2 Replies Latest reply on Oct 26, 2017 1:55 AM by Madhu Lakshmipathy

    fx3 uvc with sensor ov7675 not working

    gordon.tsai_2774976

      Hi all

         I am working on CYUSB3KIT-003 kit with image sensor ov7675 currently, and using AMCap on PC

         I follow the instruction AN75779, and made some modify with the previous discussion

         Re: Cypress EZUSB FX3 to stream video from OV7670

         AN75779 modification - FX3 for streaming image sensor data

       

          Hardware setting:

          ov7675 is initialized by another device, so i2c function on fx3 is disabled

          only connect DQ[0-7]  PCLK  FV  LV to fx3

         since ov7675 default resolution is 640*480 so I connect the fx3 to usb 2.0 port on PC,

         according to the  AN75779, the uvc will switch to 640*480 automatically, and AMCap recognize this as well

       

        I enable the #define DEBUG_PRINT_FRAME_COUNT to check the status of frame receiving

        and using oscilloscope to check the FV and LV existing, and it does

        but i can't see any image on AMCap

       

        the debug info:

           most of the time:

           UVC: Completed 0 frames and 0 buffers

           UVC: Completed 0 frames and 0 buffers

           UVC: Completed 0 frames and 0 buffers

           UVC: Completed 0 frames and 0 buffers

       

          sometimes:

         Application Started

         UVC: Completed 0 frames and 0 buffers

         UVC: Completed 175 frames and 0 buffers

         UVC: Completed 363 frames and 0 buffers

         UVC: Completed 528 frames and 0 buffers

         UVC: Completed 727 frames and 0 buffers

         UVC: Completed 898 frames and 0 buffers

         UVC: Completed 1065 frames and 0 buffers

         UVC: Completed 1221 frames and 0 buffers

         UVC: Completed 1421 frames and 0 buffers

         UVC: Completed 1583 frames and 0 buffers

         DMA Reset Event: Commit buffer failure

         Application Stopped

       

        is anyone encounter the same problem?

        • 1. Re: fx3 uvc with sensor ov7675 not working
          gordon.tsai_2774976

          Hi all

            Finally I got it work. It turns out the PCLK signal problem. I just change a way to connect PCLK between sensor and FX3

            However I can't tell the different of PCLK between two connection ways on oscilloscope.

           

            By the way, during the debugging I add debug message in: uvc.c function CyFxUvcApplnDmaCallback()

          擷取.JPG

          which will result in system crash.

          • 2. Re: fx3 uvc with sensor ov7675 not working
            Madhu Lakshmipathy

            Hi,

             

            You are not commended to add Debug Prints in the DMA Callback for every buffer. It adds too much overhead. DMA Callbacks ger triggered more quickly than debug data is sent over UART,

             

            So, if you want to print statistics of buffers, you do it at certain intervals (for example, print after  every20 buffers or print at the last buffer of the frame (short buffer) .

             

            Regards,

            - Madhu Sudhan

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