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Forum: FPGA, VHDL & Verilog OV7670 camera in VHDL


Author: jeorges FrenchRivera (Company: xlue) (khal1985)
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Hi everyone,

I'm trying to interface an OV7670 Camera module with my DE0 nano baord.
I found an example in the hamster Wiki 
http://hamsterworks.co.nz/mediawiki/index.php/OV7670_camera
but I don't understand a file named ov7670_capture.vhd that capture the 
pixels.
I' like to ask if it's possible to take time to look at this file and 
explain me the functionality?

Thanks in advance.

BEST REGARDS,

Author: Lothar Miller (lkmiller) (Moderator)
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jeorges F. wrote:
> to take time to look at this file and explain me the functionality?
What don't you understand?
First thing is done resetting when vsync is 1.
Then follows a some waiting for href going to 1.
If that is the case a counter is incremented and according to the 
counters value some action is encountered.
The final step after calculating an address and data is to set the write 
enable to 1.

BTW:
I'm tending to say the code quality is poor. One hint for that is the 
handling of href_last:
The reset to 0 is nonsense:
href_last <= '0';
Because this line of code is always overridden by that one a few lines 
later:
href_last <= href;

And this is written by someone not knowing too much about unsigned or 
integer data types:
cnt <= std_logic_vector(unsigned(cnt)+1);

: Edited by Moderator
Author: jeorges FrenchRivera (Company: xlue) (khal1985)
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Hi Lothar,

Thank you very much for you answer. I understand better now.
There is another version more elegant ov7670_capture.vhd - Version 2.0 
at the end of the wiki page.
Best regards

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