Is it possible to interface OV7670 module and avr directly?

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Guys,

Can I interface OV7670 module with AVR microcontroller directly ?
This is the module :
[url]http://www.aliexpress.com/store/...
[/url]Any links or experiences about it ?

Thanks

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How do you plan to use it with an AVR? The data rate will be too high (and memory requirements too large) to use it for any live video with an AVR, as far as I can see.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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ka7ehk wrote:
How do you plan to use it with an AVR? The data rate will be too high (and memory requirements too large) to use it for any live video with an AVR, as far as I can see.

Jim


easy test for capturing picture display on LCD

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Then take a look at these numbers:

1) Data rate from the device
2) number of 8-bit bytes per frame

Now, ask yourself:

1. :What am I going to do with those bytes?
2. Is there enough time available to do it?

Answering those 4 questions will give you your answer of whether or not it will work.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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1. :What am I going to do with those bytes?
Display the bytes from VGA cam to my LCD

2. Is there enough time available to do it?
I have no idea, may be there is

1) Data rate from the device
2) number of 8-bit bytes per frame
I need to check for OV7670 datasheet, any clues or comparison with other VGA modules ?

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The existing designs use a video ram to cope with the data rate. Jim's questions were rhetorical. Had you done some basic research, you would've known the answer already.

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Indeed, the questions were rhetorical. But, they are questions that anyone who wants to use a low speed MCU with video needs to answer. However....

One of the output formats of the cam module is VGA. Why does it even need to go through the MCU?

Configuration control is through an I2C (TWI) interface. The MCU does not even have to touch the video.

So, yes, it looks to me like it will work. But you still have a LOT of home work to do.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Adafruit has a jpeg cam that has NTSC video on the yellow wire and rx and tx serial on the green and white wires ttl level serial to grab a jpeg compressed frame in either 640x480 or half of that or half of that again.

Imagecraft compiler user

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But, they are questions that anyone who wants to use a low speed MCU with video needs to answer.

But the OP said nothing about video, only capturing picture display. If it is a single frame, then I believe that it can be done with that module.

Regards,
Steve A.

The Board helps those that help themselves.

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Yep. That's why I mentioned the Adafruit jpeg cam.

Imagecraft compiler user

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Here's the datasheet, which parameter should I see ?
thanks

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Koshchi wrote:

But, they are questions that anyone who wants to use a low speed MCU with video needs to answer.

But the OP said nothing about video, only capturing picture display. If it is a single frame, then I believe that it can be done with that module.

That's right, so the function of MCU is init the color LCD and VGA sensor, after that, display the VGA sensor result to LCD, that's it, even if it's possible I'll use my AT89S52, because that's the free board available now...hehe....it's only for a test, nothing fancy

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anyway, what's the function of FIFO AL422? what's the different if I don't use it ?
Is it some kind a temporary storage for OV7670 sensor ?
comparison :
without FIFO :[url]
http://www.ebay.com.au/itm/40047...

With fifo:
http://www.ebay.com.au/itm/120861276110?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649
Thanks
:)

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The point of Jim's questions were for you to understand that a vga frame takes X amount of bytes. Off the top of my head you have 640 * 320 = 204k assuming 256 level color. Your AVR does not have that kind of storage. Then there's the data rate - 204K times say 30 frames a second. The AVR cannot sustain that data rate. That is why you need the video fifo chip - it has the storage and can accept the data rate. The AVR can read the frame byte by byte at it's leisure and copy it to the display.

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Thanks for the explaination Kartman...

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bianchi77 wrote:
anyway, what's the function of FIFO AL422? what's the different if I don't use it ?

Dangerous Prototypes

OV7670 image sensor data capture with Atxmega32E5 without using external FIFO

December 8, 2014

http://dangerousprototypes.com/2014/12/08/ov7670-image-sensor-data-capture-with-atxmega32e5-without-using-external-fifo/

With current configuration, this system sends 20FPS 80×60 grayscale image data over 3Mbaud serial stream.

"Dare to be naïve." - Buckminster Fuller

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1.5 years late Mr G...... wink

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly