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(2) Port A Data Register (PADR)
7
—
Undefined
—
6
—
Undefined
—
5
—
Undefined
—
4
—
Undefined
—
3
PA3DR
0
R/W
0
PA0DR
0
R/W
2
PA2DR
0
R/W
1
PA1DR
0
R/W
Bit
:
Initial value :
R/W
:
PADR is an 8-bit readable/writable register that stores output data for the port A pins (PA3 to
PA0).
Bits 7 to 4 are reserved; these bits cannot be modified and will return an undefined value if read.
PADR is initialized to H'0 (bits 3 to 0) by a power-on reset and in hardware standby mode. It
retains its previous state after a manual reset and in software standby mode.
(3) Port A Register (PORTA)
7
—
Undefined
—
6
—
Undefined
—
5
—
Undefined
—
4
—
Undefined
—
3
PA3
—*
R
0
PA0
—*
R
2
PA2
—*
R
1
PA1
—*
R
Bit
:
Initial value :
R/W
:
Note: * Determined by the state of pins PA3 to PA0.
PORTA is an 8-bit read-only register that shows the pin states. It cannot be written to. Writing of
output data for the port A pins (PA3 to PA0) must always be performed on PADR.
Bits 7 to 4 are reserved; these bits cannot be modified and will return an undefined value if read.
If a port A read is performed while PADDR bits are set to 1, the PADR values are read. If a port
A read is performed while PADDR bits are cleared to 0, the pin states are read.
After a power-on reset and in hardware standby mode, PORTA contents are determined by the pin
states, as PADDR and PADR are initialized. PORTA retains its previous state after a manual reset
and in software standby mode.