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24
Motion
Access: Read
Address: 0x02
Default Value: 0x00
Bit
Field
7
6
5
4
3
2
1
0
MOT
Reserved
LP_Valid
OVF
Reserved
RES1
Fault
RES0
Data Type
:
Bit field.
USAGE: Register 0x02 allows the user to determine if motion has occurred since the last time it was read. If so, then
the user should read registers 0x03 and 0x04 to get the accumulated motion. It also tells if the motion buffers have
overflowed, if fault is detected, and the current resolution setting.
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. Avago Technologies RECOMMENDS that registers 0x02, 0x03 and 0x04 be read sequentially. See Motion burst
mode also.
3. 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. This bit is 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 long time, at 400 cpi it may take up to 16 read cycles to clear
the buffers, at 2000 cpi, up to 80 cycles. Alternatively, writing to the Motion_Clear register (register 0x12) will clear
all stored motion at once.
Field Name
MOT
Description
Motion since last report
0 = No motion
1 = Motion occurred, data ready for reading in Delta_X and Delta_Y registers
This bit is an indicator of complementary value contained in registers 0x2C and 0x2D.
0 = register 0x2C and 0x2D do not have complementary values
1 = register 0x2C and 0x2D contain complementary values
Motion overflow,
Y and/or
X buffer has overflowed since last report
0 = no overflow
1 = overflow has occurred
Indicates that the RBIN and/or XY_LASER pin is shorted to GND.
0 = no fault detected
1 = fault detected
Resolution in counts per inch (cpi). Resolution values are approximate.
LP_Valid
OVF
Fault
RES1, RES0
Cpi Bit2(RES1) Bit0(RES0)
400 0 0
800 0 1
1600 1 0
2000 1 1
Please see register 0x0a to set cpi