21

Motion

Address: 0x02

Access: Read/Write

Reset Value: 0x00

Field Name

Description

MOT

Motion since last report

0 = No motion

1 = Motion occurred, data ready for reading in Delta_X and Delta_Y registers

PIXRDY

Pixel Dump data byte is available in Pixel_Dump register.

0 = Data not available

1 = Data available

PIXFIRST

This bit is set when the Pixel_Grab register is written to or when a complete pixel array has been read, initiating an

increment to pixel 0,0.

0 = Pixel_Grab data not from pixel 0,0

1 = Pixel_Grab data is from pixel 0,0

OVF

Motion overflow, ∆Y and/or ∆X buffer has overflowed since last report.

0 = No overflow

1 = Overflow has occurred

LP_VALID

Laser Power Settings

0 = Register 0x1a and register 0x1f or register 0x1c and register 0x1d do not have complementary values.

1 = Laser power is valid

FAULT

Indicates that XY_LASER is shorted to GND or VDD

0 = No fault detected

1 = Fault detected.

Data Type: Bit field

USAGE: Register 0x02 allows the user to determine if motion has occurred since the last time it was read. If the MOT

bit is set, then the user should read registers 0x03 and 0x04 to get the accumulated motion. Read this register before

reading the Delta_X and Delta_Y registers.

Writing anything to this register clears the MOT and OVF bits, Delta_X and Delta_Y registers. The written data byte is

not saved.

Internal buffers can accumulate more than eight bits of motion for X or Y. If either one of the internal buffers over-

flows, then absolute path data is lost and the OVF bit is set. To clear the overflow, write anything to this register.

Check the OVR bit if more than 4” of motion is accumulated without reading it. If bit set, discard the motion as errone-

ous. Write anything to this register to clear the overflow condition.

The PIXRDY bit will be set whenever a valid pixel data byte is available in the Pixel_Dump register. Check that this

bit is set before reading from Pixel_Dump. To ensure that the Pixel_Grab pointer has been reset to pixel 0,0 on the

initial write to Pixel_Grab, check to see if PIXFIRST is set to high.

Bit

7

6

5

4

3

2

1

0

Field

MOT

PIXRDY

PIXFIRST

OVF

LP_VALID FAULT

Reserved

Re-

served

NOTE: Avago Technologies recommends that registers 0x02, 0x03, and 0x04 be read sequentially.