11

Power Management Modes

The ADNS-3530 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.

Mode

Response Time

(Nominal)

Downshift Time

(Nominal)

Rest 1

16.5 ms

237 ms

Rest 2

82 ms

8.4 s

Rest 3

410 ms

504 s

Motion Pin Timing

The motion pin is a level-sensitive output that signals

the microcontroller when motion has occurred. The mo-

tion 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-3530 will flash the LED only when needed.

Synchronous Serial Port

The synchronous serial port is used to set and read pa-

rameters in the ADNS-3530, and to read out the motion

information.

The port is a four wire serial port. The host microcon-

troller always initiates communication; the ADNS-3530

never initiates data transfers. SCLK, MOSI, and NCS may

be driven directly by a microcontroller. 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 mas-

ter (the microcontroller).

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 se-

rial 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 nor-

mal address-to-data or transaction-to-transaction delay

is still required before beginning the next transaction.

To improve communication reliability, all serial transac-

tions 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.

Write Operation

Write operation, defined as data going from the micro-

controller to the ADNS-3530, is always initiated by the

microcontroller and consists of two bytes. The first byte

contains the address (seven bits) and has a “1” as its MSB

to indicate data direction. The second byte contains the

data. The ADNS-3530 reads MOSI on rising edges of

SCLK.

PixArt Imaging Inc.

Low Power LED Integrated Slim Mouse Sensor

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PixArt Imaging Inc.