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FX3 USB bidirectional traffic issues | Cypress Semiconductor

FX3 USB bidirectional traffic issues

Summary: 1 Reply, Latest post by Madhu Sudhan on 22 Oct 2016 01:57 AM PDT
Verified Answers: 0
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rgluskin_1832381's picture
1 post


I'm using Fx3 to stream UVC data successfully. I'm basing my program on Cx3UvcOV5640 sample.

In parallel I'm sending (very small and rare) control packets to the device on the EP0.

Sending these control packets sometimes sporadically cause the image to become vertically unsynchronized.

Sending a few more of the control packets sometimes sporadically restores the image to the normal state.


Digging a little deeper, I see that the function 
CyU3PDmaMultiChannelCommitBuffer returns 71 (CY_U3P_ERROR_INVALID_SEQUENCE) around the time where the issues begin.

Do you have an idea as to what might have gone wrong with the DMA, and how I should handle it ?




mady's picture
Cypress Employee
1058 posts


This error is caused when DMA Channel is trying to commit  a buffer when there are no free buffers available. The PC must comsume the buffers more quicker or the processing speed should be increased. The data coming from the senor might be too fast for FX3 to handle. Please create a Tech Support case so that our engineers would look into this issue and recommend enhancement to your code.


-Madhu Sudhan

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