5.2 Port 1
Port 1 is an 8-bit input/output port that also provides the low bits of the address bus. The function
of port 1 depends on the MCU mode as indicated in table 5-2.
Table 5-2. Functions of Port 1
Note: * Depending on the bit settings in the data direction register: 0—input pin; 1—address pin
Pins of port 1 can drive a single TTL load and a 90pF capacitive load when they are used as output
pins. They can also drive light-emitting diodes and a Darlington pair. When they are used as input
pins, they have programmable MOS transistor pull-ups.
Table 5-3 details the port 1 registers.
Table 5-3. Port 1 Registers
Port 1 Data Direction Register (P1DDR)—H'FFB0
Mode 1
Mode 2
Mode 3
Address bus (Low)
Input port or
Input/output port
(A
7
to A
0
)
Address bus (Low)
(A
7
to A
0
)*
Name
Abbreviation Read/Write
Initial value
Address
Port 1 data direction register P1DDR
W
H'FF (mode 1)
H'FFB0
H'00 (modes 2 and 3)
Port 1 data register
P1DR
R/W
H'00
H'FFB2
Port 1 input pull-up control
P1PCR
R/W
H'00
H'FFAC
register
Bit
7
6
5
4
3
2
1
0
P1
7
DDR P1
6
DDR P1
5
DDR P1
4
DDR P1
3
DDR P1
2
DDR P1
1
DDR P1
0
DDR
Mode 1
Initial value
1
1
1
1
1
1
1
1
Read/Write
—
—
—
—
—
—
—
—
Modes 2 and 3
Initial value
0
0
0
0
0
0
0
0
Read/Write
W
W
W
W
W
W
W
W
77
Summary of Contents for H8/326 Series
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