EAN-4000-OEM-MIPI-Cameras
© SightLine Applications, Inc.
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6
Troubleshooting
6.1
Determining Settle-cnt
In the 4000-OEM FPGA, a Ths-Prepare and THS-Zero are set. Each MIPI camera has a Ths-Settle. The
Ths-Settle (settle-cnt) is calculated in the 4000-OEM using the camera driver setting for
V4L2_CID_PIXEL_RATE.
If captured video looks incorrect or not capturing at all, adjust the V4L2_CID_PIXEL_RATE in the camera
driver so that a different settle-cnt is calculated.
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Questions and Additional Support
For questions and additional support, please contact
. Additional support documentation and
Engineering Application Notes (EANs) can be found on the
Applications website.
Appendix A - MIPI Camera Requirements for Connecting Commercial Cameras
Every commercial MIPI camera requires a Linux driver to work with any acquisition system. Camera
registers are vendor and model specific and must be configured over the MIPI I2C bus. Each camera
has different operating characteristics and requirements for proper operation. Currently a standard
interface for MIPI camera register setup and operations does not exist. For new MIPI cameras working
through configuration issues takes time. Reusing driver code from other cameras in most cases does
not work.
It is essential to address the Linux driver availability for new MIPI camera early in the process.
A1 Vendor Provided Driver / Interface
The vendor provided driver/interface does not use Snapdragon 820 ISP. A Linux driver must be
provided.
•
Linux driver with I2C register settings. Helpful when setting up the camera and turning on
streaming.
•
Linux driver settings must be for raw capture. The 4000-OEM only supports raw capture.
•
Linux driver to include V4L2_CID_LINK_FREQ and V4L2_CID_PIXEL_RATE settings.
•
SightLine recommends the device tree source file (overlay) for the DragonBoard 820c. This shows
data lanes, clock lanes, clock settings, and the I2C address of the sensor.
•
Four data lanes are available at the J9 connector on the 4000-OEM.
•
If available, a datasheet and register explanation for the camera.
•
Maximum of 750MHz pixel clock frequency (1.5Gbps / lane).
•
SightLine recommends the sensor have an ISP (Sony IMX sensors do not).
A raw capture using a sensor that does not have ISP will appear substandard. This would require
additional color 10-bit to 8-bit conversion using auto gain, brightness, and white balance
.
•
Format of the image - width, height, media bus format.
