
"ON", and the pin becomes
latch is "1".
an output port pin
Read/
At Write
Write
R/W
R/W
CHAPTER 4 I/O PORT
Register
Reset Value
Address
000003 XXXXXXXX
H B
000013 000X0000
H B
175