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Document Feedback CMV12000 Functional Description Datasheet • PUBLIC DS000603 • v6 - 00 • 2023 -Sep- 22 84 │ 40 Interleaved HDR In this HDR mode, the odd and ev en columns of the image sensor will have a diff erent expos…
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CMV12000
Functional Description
Datasheet • PUBLIC
DS000603 • v6-00 • 2023-Sep-22
84 │ 39
The total frame time will be 3.3024 ms + 0.0301 ms = 3.3325 ms, which results in a frame rate of
300 fps.
If the exposure time is longer than the readout time the frame rate will depend on the exposure time.
Below you can see an overview of the frame rate in fps for a full resolution image and 64 outputs with
a 600 MHz LVDS input clock.
Figure 42:
Frame Rates vs Modes
Bit Mode
Normal
X&Y-Subs.
Binning
8
333
401
251
10
300
533
267
12
132
267
267
As binning is done in the readout circuit, the four binned pixels have to be sampled, causing a longer
readout time needed and a drop in frame rate. When using fewer outputs, the frame rate will improve
when using binning.
Number of Frames
When using internal exposure mode, the number of frames taken at each frame request can be
programmed. In external exposure mode, only one frame is taken each time or you can use
continuous mode.
Figure 43:
Number of Frames Setting
Reg. Name
Address
Bits
Default
Description
Number_frames
80
[15:0]
1
1 to 65535
7.4.3 High Dynamic Range Modes
The sensor has different ways to achieve high optical dynamic range in the grabbed image.
● Interleaved read-out: The odd and even columns have a different exposure time
● Multiple slope: Partial reset of the photodiode, within an exposure time, to reset the saturated
pixels
All the HDR modes mentioned above can be used in both the internal and external exposure time
modes.
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CMV12000
Functional Description
Datasheet • PUBLIC
DS000603 • v6-00 • 2023-Sep-22
84 │ 40
Interleaved HDR
In this HDR mode, the odd and even columns of the image sensor will have a different exposure time.
This mode can be enabled by setting the register in the table below.
Figure 44:
Interleaved HDR Settings
Reg. Name
Address
Bits
Default
Description
Exp_dual
70
[1]
0
0: HDR Off
1: HDR On
The surrounding system can combine the image of the odd columns with the image of the even
columns, which can result in a high dynamic range image. In such an image, very bright and very dark
objects are made visible without clipping. The table below gives an overview of the registers involved
in the interleaved read-out when the internal exposure mode is selected.
Figure 45:
Interleaved HDR Exposure Settings
Reg. Name
Address
Bits
Default
Description
Exp_time
71
72
[15:0]
[7:0]
1536
Sets the exposure time for the even columns.
Exp_time2
73
74
[15:0]
[7:0]
1536
Sets the exposure time for the odd columns.
When the external exposure mode and interleaved read-out are selected, the different exposure times
are achieved by using the T_EXP1 and T_EXP2 input pins. T_EXP1 defines the exposure time for the
even columns, while T_EXP2 defines the exposure time for the odd columns. See the figure below for
more details.
Figure 46:
Interleaved HDR with External Exposure
FRAME_REQ
T_EXP1
T_EXP2
Exposure time even columns
Exposure time odd columns
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CMV12000
Functional Description
Datasheet • PUBLIC
DS000603 • v6-00 • 2023-Sep-22
84 │ 41
When a color sensor is used, the sequencer should be programmed to make sure it takes the bayer
pattern into account when doing interleaved read-out. This can be done by setting the appropriate
registers to ‘0’.
Figure 47:
Interleaved HDR Color Mode
Reg. Name
Address
Bits
Default
Description
Color
68
[0]
1
0: Color sensor
1: Monochrome sensor
Color_exp
68
[3]
1
0: Color sensor
1: Monochrome sensor
Multiple Slope HDR
The CMV12000 has the possibility to achieve a high optical dynamic range by using a multiple slope
feature. This feature will partially reset those pixels, which reach a programmable voltage, while
leaving the other pixels untouched. This can be done 2 times within one exposure time to achieve a
maximum of three exposure slopes. See figure below for more details.
Figure 48:
Multiple Slope HDR
In the figure above, the red lines represent a pixel on which a large amount of light is falling. The blue
line represents a pixel on which less light is falling. As shown in the figure, the bright pixel is held to a
programmable voltage for a programmable time during the exposure time. This happens two times to
make sure that at the end of the exposure time, the pixel is not saturated. The darker pixel is not
Vhigh
Vtfl2
Vtfl3
Vlow
Total exposure time
Exp_kp2
Exp_kp1
Pixel reset Pixel sample