ht82a836r Holtek Semiconductor Inc., ht82a836r Datasheet - Page 16

• Manufacturer Part Number: ht82a836r
• Description: Usb Audio Mcu
• Manufacturer: Holtek Semiconductor Inc.

Port A Wake-up Control Register -
PA_WAKE_CTRL
This register is used to select the edge type that triggers
the wake-up function on the Port A pins. If the configura-
tion options select some or all of the Port A pins to have
a wake-up function then this register can be used to se-
lect either whether the active edge is a negative or posi-
tive transition. Only Port A is allowed this selection.
Pulse Width Modulator Registers - PWM0, PWM1,
PWMC
The device 2 integrated Pulse Width Modulators. Each
one has its own independent register, known as PWM0
and PWM1. The 8-bit contents of each of these registers
define the duty cycle value for the modulation cycle of
the corresponding pulse width modulator. The PWMC is
the control register for the PWM functions and controls
the mode selection and on/off function.
A/D Converter Registers - ADRL, ADRH, ADCR,
ACSR
The device contains a single 6-channel 12-bit A/D con-
verter. The correct operation of the A/D requires the use
of two data registers, a control register and a clock
source register. There are two data registers, a high
byte data register known as ADRH, and a low byte data
register known as ADRL. These are the register loca-
tions where the digital value is placed after the comple-
tion of an analog to digital conversion cycle. The
channel selection and configuration of the A/D converter
is setup via the control register ADCR while the A/D
clock frequency is defined by the clock source register,
ACSR.
USB Registers
The device contains an internal USB port which is con-
trolled via several registers. These are used to setup the
USB operation, the external pins, error handling etc. As
this register list is too numerous to list here details can
be found in the relevant USB description.
PFD Registers - PFDC, PFDD
The device contains a fully integrated Programmable
Frequency Driver otherwise known as the PFD. Two
registers control the overall operation of the PFD to de-
termine the output frequency and the function en-
able/disable.
Other Registers
The device contains several other special function reg-
isters for control of various internal functions. As their
functional description is too detailed to be described
here their details will be provided in the relevant func-
tional description section.
Rev. 1.00
16
Input/Output Ports
Holtek microcontrollers offer considerable flexibility on
their I/O ports. With the input or output designation of ev-
ery pin fully under user program control, pull-high op-
tions for all ports and wake-up options on certain pins,
the user is provided with an I/O structure to meet the
needs of a wide range of application possibilities.
The microcontroller provides a maximum of 44
bidirectional input/output lines labeled with port names
PA, PB, PC, PD, PE and PF. These I/O ports are
mapped to the Data Memory with addresses as shown
in the Special Purpose Data Memory table. Seven of
these I/O lines can be used for input and output opera-
tions and one line as an input only. 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 address. For output
operation, all the data is latched and remains un-
changed 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, 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 selectable via
configuration options and are implemented using a
weak PMOS transistor.
Port A Wake-up
If the HALT instruction is executed, the device will enter
the Power Down 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 a logical transition on one of the Port
A~Port F pins from high to low. After a HALT instruction
forces the microcontroller into entering the Power Down
Mode, the device will remain idle or in a low-power state
until the logic condition of the selected wake-up pin on
Port A~Port F changes from high to low. This function is
especially suitable for applications that can be woken up
via external switches. Note that each pin on Port A~Port
F can be selected individually using configuration op-
tions to have this wake-up feature. Additionally Port A
pins have an additional selection allowing their wake-up
function to be either negative or positive edge triggered.
This option is provided using the PA_WAKE_CTRL reg-
ister. Only Port A pins have this feature, the wake-up
pins on the other ports are only negative edge triggered.
HT82A836R
March 20, 2008