PYTHON25K Datasheet, PDF (30/87 Pages) ON Semiconductor – PYTHON 25K/16K/12K/10K Global Shutter CMOS Image Sensors

NOIP1SN025KA, NOIP1SN016KA, NOIP1SN012KA, NOIP1SN010KA
ADDITIONAL FEATURES
Multiple Window Readout
The PYTHON sensor supports multiple window readout,
which means that only the user−selected Regions Of Interest
(ROI) are read out. This allows limiting data output for every
frame, which in turn allows increasing the frame rate. In
global shutter mode, up to 32 ROIs can be configured.
y1_end
y0_end
y1_start
Window Configuration
Figure 26 shows the four parameters defining a region of
interest (ROI).
y0_start
y-end
ROI 1
ROI 0
y-start
ROI 0
x-start           x-end
Figure 26. Region of Interest Configuration
• x−start[6:0]
x−start defines the x−starting point of the desired window.
The sensor reads out 64 pixels in one single clock cycle. As
a consequence, the granularity for configuring the x−start
position is also 64 pixels. The value configured in the x−start
register is multiplied by 64 to find the corresponding column
in the pixel array.
• x−end[6:0]
This register defines the window end point on the x−axis.
Similar to x−start, the granularity for this configuration is
one kernel. x−end needs to be larger than x−start.
• y−start[9:0]
The starting line of the readout window. The granularity
of this setting is one line, except with color sensors where it
needs to be an even number.
• y−end[9:0]
The end line of the readout window. y−end must be
configured larger than y−start. This setting has the same
granularity as the y−start configuration.
Up to thirty−two windows can be defined, possibly
(partially) overlapping, as illustrated in Figure 27.
x0_start
x0_end
x1_start
x1_end
Figure 27. Overlapping Multiple Window
Configuration
The sequencer analyses each line that need to be read out
for multiple windows.
Restrictions
The following restrictions for each line are assumed for
the user configuration:
• Windows are ordered from left to right, based on their
x−start address:
x_start_roi(i) v x_start_roi(j) AND
x_end_roi(i) vx_end_roi(j)
Where j > i
Processing Multiple Windows
The sequencer control block houses two sets of counters
to construct the image frame. As previously described, the
y−counter indicates the line that needs to be read out and is
incremented at the end of each line. For the start of the frame,
it is initialized to the y−start address of the first window and
it runs until the y−end address of the last window to be read
out. The last window is configured by the configuration
registers and it is not necessarily window #31.
The x−counter starts counting from the x−start address of
the window with the lowest ID which is active on the
addressed line. Only windows for which the current
y−address is enclosed are taken into account for scanning.
Other windows are skipped.
Figure 28 illustrates a practical example of a
configuration with five windows. The current position of the
www.onsemi.com
30