ADNS-4000 Avago Technologies US Inc., ADNS-4000 Datasheet - Page 12

• Manufacturer Part Number: ADNS-4000
• Description: SENSOR OPTICAL MOUSE LP 8DIP
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-4000

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Synchronous Serial Port
The synchronous serial port is used to set and read pa-
rameters in the ADNS-4000, and to read out the motion
information. The port is a four wire serial port. The host
micro-controller always initiates communication; the
ADNS-4000 never initiates data transfers. SCLK, MOSI, and
NCS may be driven directly by a micro-controller. The port
pins may be shared with other SPI slave devices. When the
NCS pin is high, the inputs are ignored and the output is
at tri-state.
The lines that comprise the SPI port:
SCLK: Clock input. It is always generated by the master
(the micro-controller).
MOSI: Input data. (Master Out/Slave In)
MISO: Output data. (Master In/Slave Out)
NCS: Chip select input (active low). NCS needs to be low
to activate the serial port; otherwise, MISO will be high Z,
and MOSI & SCLK will be ignored. NCS can also be used to
reset the serial port in case of an error.
Chip Select Operation
The serial port is activated after NCS goes low. If NCS is
raised during a transaction, the entire transaction is
aborted and the serial port will be reset. This is true for all
transactions. After a transaction is aborted, the normal ad-
dress-to-data or transaction-to-transaction delay is still re-
quired before beginning the next transaction. To improve
communication reliability, all serial transactions should
be framed by NCS. In other words, the port should not re-
main enabled during periods of non-use because ESD and
EFT/B events could be interpreted as serial communica-
tion and put the chip into an unknown state. In addition,
NCS must be raised after each burst-mode transaction is
complete to terminate burst-mode. The port is not avail-
able for further use until burst-mode is terminated.
‘Smart’ LED Current Switching
ADNS-4000 is designed with ‘smart’ LED feature, an auto or
self-adjusting LED current switching between the low and
high current settings depending on the brightness of the
tracking surface. If the surface is suffi ciently bright to the
sensor, lower LED current will be selected. When tracking
on a darker surface, the higher current setting will be used.
This feature is one of the power saving features in this sen-
sor controlled by AUTO_LED_CTRL register (0x43).
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Power Management Modes
The ADNS-4000 has three power-saving modes. Each
mode has a diff erent motion detection period with its re-
spective response time to mouse motion. Response Time
is the time taken for the sensor to ‘wake up’ from rest mode
when motion is detected. When left idle, the sensor auto-
matically changes or downshift from Run mode to Rest1,
to Rest2 and fi nally to Rest3 which consumes the least cur-
rent. Do note that current consumption is the lowest at
Rest3 and highest at Rest1, however time required for sen-
sor to respond to motion from Rest1 is the shortest and
longest from Rest3. Downshift Time is the elapsed time
(under no motion condition) from current mode to the
next mode for example, it takes 10s for the sensor that is
in Rest1 to change to Rest2. The typical response time and
downshift time for each mode is shown in the following
table. However, user can change the default time setting
for each mode via register 0x0e through 0x13.
Another feature in ADNS-4000 that can be used to opti-
mize the power consumption of the optical mouse system
is the Motion Interrupt Output or MOTION pin (pin 3). It al-
lows the host controller to be in sleep mode (or lowest op-
erating current mode) when there is no motion detected
after some time instead of consistently be in active mode
and polling motion data from the sensor. When motion is
detected, the sensor will send the motion interrupt signal
through pin 3 to the controller to wake it up from sleep
mode to resume its motion detection routine for naviga-
tion position and direction update.
MOTION Detection Routine
Typically in the motion detection routine, MCU will poll
the sensor for valid motion data by checking on the MO-
TION_ST bit in MOTION_ST register. If MOTION_ST bit is
set, motion data in DELTA_X and DELTA_Y is valid and
ready to be read by the MCU.
Mode
Rest 1
Rest 2
Rest 3
Response Time
(Typical)
10ms
100 ms
500 ms
Downshift Time
(Typical)
<1s
9s
430s