DCMI

nakulrao · ‎2012-08-16

Posted on August 16, 2012 at 15:55

Hi everyone

I am currently using the DCMI on the STM3240G eval board. I can get images upto a resolution of 320x240. I wish to get images of 800x600. I have read that for this resolution the double buffer mode in DMA must be used. In this case is it like half the image is stored in one area and the other half is stored in a different area? Will I later have to combine them to get the complete image? Is there any other way to get images of high resolution?

Currently, I store the image in the SRAM and display it on a 320x240 LCD. Also I transfer it to the SD card so that I can view it on my laptop. For higher resolutions I wont be able to display them on the LCD. Is there any other method you would recommend to view these images or should I continue transferring them to the SD card?

Thanks in advance.

#double-buffer #dcmi #dma

Tesla DeLorean · ‎2012-08-16

Posted on August 16, 2012 at 18:26

The size of the image will be limited by the DMA transfer length (just shy of 256K as I recall for 32-bit), and the amount of available memory.

To display large images you could do some simple decimation, or some more complicated interpolation and scaling.

Tips, Buy me a coffee, or three.. PayPal Venmo
Up vote any posts that you find helpful, it shows what's working..

nakulrao · ‎2012-08-17

Posted on August 17, 2012 at 15:38

If I am not wrong you are talking about how to display high res images on the 320x240 LCD. thanks for the advice. I would appreciate if you could kindly shed some light as to how to use the double buffer in DMA. The reference manual and the examples have not been very helpful in this regard

nakulrao · ‎2012-08-18

Posted on August 18, 2012 at 18:00

Ok. So, after going through some amazing previous threads by clive1. BigM, AMSN and brad h I was able to get the double buffer working. I now get low res images.

But now I am facing another problem. My board came with OV2640. I am unable to increase the resolution. I tried several different settings. Either they have no effect, or they completely ruin the image. Has anyone done this before? I am looking forward to some replies.

Thanks in advance.

stbbrad3 · ‎2012-08-20

Posted on August 21, 2012 at 04:54

Sounds like you have made good progress!

I did a little bit of reading on an the OV sensor, but never implemented anything as I use an Aptina sensor. But if I remember correctly there is a bit more required for setting up for High Res. If you have read through the reference guide perhaps you wouldnt mind posting the register configurations for the OV sensor you are doing?