PixArt Imaging Inc.
ADNS-3090 High-Performance Optical Mouse Sensor
Frame Capture
To read a single frame, read a total of 900 bytes. The next
636 bytes will be approximately 2/3 of the next frame.
The first pixel of the first frame (1st read) has bit 6 set to
1 as a start-of-frame marker. The first pixel of the second
partial frame (901st read) will also have bit 6 set to 1. All
other bytes have bit 6 set to zero. The MSB of all bytes is
set to 1. If the Pixel_Burst register is read past the end
of the data (1537 reads and on) , the data returned will
be zeros.
This is a fast way to download a full array of pixel values
from a single frame. This mode disables navigation and
overwrites any downloaded firmware. A hardware reset
is required to restore navigation, and the firmware must
be reloaded afterwards if required.
To trigger the capture, write to the Frame_Capture
register. The next available complete 1 2/3 frames (1536
values) will be stored to memory. The data are is retrieved
by reading the Pixel_Burst register once using the normal
read method, after which the remaining bytes are clocked
out by driving SCLK at the normal rate. The byte time
After the download is complete, the micro-controller
must raise the NCS line for at least t
to terminate
BEXIT
burst mode. The read may be aborted at any time by
raising NCS.
must be at least t
before the data is ready, it will return all zeros.
. If the Pixel_ Burst register is read
LOAD
Alternatively, the frame data can also be read one byte at
a time from the Frame_Capture register. See the register
description for more information.
exit burst mode
≥
4μs
tBEXIT
NCS
pixel dump reg read
address
frame capture reg
address
frame capture reg write
MOSI
SCLK
address
data
enter burst
mode
≥10μs
soonest to begin again
tCAPTURE
tSRAD
tNCS-SCLK
>120ns
tLOAD
10μs
tLOAD
10μs
≥
≥
≥
50μs
MISO
P1
all MSB = 1
P0
P899
see note 2
P0 bit 6 set to 1
Notes:
1. MSB = 1 for all bytes. Bit 6 = 0 for all bytes except pixel 0 of both frames which has bit 6 = 1 for use as a frame marker.
2. Reading beyond pixel 899 will return the first pixel of the second partial frame.
3. t
≥
10μs + 3 frame periods.
CAPTURE
4. This figure illustrates reading a single complete frame of 900 pixels. An additional 636 pixels from the next frame are available.
Figure 24. Frame capture burst mode timing
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
20
PIXART [ PIXART IMAGING INC. ]
