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Topic: Get the oscillator output (Read 2058 times) previous topic - next topic

djoko49

Hello,
I'm a newbie with the Arduino product and I would like to interface a camera OV9560 with a Arduino Duemilanove card. I need to send a to the Camera a clock and I would like to take it from the Arduino card. Could you please help me?


Grumpy_Mike

So what frequency does your camera need. Without that it is imposable to help.
Also are you sure? I have never come across a camera that needs this. What sort of camera are you using?

You are not thinking of transferring images are you?

Grumpy_Mike

OK now done a bit of searching. This appears to be a web cam with a USB connection, so this is not possible to interface with the arduino in a number of ways:-
1) You can't connect USB devices to it, the arduino is not a host.
2) There is not enough memory to put the image in to.
3) The data comes out too fast fro the arduino to handle.

djoko49

The camera is an Omnivision OV9650.
The camera is piloted with an SCCB bus (like I2C) and a parralel 8 bytes data bus to take datas.
I don't want to transfert them, I just want to save snapshot) on a sd card (that can be considered as transfer :))
Why you don't think it is possible.

djoko49

I don't want the USB feature.
Looks like it could be done.

http://www.jrobot.net/Projects/AVRcam.html

Grumpy_Mike

#5
Dec 01, 2010, 05:32 pm Last Edit: Dec 01, 2010, 05:38 pm by Grumpy_Mike Reason: 1
Quote
Why you don't think it is possible.


Please read my reply again especially point 3.

We get this all the time here, some people accept it and others argue but nobody has done it. Can you find an example on google?

You will see that the link you posted uses two processors and does not store the image.

djoko49

OK I understand that, the thing is that I look into the camera datasheet that we could divide the input clock with a register configuration so that the pixel 8 bits datas are not sent too fast.

Grumpy_Mike

Quote
the thing is that I look into the camera datasheet

So look again and you will see there is a minimum clock signal frequency, this minimum is still too fast for the arduino.

gardner

There appears to be a scalar to control the speed of the pixel output clock.  If the main clock was borrowed from an Arduino's 16Mhz one, you could get the pixels to fall out as slow as 250Khz.  You could possibly read them in at that rate -- just.

There is not going to be enough memory to hold anything like a whole frame in RAM.  And writing to the SD is not fast enough to keep up with the 250KHz clock rate of data coming out of the camera.

So what you would have to do is read the image in pieces.  Wait for a frame boundary, count through the bytes to some preset point, read the next chunk of bytes into RAM -- maybe 512 bytes or a K, then discard the rest.  Append the bytes to the SD file, go back and start over.  You will wind up with a frame saved on the SD that is assembled out of multiple input frames.

It won't be easy.

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