Introduction to the HT82M35A-1002
The HT82M35A-1002 is designed as 3-key 3D PS/2 optical
mouse controller. It provides serial interface to access the
sensor ADNS-5020EN or compatible sensors. A 2MHz RC
oscillator is needed for system frequency with external
pull-high resistor (140kohm).
Serial Peripheral Interface (SPI)
The HT82M35A-1002 provides a SPI compatible interface.
The SPI circuit supports byte serial transfer in either
Master or Slave mode. The integrated SPI circuit allows
the HT82M35A-1002 to communicate with external SPI
compatible hardware, in this case the ADNS-5020EN.
Hardware Implementation
The standard hardware to implement a mouse is shown
in Figure 3. For X and Y movement, the optical sensor is
used. The Z- wheel movement is detected by mechanical
encoder that output quadrature signals. For each button
there is a switch that is pulled up internally by the built in
pull up resistors.
Left Button
ADNS-5020EN
optical mouse sensor
Wheel Button
Right Button
Z Optics
Holtek
HT82M35A-1002
microcontroller
PS/2 Interface
SDIO
SCLK
NCS
SCLK/SDATA
Avago
Figure 3. HT82M35A-1002 –ADNS-5020EN Optical Mouse Hardware Block Diagram
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