Input/Output Ports
Holtek microcontrollers offer considerable flexibility on their I/O ports. With the input or output
designation of every pin fully under user program control, pull-high selections for all ports and
wake-up selections on certain pins, the user is provided with an I/O structure to meet the needs of a
wide range of application possibilities.
The device provides bidirectional input/output lines labeled with port names PA~PF. These I/O ports
are mapped to the RAM Data Memory with specific addresses as shown in the Special Purpose Data
Memory table. All of these I/O ports can be used for input and output operations. For input operation,
these ports are non-latching, which means the inputs must be ready at the T2 rising edge of instruction
²
MOV A,[m]
²
, where m denotes the port address. For output operation, all the data is latched and
remains unchanged until the output latch is rewritten.
I/O Register List
BS83B08-3
Register
Name
Bit
7
6
5
4
3
2
1
0
PAWU
¾
¾
¾
D4
D3
D2
D1
D0
PAPU
¾
¾
¾
D4
D3
D2
D1
D0
PA
¾
¾
¾
D4
D3
D2
D1
D0
PAC
¾
¾
¾
D4
D3
D2
D1
D0
PBPU
D7
D6
D5
D4
D3
D2
D1
D0
PB
D7
D6
D5
D4
D3
D2
D1
D0
PBC
D7
D6
D5
D4
D3
D2
D1
D0
BS83B12-3
Register
Name
Bit
7
6
5
4
3
2
1
0
PAWU
¾
¾
¾
D4
D3
D2
D1
D0
PAPU
¾
¾
¾
D4
D3
D2
D1
D0
PA
¾
¾
¾
D4
D3
D2
D1
D0
PAC
¾
¾
¾
D4
D3
D2
D1
D0
PBPU
D7
D6
D5
D4
D3
D2
D1
D0
PB
D7
D6
D5
D4
D3
D2
D1
D0
PBC
D7
D6
D5
D4
D3
D2
D1
D0
PCPU
¾
¾
¾
¾
D3
D2
D1
D0
PC
¾
¾
¾
¾
D3
D2
D1
D0
PCC
¾
¾
¾
¾
D3
D2
D1
D0
Rev. 1.50
60
April 28, 2020
BS83B08-3/B12-3/B16-3/B16G-3/C24-3
8-Bit Touch Key Flash MCU