BS85B12-3_12 Datasheet, PDF (60/183 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3/BS85C20-5
Touch Key Flash MCU with LCD/LED Driver
Pull-high Resistors
Many product applications require pull-high resistors for their switch inputs usually requiring the
use of an external resistor. To eliminate the need for these external resistors, all I/O pins, when
configured as an input have the capability of being connected to an internal pull-high resistor. These
pull-high resistors are selected using the register PAPU~PEPU, and are implemented using weak
PMOS transistors.
BS85B12-3: PAPU, PCPU Registers
BS85C20-3/BS85C20-5: PAPU, PBPU, PCPU, PDPU Registers
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
PxPU: Port bit 7~bit 0 Pull-High control
0: disable
1: enable
BS85B12-3: PBPU Registers
BS85C20-3/BS85C20-5: PEPU Registers
Bit
7
6
5
4
3
2
1
0
Name
—
—
D5
D4
D3
D2
D1
D0
R/W
—
—
R/W
R/W
R/W
R/W
R/W
R/W
POR
—
—
0
0
0
0
0
0
Bit 7~4
Bit 3~0
unimplemented, read as "0"
PxPU: Port bit 5~bit 0 Pull-High control
0: disable
1: enable
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 7~5
Bit 4~0
unimplemented, read as "0"
PAWU: Port A bit 7~bit 0 wake-up control
0: disable
1: enable
Rev. 1.20
60
August 10, 2012