How can I output QVGA YUV with OV2640 of STM3220G-EVAL rev.C?

kamada · ‎2012-02-25

Posted on February 25, 2012 at 09:41

I can saw good picture on LCD, with OV2640 QVGA RGB565.

But I cannot get right picture with OV26740 QVGA YUV.

I tried the following action.

But I saw strange picture only.

Act 1. I got the register settings from the followin URL. But not good.

http://www.mail-archive.com/linux-media@vger.kernel.org/msg19236.html

Act 2. I got the register settings from stm32f4's sample source code.

stm32f4_dsp_stdperiph_lib\STM32F4xx_DSP_StdPeriph_Lib_V1.0.0\Project\STM32F4xx_StdPeriph_Examples\DCMI\Camera\dcmi_ov2640.c

function OV2640_JPEGConfig()

I remove the code of JPEG output.

Act 3. I contacted the distributor of OmniVision, and I got the datasheet of OV2640. But I could not get the setting of QVGA YUV. And the distributor said ''This sensor is EOL. So we couldn't support and couldn't send any other application note or technical documents.

Help me!

#stm32f2-ov2640

pobox2day · ‎2012-02-26

Posted on February 27, 2012 at 03:00

Hi Damien

The OV2640 datasheet is available on the web, so are some software and hardware application notes on the OV3640 which is very similar. The explanations on the register settings is the same in some cases with both sensors. You will find though that many of the register settings are undocumented and many examples of drivers on the web seem to be setting registers that are listed as reserved on the datasheet. So it's not so simple. This is also true of other vendors such as Aptina . I am probably going to stay with the RGB565 mode from the sensor and do the jpeg encoding in software, rather than try and get the jpg mode of the sensor to work. The DCMI also has a jpeg mode which you will need to set if you set up the camera for jpg output.

Ian

kamada · ‎2012-02-26

Posted on February 27, 2012 at 03:22

Hi Davies,

OV3640's register address is 16bit.

OV2640's register address is 8bit.

So their register settings are different.

I have to output by YUV.

I have not to output by JPEG.

I am developing the camera module that consist of OV7725 and STM32F2 that output JPEG.

So I wanted to connect OV7725 to STM3220G-EVAL.

But STM3220G-EVAL's DCMI connector is so abnormal that I couldn't connect them because cost and delivery.

OV7725 cannot output JPEG.

So STM32F2 has to encode JPEG by software.

OV7725 can output RGB.

But the processing time of software YUV->JPEG encode faster than RGB->JPEG.

And I want to confirm software before finishing up my developing board.

Regards,