PAW3601DH Datasheet, PDF (18/35 Pages) Pixart Imaging Inc. – laser diode form a complete and compact laser mouse tracking system

PixArt Imaging Inc.
PAW3601DH
CMOS Laser Mouse Sensor
7.2 Re-Synchronous Serial Interface
If the mouse controller and the mouse sensor get out of synchronization, then the data either written or read from
the registers will be incorrect. There are two different ways for re-synchronous serial interface.
z Re-synchronous serial interface using PD pin (see Section 7.2.1)
z Re-synchronous serial interface using watchdog timer timeout (see Section 7.2.2)
Note that “watchdog timer timeout” (see Section 7.2.2) function is disabled when the mouse sensor is in the
power down mode. If the user uses this function during the power down mode, it will get out of synchronization.
The mouse sensor and the mouse controller also might get out of synchronization due to following conditions.
z Power On Problem - The problem occurs if the mouse sensor powers up before the mouse controller
sets the SCLK and SDIO lines to be output. The mouse sensor and the mouse controller might get out
of synchronization due to power on problem. An easy way to solve this is to raise PD pin (see Section
7.2.1) or use watchdog timer timeout (see Section 7.2.2) for re-synchronous serial interface.
z ESD Events - The mouse sensor and the mouse controller might get out of synchronization due to ESD
events. An easy way to solve this is to raise PD pin (see Section 7.2.1) or use watchdog timer timeout
(see Section 7.2.2) for re-synchronous serial interface.
z USB suspend - Termination of a transmission by the mouse controller may be required sometimes (for
example, due to a USB suspend interrupt during a read operation). An easy way to solve this is to raise
PD pin (see Section 7.2.1) or use watchdog timer timeout (see Section 7.2.2) for re-synchronous serial
interface.
7.2.1 Re-Synchronous Serial Interface Using PD Pin
The mouse controller raises PD line to reach re-synchronous serial interface after an incorrect read. The mouse
sensor will reset the serial port but will not reset the registers and be prepared for the beginning of a new
transmission. Note that using “PD pin” to reach re-synchronous is quicker than using “watchdog timer timeout”.
PD
1us,min
SCLK
1
2
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
SDIO
Hi-Z
ADDRESS(R/W)
DATA
Figure 12. Re-synchronous Serial Interface Using PD Pin
7.2.2 Re-Synchronous Serial Interface Using Watchdog Timer Timeout
The mouse controller can toggle the SCLK line from high to low to high and wait at least t_SIWTT to reach re-
synchronous serial interface after an incorrect read. The mouse sensor will reset the serial port but will not reset
the registers and be prepared for the beginning of a new transmission.
t_{SIW TT}
SCLK
1
2
3
4
5
6
7
8
9
1
0
1
1
1
2
1
3
1
4
1
5
1
6
SD IO
t_RESYNC
1us, m in
H i-Z
ADDRESS
(R/W )
DATA
Figure 13. Re-synchronous Serial Interface Using Watchdog Timer Timeout
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PixArt Imaging Inc.
E-mail: [e-mail]
V2.2, Aug. 2007