HT45R22E Holtek Semiconductor, HT45R22E Datasheet - Page 30

• Manufacturer Part Number: HT45R22E
• Description: Remote Type 8-bit OTP MCU
• Manufacturer: Holtek Semiconductor

Input/Output Ports
Holtek microcontrollers offer considerable flexibility on
their I/O ports. Most pins can have either an input or out-
put designation under user program control. Addi-
tionally, as there are pull-high resistors and wake-up
software configurations, the user is provided with an I/O
structure to meet the needs of a wide range of applica-
tion possibilities.
For input operation, these ports are non-latching, which
means the inputs must be ready at the T2 rising edge of
instruction MOV A,[m] , where m denotes the port ad-
dress. For output operation, all the data is latched and
remains unchanged until the output latch is rewritten.
Pull-high Resistors
Many product applications require pull-high resistors for
their switch inputs usually requiring the use of an exter-
nal resistor. To eliminate the need for these external re-
sistors, when configured as an input have the capability
of being connected to an internal pull-high resistor.
These pull-high resistors are selectable via a register
known as PAPU, PBPU and PCPU located in the Data
Memory. The pull-high resistors are implemented using
weak PMOS transistors. Note that pin PA7 does not
have a pull-high resistor selection.
Rev. 1.00
PAWK, PAC, PAPU, PBC, PBPU, PCWK, PCC, PCPU Registers
Register
PAWK
PCWK
PCPU
Name
PAPU
PBPU
PAC
PBC
PCC
POR
FFH
00H
00H
3FH
00H
00H
FFH
00H
PAWKn, PCWKn: PA, PC wake-up function enable
PACn/PBCn/PCCn: I/O type selection
PAPUn/PBPUn/PCPUn: Pull-high function enable
0: disable
1: enable
0: output
1: input
0: disable
1: enable
Unimplemented, read as 0
PAWK7
PCWK7
PCPU7
PAC7
PCC7
7
PAWK6
PCWK6
PAPU6
PCPU6
PCC6
PAC6
6
PCWK5
PAWK5
PAPU5
PBPU5
PCPU5
PAC5
PBC5
PCC5
5
30
PAWK4
PCWK4
PCPU4
Port A, Port C Wake-up
If the HALT instruction is executed, the device will enter
the Idle/Sleep Mode, where the system clock will stop
resulting in power being conserved, a feature that is im-
portant 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 PA0~PA7 or PC0~PC7 pins from high to low. After a
HALT instruction forces the microcontroller into entering
the Idle/Sleep Mode, the processor will remain idle or in
a low-power state until the logic condition of the selected
wake-up pin on Port A or Port C changes from high to
low. This function is especially suitable for applications
that can be woken up via external switches. Note that
pins PA0 to PA7 and PC0~PC7 can be selected individ-
ually to have this wake-up feature using an internal reg-
ister known as PAWK and PCWK, located in the Data
Memory.
PAPU4
PBPU4
PAC4
PBC4
PCC4
4
Bit
PCWK3
PAWK3
PAPU3
PBPU3
PCPU3
PCC3
PAC3
PBC3
3
PAWK2
PCWK2
PCPU2
PAPU2
PBPU2
PAC2
PBC2
PCC2
2
PAWK1
PCWK1
PAPU1
PBPU1
PCPU1
PCC1
PAC1
PBC1
1
HT45R22E
March 17, 2010
www.DataSheet4U.com
PCWK0
PAWK0
PAPU0
PBPU0
PCPU0
PAC0
PBC0
PCC0
0