CX3 Can my firmware work at high speed(2.0)?

[roji_4156651]

My firmware works at super speed perfectly. Now I want to change to high speed for some reason. But I found that host software cannot receive any data.The CX3 firmware always reports DMA_RESET_EVENT. And I found that  CyU3PDmaMultiChannelCommitBufer reports error 0x41(CY_U3P_ERROR_INVALID_SEQUENCE).

The following figure is my sensor configuration in CX3 configuration tool. Can any guy tell me why it report such error? Can the following sensor configuration work at high speed?

[roji_4156651]

After change to USB2.0，the firmware frequently reports 0x41(CY_U3P_ERROR_INVALID_SEQUENCE). So increasing the DMA buffer or adding the code concerned in the KBA does not work.

[Rashi_Vatsa]

Hello Robin,

Please refer to this KBA  for reason of this error Invalid Sequence Error in Multi-Channel Commit Buffer - KBA218830

Practically USB 2.0  can support bandwidth of 25-30 MBps, the input video bandwidth from sensor in your case is 640*960*30*2(bytes/pixel) = ~ 36 MBps So you can either reduce the frames per second or video resolution foe seamless streaming in USB 2.0

Regards,

Rashi

[roji_4156651]

For my sensor,the pixel clock is 45MHz and the sensor MIPI pixel output is always RAW12. These parameters are fixed. That means the sensor MIPI output bandwidth is always 45M*12=540Mbps=67MBps no matter what the resolution is. Does CX3 have such constraint that the MIPI bandwidth must be less than USB bandwidth? If CX3 does not have such constraint, I think I can reduce the resolution and try USB2.0. Could you confirm this?

[Rashi_Vatsa · Accepted solution]

Hello Robin,

As you are having sensor output of RAW12 but the GPIF ibus width is 16 bits. The remaining 4 bits will be padded( either 0 or 1). If in your case the padding of 4 bits is done, the frame size wll increase by 4 bits /pixel. so frame size will be h_active *v_active*fps*2(bytes/pixel or 16 bits/pixel).

Yes, if the input bandwidth is more than what USB 2.0 can consume commit buffer, error 0x41(CY_U3P_ERROR_INVALID_SEQUENCE will occur.

so the video bandwidth (input from sensor) should be around 25 - 30 MBps

Regards,

Rashi