16

write command may not complete correctly.

Next Read or

Write Operation

Data

Read Operation

Address

Address

SCLK

Figure 20. Timing between read and either write or subsequent read commands

7550 has time to prepare the requested data. The falling edge of SCLK for the first address bit of either the read or

operation.

Required timing between Read and Write Commands

There are minimum timing requirements between read and write commands on the serial port.

SCLK

Address

Data

t

SWW

Write Operation

Address

Data

Write Operation

Figure 18. Timing between two write commands

If the rising edge of the SCLK for the last data bit of the second write command occurs before the required delay

Address

Data

Write Operation

Address

Next Read

Operation

SCLK

t

SWR

Figure 19. Timing between write and read commands

Burst Mode Operation

Burst mode is a special serial port operation mode that may be used to reduce the serial transaction time for a motion

read. The speed improvement is achieved by continuous data clocking to or from multiple registers without the need

to specify the register address, and by not requiring the normal delay period between data bytes.

Burst mode is activated by reading the Motion_Burst register. The ADNS-7550 will respond with the contents of the

Motion, Delta_X_L, Delta_Y_L, Delta_XY_H, SQUAL, Shutter_Upper, Shutter_Lower and Maximum_Pixel registers in

that order. The burst transaction can be terminated anywhere in the sequence after the Delta_X value by bringing the

All data bits can be read with no delay between bytes by driving SCLK at the normal rate. The data are latched into the

output buffer after the last address bit is received. After the burst transmission is complete, the micro-controller must

NCS, even for a second burst transmission.

Motion_Burst Register Address

Read First Byte

First Read Operation

Read Second Byte

SCLK

Read Third Byte

Figure 21. Motion Burst Timing

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PixArt Imaging Inc.

PixArt Imaging Inc.

ADNS-7550 Integrated Molded Lead-Frame DIP Sensor