RTOS/TDA2P-ACD: FPD Link

Hi Stefan,

Are you operating with 4 lanes between UB953 & sensor, can you check if you are seeing this issue with either 3 or 2 or 1 data lanes?

Regards,
Sujith

Hi Stefan,

Is this resolved?

Regards,
Sujith

Hi Sujith,

I'm using IMX390 sensor and there is option to use 2 lanes or 4 lanes, but I don't have information which register needs to be changed in order to use just 2 lanes on sensor side. I don't have appropriate datasheet. Can you help me about that?

Best regards,
Stefan.

Hi Stefan,

Please check www.ti.com/.../ds90ub953-q1.pdf the feild CSI_LANE_SEL can be used to select the number of lanes. You probably will have check with Sony, for IMX390 for it's configuration

Regards,
Sujith

Hi Sujith,

Can you check this FPD Link filtar and confirm that everything is OK. Can you identify something that can cause interference?

Best regards,

Stefan.

Stefan,

Let me check with our hardware expert

Regards,
Sujith

Sujith,

Ok, thanks. Please note one more thing: If I use local GPIO on UB953 for taking sensor out of reset (set it to 1), I'm able to start sensor. But, If I use remote GPIO to control RESET on sensor from deserializer side, I2C writes often fails and I'm unable to start sensor. It seems like FPD link is broken in small amount of time and sensor is probably reset... This is probably same problem that causes video flickering.

Best regards,
Stefan.

Stefan,

The clock to UB953 is driven by pixel clock of the sensor?

Regards,
Sujith

Sujith,

At serializer side it's selected synchronous clock mode, so clock is passed from the deserializer to the serializer and sensor should use it as a reference clock. Register MODE_SEL (0x03) has default value.

Regards,

Stefan.

Hi Stefan,

Okay. When using remote GPIO, add a little delay and try accessing the sensor. Also what is the back-channel frequency that you are using.

Regards,
Sujith

Hi Sujith,

Back channel frequency is 25 Mbps. It's configuration from Vision SDK, from file iss_sensor_imx390.c.

Did you get some answer from your hardware expert about FPD Link filtar? Also, you can take a look at this thread:

There are more informations about this problem here (videos, images).

Best regards,

Stefan.

This schematic aligns with the recommended PoC filter components for DS90UB960-Q1 connection to DS90UB953-Q1.  Please see datasheet which is now available on TI.com.

Kind Regards,

Liam

Hi Liam, Sujith

Thank you on provided datasheet, this version has much more informations than version I have.

Also, I think problem with flickering is solved. All 4 ports on deserializer were enabled and I had only one camera. After I disabled ports that are not used (ports which don't have camera connected) back channel is stable. Can you help me to understand better why this happening, so I can close this thread. If back channel is not established on other enabled ports, could that couse some problems with back channel which has camera connected?

Best regards,

Stefan.

Hi,

If I enable only 2 RX ports and connect only 2 cameras I have strange behavior: Sometimes everything is ok, back channel is stable and I have clear images from both cameras, but sometimes back channel is unstable and there is flickering on video. To be more clear - if video is stable after board power on it will remain stable. Only after I reset the board and start use case again this problem can appear. Some suggestions?

Regards,
Stefan.

Hi Stefan,

This seems more of h/w issue, i will re-request our h/w expert to look at this.

Regards,
Sujith