The ADNS-3000 can be set to Power Down mode by writing
0x02 to register 0x0d to disable the sensor. In addition,
the SPI port should not be accessed during power
down. Other ICs on the same SPI bus can be accessed,
as long as the sensor’s NCS pin is not asserted. The table
below shows the state of various pins during power down.
To exit Power Down, write 0x5a to register 0x3a to reset
the sensor in order to wake it up. A full reset will thus be
executed. Wait tWAKEUP before accessing the SPI port. Any
register settings must then be reloaded.