The Zedboard is a powerful hobbyist system on chip with a ARM Coretx-A9 processor and a Xilinx FPGA built in. A great addon for the Zedboard is the OV7670 camera for image and video processing. The OV7670 can output 12 bit RGB in 640x480 resolution at 30 fps and can purchased for less than $20. The OV7670 camera used for this tutorial can be found here.
This tutorial will show you how to connect the OV7670 camera to the Zedboard and stream the camera through the VGA port on the board. The VHDL modules allow for easy interface to the frame information for further image processing.
A datasheet for the OV7670 is attached.
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Step 1: Import VHDL Code
The first step is to install Vivado 2015 on your computer and create an RTL project using the ZedBoard Zynq Evaluation and Development Kit. Next thing to do is to download all of the VHDL files attached to this step then add them to the project by clicking Add Sources under Project Management. If everything has been added correctly you should see the ov7670_top file under Design Sources and then all of the over various VHDL sources underneath it.
Step 2: Add Block Memory
The frame of the image is stored in a piece of block ram. To add the block ram to the project, click on the IP catalog under Project Manager and search for Block Memory Generator. The settings of the block ram can be seen in the images attached.
Step 3: Add Constraints File
To connect the FPGA to the camera a constraints file defining the inputs and outputs has to be declared. To add the constraints file, click on Add Sources then Add Constraints then import the XCF file connected. After the XCF file is imported the camera has to be connected. The XCF file lists all of the net names of the FPGA pins and the connections to the camera. You must connect the camera pins to the FPGA pins by using the PMOD/Pin table and the PMOD pinout.
Step 4: Generate Bitstream
Now the final step is to generate the bit stream by clicking Program and Debug then Generate Bitstream and connect the Zedboard to a monitor through the VGA port. After the bitstream has been generated and uploaded to the FPGA you should see the camera streaming on the monitor. Make sure to take the lens off the camera and to focus the camera!
The implementation guide attached describes the register settings in the camera to change various settings. To change the camera settings the ov7670_registers.vhd file must be edited. To decrease resource utilization, the camera can be changed to output only YUV and record the Y component which would store a greyscale version of the image which would reduce the memory block width from 14 bits to 8 bits.