Table 4.3.1 Port 2 Register Function - Fujitsu F2MC-8L MB89620 Series Hardware Manual

4.3 Port 2
4.3.1 Port 2 Registers (PDR2, BCTR)
This section describes the functions of the port 2 registers.
n Port-2 Register Functions
l Port 2 data register (PDR2)
Writing data to the PDR2 register outputs the data directly to a port. Also, reading the PDR2
register always returns the output latch data.
External bus pin control register (BCTR)
l
The BCTR register controls the functions of P20/BUFC to P22/HRQ in external bus mode. The
hold enable bit (BCTR: HLD) corresponds to P21/HAK and P22/HRQ, and the buffer control
enable bit (BCTR: BUF) corresponds to P20/BUFC.
Check: As the external bus pin control register (BCTR) is write-only, the bit manipulation instructions
Table 4.3.1 lists the functions of the port 2 registers.

Table 4.3.1 Port 2 Register Function

Register
Port 2 data register
(PDR2)
External bus pin
control register
(BCTR)
R/W : Readable and writable
W : Write-only
X : Indeterminate
* : Writing is permitted in external bus mode only. Accessing the external bus pin control register (BCTR) in single-
chip mode has no meaning.
96
CHAPTER 4 I/O PORTS
(SETB and CLRB) cannot be used.
Data
The output latch
0
value is "0".
The output latch
1
value is "1".
0
Reading is not
permitted (write-
only).
1
DRead Write
Outputs an "L" level to
the pin.
(Sets "0" to the output
latch.)
Outputs an "H" level to
the pin.
(Sets "1" to the output
latch.)
Sets the pin as an
output-only port.
Sets the pin as an
external bus control pin.
Read/
Address Initial value
Write
R/W 0004 00000000
H
*
0005 XXXXXX01
W
H
MB89620 series
B
B