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Data output from OV7670

Former Member

Hi All.

 

I have been trying to get some useful data from the OV7670 camera module but it seems that it is not outputting the correct data. I have been using this code: https://github.com/ComputerNerd/ov7670-no-ram-arduino-uno and everything seems fine from a software point of view but what I am getting out is not as expected. With the lens covered I should get a stream of repetitive data like [0,80,0,80,0,80....] but I dont regardless of whether it is covered or not. I have tried various register settings and still no joy. Even with default register settings I should be able to see a basic image. I have also viewed the data from the device on a logic analyzer and it is clear that the data is random. The pic below is the camera module output data with the lens covered and it can be seen that the data is totally random.

 

image

 

Anyone know why this is happening or has seen it before?

 

Thanks,

 

Mark.

  • 0 in reply to jc2048

    That's the problem no matter what coding I use the, 16 bits representing the pixel looks wrong. It is more that likely that I have set up the registers wrong and by what I have read online many others have had difficulties with them to. According to the following page the default format is YCbCr422, Embedded Programmer: Hacking the OV7670 camera module (SCCB cheat sheet inside) so even before I set the registers I should recieve the following to represent a black image [0,80,0,80,0,80....]. If it's wrong an the registers have to be set accordingly my question is: does anyone out there have any experience setting up the registers?

  • 0 in reply to Former Member

    Hi Mark,

     

    I've not used the OV7670 but have used a different part from the same mnfr. It is likely the registers may have some similarity.

    The link I mentioned earlier has the source code, so you could check the registers and compare with the OV7670 datasheet and try to create a list

    of registers and values that you will need to configure. Or, you might need to talk to the mnfr and ask them for configuration values, usually

    they will have this information.

    The link you provided shows that the person was using it with an STM processor, not Arduino, and he mentions that data rate by default (no configuration)

    is VGA, which is very high for a small microcontroller. So I suspect your Arduino Uno is skipping lines, possibly pixels too (and this is inline with the

    findings from the colour bar data you plotted).

  • 0 in reply to shabaz

    I am not really concerned with the arduino and what its doing. The data from the the actual pins of the device as viewed on an oscilloscope and logic analyzer are not as they should be. The only thing that is not really ideal is the clock input. Perhaps this is causing the device to behave improperly. Anyway I will be parking this for a while, I got a different camera with usb and works fine.

     

    Thanks

     

    Mark.