ADNK-3043-ND24
2.4GHz RF Wireless USB Optical Mouse Designer’s Kit
Design Guide
Introduction
This design guide describes the design of a low power
consumption optical mouse using the Texas Instrument
MSP430F1222 microcontroller, the Avago ADNS-3040
optical sensor and a Nordic nRF2402 2.4 GHz transmitter. The receiver dongle is implemented with a Nordic
nRF2401 in conjunction with a Cypress CY7C63231 USB
controller. The document discusses the reference design
hardware and the rmware implementation. Included
in Appendix A is the schematic for this reference design
mouse. The software section of this document describes
the architecture of the rmware required to implement
the mouse functions. The MSP430F1222 data sheet is
available on the TI web site at www.ti.com. The ADNS3040 data sheet is available from the Avago web site at
www.avagotech.com. USB controller data sheet can be
found on the Cypress web site: www.cypress.com. The
Nordic transmitter and receiver data sheets are available
on www.nordicsemi.no
Key reference design objectives:
1. Highlight the low-power benet of the ADNS-3040
2. Demonstrate a design with a RF daughter board to
facilitate experimentation with dierent RF technologies
3. Feature a Flash-based development environment to
facilitate rapid rmware changes
Features
• Complete LED mouse reference design kit
• Windows® 98SE, Windows 2000 and Windows XP
compatibility
• USB 1.0 low-speed compliance
• User identity code to avoid conict with other de-
vices
• High reliability
• Smooth surface navigation
• Enhanced SmartSpeed self-adjusting frame rate for
optimum performance
• High speed motion detection up to 20 ips and 8 G
• 800 cpi resolution
• No mechanical moving parts
• A high data rate 2.4GHz RF link
• Transmission data rate up to 1Mbps
• 15 meters communication distance
• Self-adjusting power-saving modes for longest bat-
tery life
• Minimal number of passive components
RF Board
Left Button
Avago
ADNS-3040
Optical Mouse
Sensor
Wheel Button
Right Button
Z Optics
TI
MSP430F1222
Microcontroller
MISO
MOSI
SCLK
NCS
Control
and Data
MAX1722
Boost Regulator
Quadrature
Signals
Lens
Image
Array
LED
Lens
Surface
Shadow pattern
Reference Design Overview
The image-based optical mouse sensor takes snap shots
of the surface it is navigating on. It measures changes in
position by comparing the sequential images (frames) and
mathematically determines the direction and magnitude
of movement. The traditional duel-channel optical
encoder generates the quadrature Z-wheel movement
signals. This design guide illustrates the hardware connection of a LED-based optical mouse with standard conguration; as well as the rmware management and the
handling of the USB protocols. USB protocol provides a
standard way of reporting mouse movement and button
presses to the PC. The Windows HID driver interprets the
USB data and performs the cursor movements and mouse
clicks.
The functional block diagram of the reference design
mouse is shown in Figure 1. The optical sensor detects
the X and Y movements. An optical quadrature encoder
provides the Z-wheel movement. Each of the button
switches is pulled up normally and provides a Ground
when pressed. The MAX1722 boost regulator maintains
the 2.7 V operating voltage for the reference design
mouse from two regular AA Alkaline batteries in parallel.
Figure 1. ADNK-3043-ND24 Reference Design Mouse functional Block Diagram
Theory of Operation
Navigation Technology
The heart of the ADNS-3040 navigation sensor is a CMOS
image array. An LED and an optical system illuminate
the surface that the ADNS-3040 is navigating on. The
texture of the surface casts bright and dark spots forming
distinct images as the sensor is moved across the surface.
A Digital Signal Processing (DSP) engine and its built-in
algorithm evaluate these images and determine the
magnitude and direction of the movement. The motion
data is made available in the delta_X and delta_Y registers
for the system controller to retrieve. An extensive power
saving topology is implemented within the ADNS-3040
navigation engine. A Motion pin (output) is available to
act as the system interrupt. As long as there is no motion
the system can remain in Sleep mode allowing maximum
battery power saving. Based on the last detected motion
the ADNS-3040 navigation engine enters various power
saving modes when no new motion occurs. These power
saving features make the ADNS-3040 ideally for wireless
applications.
