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Zybo Z7-20 Pcam 5C Demo with YCbCr422/RGB565


Takeshi

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Hi there,

I would like to ask about Zybo Z7-20 Pcam 5C Demo FPGA Design.

Pcam 5C demo says it supports only RAW image sensor output format. 

https://reference.digilentinc.com/learn/programmable-logic/tutorials/zybo-z7-pcam-5c-demo/start

I would like to evaluate YCbCr422 and RGB565 format of Pcam 5C(OV5640 can output those formats).

So would like to know if the D-PHY IP in the demo FPGA design can be used for YCbCr422 and RGB565 fomrat or not.

The MIPI CSI2 RX IP also.

Please see the attached block diagram.

Does anybody know it?

If it's impossible, could you tell me the reason too?

 

Regards,

Takeshi

Zybo_Z7-20_Pcam5C_Demo_Design.GIF

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Hi @Takeshi,

Its my understanding the the MIPI-2 hardware can work with both the YCbCr422 and RGB565 formats.

As describe in the copied text above, the Digilent Pcam-5C IP Core will not work with the CbCr422 and RGB565 formats and will only output raw data.

It looks like the two options available to use the YCbCr422 and RGB565 formats are as follows: 

1) Pay a license fee to acquire MIPI CSI-2 IP that is designed to work in FPGAs

2) Develop the hardware and software from scratch (custom IP Core). This requires a large time investment from someone with advanced skills. It also requires access to information that is not accessible to most, including closed specifications and datasheets.

I have not worked with YCbCr422 and RGB565 formats through a MIPI-2 port. Unfortunately, we would not be very helpful with creating a custom IP Core for using the Pmod Pcam-5C and the YCbCr422 and RGB565 formats.

thank you,

Jon

 

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Hi @jpeyron

Thank you for your answer and suggestions.

I understand the Digilent Pcam-5C IP Core will not work with the CbCr422 and RGB565 formats.

I'll consider various ways to evaluate CbCr422 and RGB565 here.

Thank you for your support.

I'll close this question.

Regards,

Takeshi

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Hi @Takeshi,

I am under the understanding the the MIPI-2 PHY can the YCbCr422 and RGB565 formats.  In the reference manual for the Pcam-5C here under software support (text linked below) it describes why we did not facilitate these formats and are using raw data.

Spoiler

Image sensor break-outs such as the Pcam 5C can only be controlled by an SoC with a MIPI CSI-2 controller in hardware and using them requires complicated software that properly configures the controller and the sensor. When trying to implement a method of using such a break-out with an FPGA host, there are two realistic options:

Pay a license fee to acquire MIPI CSI-2 IP that is designed to work in FPGAs. Typically this will provide a very robust solution and good software support, including embedded Linux drivers. The licensing fees are steep for these, and can be cost prohibitive to many. The source code is also often encrypted, so it can not be studied for educational purposes.

Develop the hardware and software from scratch. This requires a large time investment from someone with advanced skills. It also requires access to information that is not accessible to most, including closed specifications and datasheets.

To solve this problem, Digilent has created a set of open source Vivado IP cores that work with the Pcam 5C on FPGA and Zynq host boards. In order to achieve this in a practical manner, some short-cuts have been taken that limit this IP from functioning as robustly as some of the licensed solutions that are available. Also, the software paired with the IP does not currently take full advantage of all of the OV5640's features, which has some affect on the produced image quality. Digilent will continue to work to improve this IP, and encourages others to do the same by contributing to this open source project.

thank you,

Jon

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Hi @jpeyron,

Thank you for answering my question.

I understand that the MIPI-2 PHY can the YCbCr422 and RGB565 formats.

Does that mean I can use the same source code(register settings) for the MIPI-2 PHY regardless formats?

And  could you tell me if the LINK(MIPI CSI-2 RX) can the YCbCr422 and RGB565 formats?

Regards,

Takeshi

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