Specifications
53
Alvium CSI-2 Cameras User Guide V2.8.1
Exposure time and frame rates
Achieved values deviating from specified values
Values stated in the model specifications show the maximum available on an ideal
system, supporting a bandwidth of 1.051 Gbps per lane. Your individual setup may
affect available values such as for:
• Minimum and maximum exposure times and increments
• Maximum frame rates, including ROI frame rates
• Image resolution steps.
•
Image resolution steps
. Depending on the available increments, some
standard resolutions are not supported. For example, instead of 1,440 × 900
pixels for WXGA+, 1,440 × 904 pixels are available.
•
Minimum resolution
. Depending on the embedded board, minimum
resolution may be greater than stated in tables. For example, instead of
16 × 16 pixels, the minimum resolution available may be 256 × 32 pixels.
• We recommend you to set ROI values before you set values for Exposure Time,
because interdependencies between controls affect each other. See
changes by control interdependencies
CSI-2LaneCount and CSI-2ClockFrequency
Alvium cameras require higher bandwidths than supported by only one CSI-2 lane,
especially with low CSI-2 clock frequencies. We recommend you to do extensive
testing to find the best setup for maximum frame rates, regarding:
• CSI-2LaneCount
•
CSI-2 ClockFrequency (CSI-2 Clock)
.
Dropped frames or a viewer issue?
Alvium CSI-2 cameras are designed for a maximum bandwidth that does not
exceed board abilities. However, if your setup does not provide sufficient
bandwidth, frames are dropped. Even if bandwidth is sufficient, embedded boards
may not be able to display all images of an image stream. In this case, only the
display is affected but no dropped frames occur.
Frame rates with ROI/Cropping
ROI and Cropping work similarly: While ROI is typically used for
GenICam for CSI-2
Access
, Cropping is typically used for the
other access modes
. By using a reduced
area of the available sensor, the payload is reduced, increasing frame rates. This
user guide uses the term ROI.
The maximum frame rate which can be achieved depends on various values, such
as bandwidth, pixel format, exposure time, and ROI. Calculation of maximum
frame rates for different ROIs for Alvium CSI-2 cameras does not allow to give a
formula. Data is calculated for
