BS83A04A-3 Datasheet, PDF (38/72 Pages) Holtek Semiconductor Inc – Touch Key 8-bit Flash MCU

BS83A04A-3/BS83A04A-4
8-bit Touch Key Flash MCU
Port A Wake-up
The HALT instruction forces the microcontroller into the SLEEP or IDLE Mode which preserves
power, a feature that is important for battery and other low-power applications. Various methods
exist to wake-up the microcontroller, one of which is to change the logic condition on one of the Port
A pins from high to low. This function is especially suitable for applications that can be woken up
via external switches. Each pin on Port A can be selected individually to have this wake-up feature
using the PAWU register.
PAWU Register
Bit
7
6
5
4
3
2
1
0
Name
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
Bit 7~0
PAWU: PA wake-up function control
0: disable
1: enable
I/O Port Control Registers
The I/O port has its own control register known as PAC, to control the input/output configuration.
With this control register, each CMOS output or input can be reconfigured dynamically under
software control. Each pin of the I/O port is directly mapped to a bit in its associated port control
register. For the I/O pin to function as an input, the corresponding bit of the control register must
be written as a "1". This will then allow the logic state of the input pin to be directly read by
instructions. When the corresponding bit of the control register is written as a "0", the I/O pin will
be setup as a CMOS output. If the pin is currently setup as an output, instructions can still be used
to read the output register. However, it should be noted that the program will in fact only read the
status of the output data latch and not the actual logic status of the output pin.
PAC Register
Bit
7
6
5
4
3
2
1
0
Name
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
1
1
1
1
1
1
1
1
Bit 7~0
PAC: I/O Port bit 7 ~ bit 0 Input/Output Control
0: output
1: input
Rev. 1.00
38
February 28, 2013