Power management modes
The ADNS-3040 has three
power-saving modes. Each
mode has a different motion
detection period, affecting
response time to mouse
motion (Response Time). The
sensor automatically changes
to the appropriate mode,
depending on the time since
the last reported motion
(Downshift Time). The
parameters of each mode are
shown in the following table.
Motion Pin Timing
The motion pin is a level-
sensitive output that signals
the micro-controller when
motion has occurred. The
motion pin is lowered
whenever the motion bit is set;
in other words, whenever there
is data in the Delta_X or
Delta_Y registers. Clearing the
motion bit (by reading Delta_Y
and Delta_X, or writing to the
Motion register) will put the
motion pin high.
LED Mode
For power savings, the LED
will not be continuously on.
ADNS-3040 will flash the LED
only when needed.
Mode
Rest 1
Rest 2
Rest 3
Response Time (nominal)
16.5 ms
82 ms
410 ms
Downshift Time (nominal)
237 ms
8.4 s
504 s
Synchronous Serial Port
The synchronous serial port is
used to set and read
parameters in the ADNS-3040,
and to read out the motion
information.
The port is a four wire serial
port. The host micro-
controller always initiates
communication; the ADNS-
3040 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 tri-
stated.
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 address-to-data or
transaction-to-transaction
delay is still required before
beginning the next transaction.
To improve communication
reliability, all serial
transactions should be framed
by NCS. In other words, the
port should not remain
enabled during periods of non-
use because ESD and EFT/B
events could be interpreted as
serial communication 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 available for
further use until burst-mode is
terminated.
11
AGILENT [ AGILENT TECHNOLOGIES, LTD. ]
