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UVC Extension Unit Example | Cypress Semiconductor

UVC Extension Unit Example

Summary: 2 Replies, Latest post by mchambers on 10 Feb 2016 11:30 AM PST
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mchambers's picture
2 posts

Can anyone point me to an example of a UVC Extension Unit implementation in the firmware?

I would just like to implement a Sensor register read/write.

I think I understand modifying the UVC descriptor, but where does the code go?

Does it go in the callback code along with Brightness etc..?

If so, what is the request type etc.. so that I can differentiate it?

Thanks, I am a newbie here. I appreciate the help.




mady's picture
Cypress Employee
955 posts

For a sensor read/write for control purpose you need to use the Processing unit Descriptor. Please refer to the example project with AN75779 Application note.

In the cyfxuvcdscr.c file, in the processing unit descriptor, you will see that the brightness control bit is set. From this, the host Applicaiton (video player) understands that the device supports brightness control. When the brightness is adjusted in the video pleayer, the corresponding callback code is shown in the UVCHandleProcessingUnitRqts function in uvc.c file. In that function, you can see SensorGetBrightness () and SensorSetBrightness () functions which reads / writes sensor registers using I2C. 

Please refer this and implement controls in your application.


-Madhu Sudhan

mchambers's picture
2 posts

Madhu, Tanks for your response!

My question was about UVC extension unit which is different from the canned Brightness, Contrast, Hue Etc...

I am wanting to add custom vendor specific funtionality, say turn on test bars, for example.



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