Figure 2. Illustration of Optical Navigation technology
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Z-Wheel
The motion of Z-wheel is detected using the quadrature
signal generated by optical sensors. Two phototransistors
are connected in a source-follower conguration forming
Channel A and Channel B. An infrared LED shines,
causing the phototransistors to turn on. In between the
phototransistors and LED is a pinwheel that turns on the
mouse ball rollers. The fan of this pinwheel is mechanically designed to block the infrared light such that the phototransistors are turned on and o in a quadrature output
pattern. Every change in the phototransistor outputs represents a count of mouse movement. Comparing the last
state of the optics to the current state derives directional
information. As shown in Figure 3. below, rotating the
wheel forward produces a unique set of state transitions,
and rotating the wheel backward produces another set of
unique state transitions.
Hardware Implementation
Optical Mouse Sensor
This reference design features the ADNS-3040 optical
navigation engine. It contains an Image Acquisition System
(IAS), a Digital Signal Processor (DSP), and a three-wire
Serial Peripheral Interface consists of the serial clock (SCLK),
the master-in/slave-out (MISO) and the master-out/slavein (MOSI). In addition a fourth signal, Motion, is an output
intended to act as an interrupt to the microcontroller
whenever the ADNS-3040 senses motion. When the mouse
is moved the ADNS-3040 alerts the system controller by
activating the Motion signal triggering an interrupt service
routine. At the same time the ADNS-3040 accumulates
the horizontal and vertical displacements (count per inch,
or cpi) in its Delta_X and Delta_Y registers respectively.
The ADNS-3040 deactivates the Motion signal as soon as
movement stops. The SmartSpeed technology automatically optimizes the frame rate by examining the acquired
images of the surface. It also manages the integrated LED
driver to coordinate with the shutter.
The system controller reads the motion information and
reports it to the PC to update the cursor position.
Figure 3. Optics Quadrature Signal Generation
Mouse Buttons
Mouse buttons are connected as standard switches. These
switches are pulled up by the pull up resistors inside the
microcontroller. When the user presses a button, the
switch will be closed and the pin will be pulled LOW to
GND. A LOW state at the pin is interpreted as the button
being pressed. A HIGH state is interpreted as the button
has been released or the button is not being pressed.
Normally the switches are debounced in rmware for 1520ms. In this reference design there are three switches:
left, Z-wheel, and right.
The advantages of using ADNS-3040 optical sensor are the
ecient power management, high tracking accuracy, and
ecient communications with the optical sensor via the
full duplex SPI port.
To learn more about sensor’s technical information, please
visit the Avago web site at http://www.avagotech.com
Microcontroller
The Texas Instruments MSP430 family of ultra-low power
microcontrollers consists of several devices featuring
dierent sets of peripherals targeted for various applications. The architecture, combined with ve low-power
modes, is optimized to achieve extended battery life in
portable measurement applications. The device features
a powerful 16-bit RISC CPU, 16-bit registers, and constant
generators that attribute to maximum code eciency. The
Digitally Controlled Oscillator (DCO) allows wake-up from
low-power modes to active mode in less than 6 µsec.
The specic device used in this reference design is the
MSP430F1222 with 28 pin to accommodate ample amount
of I/O. It is an ultra-low power mixed-signal microcontrollers with a built-in 16-bit timer, 10-bit A/D converter with
integrated reference and Data Transfer Controller (DTC),
and 14 (20 pin package) or 22 (28 pin package) general
purpose I/O pins. The MSP430x12x2 series microcontrollers have built-in communication capability using asynchronous (UART) and synchronous (SPI) protocols.
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Serial Peripheral Interface (SPI)
The MSP430F1222 provides a dedicated hardware-based
Serial Peripheral Interface (SPI). The three-wire interface
supports byte serial communication in either Master or
Slave mode. In this reference design the MSP430F1222
always acts as the master and initiates all SPI communications with external SPI device(s), in this case the ADNS3040 and the nRF2401.
Z-Wheel Quadrature Encoder
A standard two-channel, incremental optical quadrature
encoder and an IR LED provide the scroll wheel function.
The MSP430F1222 manages the IR LED directly. Since
achieving low-power consumption is one of the main objectives, the optical LED is only enabled when the MSP430
needs to read the output states of the optical quadrature
encoder to the MSP430 port pins while in ACTIVE mode.
The optical LED is pulsed on for approximately 40 µsec
every 2 msec while in ACTIVE mode to read the current
position of the scroll wheel, thus saving power since the
optical LED is only on for a duty cycle of 2%. The outputs
of the two-channel quadrature encoder are squarewaves
that are 90° out of phase. The phase relationship of these
signals encodes the directions of scroll wheel rotations.
