[HeRos] Coming back with a working camera


Since Thursday night, kudly project was able to get a picture from the camera ov2640. As a consequence, I was under pressure. Quickly, I configured the camera and patched the DCMI driver (cf Julien’s posts) like the kudly project. With the logic analyzer, it seemed to work but I wasn’t sure. My biggest problem was : how to get the jpeg out of the serial port…

I used arch on the desktop computer in A406 and I was using Minicom to communicate through the serial port. Minicom is simple but not enough friendly (for me). Moreover, I was angry against arch since it always set the ttyPort with sudo permissions. After complaining to Alexis, he told me to look old mails with the keyword “udev”. And the magic was effictive,  I just had to add rules to udev to set the ttyACM0 port with no sudo permissions.

The first image was not get with mine computer but flo computer. On his mac, he used coolterm which allows to save/see the data in hexadecimal. Now, I ‘m using cutecom. I can see the JPEG file in hexa (beginning is \ff\d8 and the end is \ff\d9).

What is next ?

  • Be sure that the camera take new picture every time
  • Use the dcmi in continue mode in order to get all the pictures sending by the camera ( I will adapt the camera clock because now we get 28 fps and we just need 25 fps)
  • Use the DMA with two buffers : one is written by the DCMA and the second one is sending with the wifi and it is commuted every picture.
    I don’t have to cut a picture as the size in jpeg is very small (4-10 kb) and a buffer is bigger.
  • Sending the whole through the wifi (first test are encouraging)


Eric Masseran


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