2008-03-31 06:28:31     MT9V022 / MT9V032

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2008-03-31 06:28:31     MT9V022 / MT9V032

Servaes Joordens (NETHERLANDS)

Message: 53360   

 

I use a micron cmos image sensor. I use the sensor in snapshot mode.

 

The problem I have is that every time that I do not trigger the sensor for a few seconds I next few captures give bad images.

 

The first capture gives a white image, the second a very noisy image (like a very heavy snowstorm), the third a less noisy image, and the fourth give a good image.

 

I disabled auto-gain and auto-exposure.

 

Does anyone have experience with this sensor in snapshot mode? How do I disable all automatic behaviour of this sensor?

 

Thanks in advance,

 

Servaes

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2008-04-01 05:55:45     Re: MT9V022 / MT9V032

Yi Li (CHINA)

Message: 53440    Are you using the mt9v022.c driver? What is your kernel version?

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2008-04-01 13:28:55     Re: MT9V022 / MT9V032

Servaes Joordens (NETHERLANDS)

Message: 53476   

 

No, I have my own driver. With I2C command I set the sensor into snap-shot mode with the described results.

 

Do you have experience with this sensor in snapshot mode?

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2008-04-01 14:44:28     Re: MT9V022 / MT9V032

Servaes Joordens (NETHERLANDS)

Message: 53482   

 

I looked into the driver you mentioned, but I could not find many register (through i2c) settings of the sensor. Do you allways use the sensor in default operating mode?

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2008-04-01 19:20:59     Re: MT9V022 / MT9V032

Frank Van Hooft (CANADA)

Message: 53499    How confident are you in your hardware? How you looked at each signal with a 'scope? There are a _lot_ of hardware possibilities that can result in noise in an image. For example, the CMOS sensor is a sensitive analog device, and any coupled noise (eg switch-mode power supply noise, clock feedthroughs, etc) via any of its signals, but particularly VCC, GND and its master clock, can show up in the image. The sensor is sensitive to the master clock in just about every parameter: clock frequency, duty-cycle, rise & fall times.

 

I presume you've got the sensor connected to the PPI port (ie you're not using the LVDS outputs of the sensor). Have you confirmed the polarity of the frame sync signals?

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2008-04-02 02:28:03     Re: MT9V022 / MT9V032

Yi Li (CHINA)

Message: 53506    For MT9v022, the driver does not has many settings.

We only tested a few sensors, see here: http://docs.blackfin.uclinux.org/doku.php?id=:frame_capture_device&s=camera.

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2008-04-02 03:21:28     Re: MT9V022 / MT9V032

Servaes Joordens (NETHERLANDS)

Message: 53509   

 

The signals are of good quality, we did check the hardware signals. We indeed use the PPI, I will check the polarity soon. After a few images every looks good: the image quality is excellent.

 

We were thinking about a reset problem (educated guess). When the image is not triggered for a long time and the reset is not 100%, the sensors will pick up small amounts of light and in the long run will saturate the sensor. It takes a few images to empty the sensors again.

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2008-04-03 10:50:55     Re: MT9V022 / MT9V032

Servaes Joordens (NETHERLANDS)

Message: 53606   

 

I solved the problem.

 

In snapshot mode, you have to set the simultanous_mode to sequential, otherwise it does not work correctly! This is an undocumented feature :-)  !

 

thanks for the help

 

Servaes

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