Within the MSP430, an internal Quadrature Encoder Pulse
(QEP) state machine interprets these signals and increments or decrements a counter based on the direction
and movement of the scroll wheel.
Wireless RF Technology
In order to provide the maximum exibility the reference
design mouse utilizes two circuit boards. The main board
consists of the ADNS-3040 navigation sensor/LED, the
MSP430F1222 microcontroller, the scroll wheel and
button switches. A 10-pin header connects the main
board to the RF daughter card. The Nordic nRF2401 2.4
GHz transmitter and its associated circuit including the
antenna resides on the daughter card. The 10-pin header
provides the SPI, regulated Vdd and unregulated battery
voltage (for possible future applications). The nRF2402 is
a single-chip transmitter for the world wide 2.4-2.5 GHz
ISM band. The transmitter consists of a fully integrated
frequency synthesizer, a power amplier, a crystal oscillator and a modulator. The output power and channel are
programmed through the SPI. Chip Select (CS) is used to
enable the nRF2402 when the microcontroller is ready
to pass it the motion or button switch data. Once the
data has been loaded into its input buer the nRF2402
manages the transmission and returns to power down
mode to conserve battery power. Typical power consumption is 10 mA at -5 dBm of output power.
The nRF2402 has two transmit modes:
• ShockBurst
• Direct Mode
In this reference design ShockBurstTM is used to capitalize on its benet. It utilizes the on-chip FIFO to accept SPI
data at the microcontroller operating rate but transmit at
very high rate (up to 1 Mbps). The short transmission time
enables extreme power saving. For detailed description
of the ShockBurstTM technology please refer to: www.
nordicsemi.no/
TM
High-frequency PCB layout:
A well-designed PCB is necessary to achieve good RF
performance. A fully qualied RF layout for the nRF2402
and it’s surrounding components, including matching
networks for the antenna can be downloaded from:
www.nordicsemi.no
A PCB with a minimum of two layers including a ground
plane is recommended for optimum performance.
The nRF2402 dc supply should be well filtered and
decoupled as close as possible to the Vdd pins with high
performance RF capacitors. Specically a high-grade
SMD tantalum capacitor (e.g. 4.7 µF) should be used in
parallel with the smaller-value high-frequency bypassing
capacitors. The nRF2402 should have its own branch of
well-ltered supply voltage, routed separately from the
supply voltage for the digital circuitry.
Full swing digital signals should not be routed close to the
crystal or the power supply lines.
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HLMP-ED80-PS000 (LED)
ADNS-2220-001
ADNS-3040
Customer supplied
ADNS-3120-001
Customer supplied base
plate with recommended
alignment features per
IGES drawing
Some details on ADNK-3043-ND24
Sensor
Object Surface
Lens
2.55
0.10
To Disassemble the ADNK-3043-ND24 Unit
The ADNK-3034-ND24 reference design kit allows users
to evaluate the performance of the Optical Tracking
Engine (sensor, lens, LED assembly clip, LED) over a RF
connection. This kit also enables users to understand the
recommended mechanical assembly. (See Appendix C,
D, and E)
System Requirements
PCs using Windows 95/ Windows 98/ Windows NT/
Windows 2000 with standard 3-button USB mouse
driver loaded.
Functionality
This reference design is an optical mouse with three
buttons and a scroll wheel.
USB Operating Mode
The receiver dongle is hot pluggable into the USB port.
The PC does not need to be powered o when plugging
or unplugging the receiver dongle for the evaluation
mouse.
The ADNK-3034-ND24 comprises of the plastic mouse
casing, a main printed circuit board (PCB), lens, buttons,
and a 2.4 GHz RF daughter card, and a 2.4 GHz USB
receiver dongle. (See Figure 4.) Removing the screws
located at the base of the unit separate the top and the
bottom of the mouse casing. Removing the PCB assembly
from the base plate further disassembles the mouse unit.
Be careful with the battery terminals while separating the
PCB assembly with the bottom casing.
While reassembling the components, please make sure
that the Z height (Distance from lens reference plane to
surface) is maintain. Refer to Figure 5.
Figure 5. Distance from lens reference plane to surface
Figure 4. Exploded view of the ADNS-3040 optical tracking engine
Caution: The lens is not permanently attached to the sensor and will drop out of the assembly.
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