29

Field Name

Description

MOT

Motion since last report or PD

0 = No motion

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

Reserved

Reserved for future

FAULT

0 = No fault

1 = Fault detected

OVFY

Motion overflow Y,

∆Y buffer has overflowed since last report

0 = No overflow

1 = Overflow has occurred

OVFX

Motion overflow X,

∆X buffer has overflowed since last report

0 = No overflow

1 = Overflow has occurred

Reserved

Reserved for future

Reserved

Reserved for future

RES

Resolution in counts per inch

0 = 400

1 = 800

Notes for Motion:

1. Reading this register freezes the Delta_X and Delta_Y register values. Read this register before reading the Delta_X and Delta_Y registers. If

Delta_X and Delta_Y are not read before the motion register is read a second time, the data in Delta_X and Delta_Y will be lost.

2. Agilent RECOMMENDS that registers 0x02, 0x03 and 0x04 be read sequentially.

3. Internal buffers can accumulate more than eight bits of motion for X or Y. If either one of the internal buffers overflows, then absolute path data

is lost, and the OVFX or OVFY bit is set. These bits (OVFX and OVFY) are cleared once some motion has been read from the Delta_X and Delta_Y

registers, and if the buffers are not at full scale. Since more data is present in the buffers, the cycle of reading the Motion, Delta_X and Delta_Y

registers should be repeated until the motion bit (MOT) is cleared. Until MOT is cleared, either the Delta_X or Delta_Y registers will read either

positive or negative full scale. If the motion register has not been read for a long time, at 400 cpi it may take up to 16 read cycles to clear the

buffers, at 800 cpi, up to 32 cycles.

4. FAULT is a sticky bit that is cleared by reading the Motion register. It signifies that an LED fault has occurred since the last time the motion

register was read. Once an LED fault has cleared, the hardware will drive the LED normally.

80

81

FE

FF

00

01

02

7E

7F

-128

-127

-2

-1

0

+1

+2

+126

+127

MOTION

DELTA_X

Bit

76

5

4

32

10

Field

Data Type: Eight bit 2‘s complement number.

USAGE: X movement is counts since last report. Absolute value is determined

by resolution. Reading clears the register.

Delta_X

Address: 0x03

Access: Read

Reset Value: 0x00