UVC abnormally low frame rate

[KeWa_2323766]

I am working on a UVC application based on FX3 controller. There are 800x600 pixels/frame. The pixel depth is 3-byte, i.e 24 bits/pixel. I set the USB packet size to 1024 byte. Set packet number to be 25 per bulk. However, the frame rate it can reach at PC side is only 20fps, i.e. 800*600*3*20*8 bits/s= 230,400,000 bits/s.  

The transfer speed between FX3 and PC is tested using sample firmware image "USBBulkSourceSinkLED.img" and software tool "Streamer.exe". It can reach 442800k*8=3.5Gbps, which is far more than the UVC bit rate. The camera frame rate is measured by probing the frame valid signal from cmos sensor and it is actually 120Hz.  I need some help on the data loss between CMOS sensor and PC.

Thank you in advance.

[JeWa_3769446]

Hi,

This maybe a CMOS sensor timing problem.

You need to check your CMOS register value of exposure time and frame length line.

frame rate = vt_pclk / (frame length line * line length package)

Hope this will be helpful to you.

[KeWa_2323766]

Jewa,,

Thank you for your reply. I verified the sensor configuration and oscilloscope probed frame valid signal is of 120Hz. Is there any other possible  reason?

[KeWa_2323766]

Hi, can anyone help me with this problem?

Thank you in advance.

[YashwantK_46]

Hi,

Can you please let me know the following:

1.) H active

2.) H blanking

3.) V active

4.) V blanking

5.) Frame Rate

6.) PCLK

7.) Bits/ pixel

Can you please probe the FV and LV lines and share the oscilloscope trace?

Regards,

Yashwant

[KeWa_2323766]

Yashwant,

I would close this thread since I am working on the hardware fix now. I will revisit this thread or open another thread when I am able to probe these signals.

Thank you very much