How to implement touchpad?

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Anonymous
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Hi, I want to use touchpad or button matrix to detect presence of object on a plane.

   

The design guide and component datasheet have few information about this.

   

So how could I set up a button matrix? How to physically connect each sensor widget? Is there any more detailed description about this component?

   

I attached my project with Tuner. 

   

PS: I often get I2C communication fail problem, any one knows why is that?

   

 

   

Thanks!

   

Good luck.

   

 

   

Song

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Anonymous
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You can search for CY3280 BMM Matrix kit in www.cypress.com to get the link to the kit webpage.

http://www.cypress.com/documentation/development-kitsboards/cy3280-bmm-matrix-button-module-kit

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rola_264706
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Have you checked these Documents

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VenkataD_41
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750 replies posted 500 replies posted 250 solutions authored

Hi Song,

   

1) You can find the layout files of the Cypress track pad shield from the following link. Please download "trackpad shield design files" from the link below which will give you the idea to build the layout for the trackpad.

   

http://www.cypress.com/documentation/development-kitsboards/cy8ckit-040-psoc-4000-pioneer-developmen... 

   

2) For implementing the button matrix please go the link below and download "CY3280_Board_design_files" to get an idea on layout design for button matrix. We recommend you to use CapSense CSX for implementing button matrix.

   

http://www.cypress.com/documentation/development-kitsboards/cy3280-bmm-matrix-button-module-kit​

   

Thanks and Regards,

   

Ganesh.

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Anonymous
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The last link gives 404 error.

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Anonymous
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You can search for CY3280 BMM Matrix kit in www.cypress.com to get the link to the kit webpage.

http://www.cypress.com/documentation/development-kitsboards/cy3280-bmm-matrix-button-module-kit

Anonymous
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Thanks for the link. I also found the "-BSM" kit which is more like what we need.

But I have a question here re layout. If I use double layer on pcb, could I remove the shield from the top layer and have it on the bottom layer instead? How would that affect performance ?

If I make a big hole in the center of the pad for lamp/led, should I artificially increase the top surface of the pad making it a square or rectangle with the same area as the round pad without hole in the middle ?

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Anonymous
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The Hatch pattern on the top layer is provided for noise immunity. If you remove the top hatch, you might see a slight increase in noise. I would strongly suggest you keep the hatch pattern and connect it to Shield if you need liquid tolerance, else you can connect it to device ground.

The maximum size of button should not be more than a typical finger diameter, therefore we recommend 15mm as the maximum button size.

You can increase the button diameter to maximum of 15mm in case you have a hole at the center of the key. Cypress's CapSense provides various tuning parameters to adjust the sensitivity even with a smaller button size.

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