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PSoC™ 4 Forum Discussions

JoJo_4453281
Level 1
Level 1

Hi all, I've got a pretty noobish understanding of the PCB world, but the various guides on it all have given me a pretty good understanding on capsense, enough to get started.

I'm currently trying to design a touchpad. It needs to be 30mm x 150mm and I've decided a 4x20 grid will do the trick (each block's diagnol length is roughly 7.5mm).

I'm currently very stuck on picking out a MCU. There seems to be a ton of options and I'm not sure exactly what I might need.

1. What is the best MCU to that has 48 capsense i/o pins for a 4x20 touchpad? (I am correct in assuming I need 48 capsense pins for a 4x20 trackpad I hope...)

2. What is the difference between capsense i/o and GPIO? On some MCU datasheets, they are listed as different things, but other documents seem to state you can use GPIO for capsense?

3. I'm very new to Eagle as well but I can figure that out thanks to Youtube tutorials... A few PSoC devices are there in my Eagle library by default, but I'm not sure if any of them will work in my case. Once I know which PSoC device I need, how do I find an Eagle library containing it?

4. Are there, by any chance, how-to videos or tutorials demonstrating the schematic/PCB design of a touchpad? Any examples I could take a look at, just to aid in the learning process?

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Hari
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750 replies posted 500 replies posted 250 solutions authored

Hi JoJo_4453281

For a 30mm x 150 mm, it is recommended to use 6x30 grid of diamond patterns. You can refer the Hardware files of CY8CKIT-041-41XX PSoC 4100S CapSense Pioneer Kit. The flex PCB design shows the touchpad layout that is recommended for best performance.

1. For a 6x30 touchpad, the GPIO required is only 36 (plus 2 pins for integrating caps if CSX is used). The recommended controller would be  PSoC 4100S Plus, as it offers the latest CapSense IP and provide the necessary GPIOs required. Please note however that the CapSEnse component limits each widget to have only 16 Tx sensors so two touchpad widgets would be required.

2. Any GPIO can be used as CapSense GPIO. The limitation on some controller was due to the limitation of certain pins being unable to connect to AMUXBUS and the latest devices do not have this limitation. Any GPIO in PSoC 4100S Plus can be configured as CapSense pin.

For an example of the layout, please refer the hardware design files present along with the 041-41XX kit. CY8CKIT-041-41XX PSoC 4100S CapSense Pioneer Kit

Best regards,

Hari

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Hari
Moderator
Moderator
Moderator
750 replies posted 500 replies posted 250 solutions authored

Hi JoJo_4453281

For a 30mm x 150 mm, it is recommended to use 6x30 grid of diamond patterns. You can refer the Hardware files of CY8CKIT-041-41XX PSoC 4100S CapSense Pioneer Kit. The flex PCB design shows the touchpad layout that is recommended for best performance.

1. For a 6x30 touchpad, the GPIO required is only 36 (plus 2 pins for integrating caps if CSX is used). The recommended controller would be  PSoC 4100S Plus, as it offers the latest CapSense IP and provide the necessary GPIOs required. Please note however that the CapSEnse component limits each widget to have only 16 Tx sensors so two touchpad widgets would be required.

2. Any GPIO can be used as CapSense GPIO. The limitation on some controller was due to the limitation of certain pins being unable to connect to AMUXBUS and the latest devices do not have this limitation. Any GPIO in PSoC 4100S Plus can be configured as CapSense pin.

For an example of the layout, please refer the hardware design files present along with the 041-41XX kit. CY8CKIT-041-41XX PSoC 4100S CapSense Pioneer Kit

Best regards,

Hari

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Thanks for the reply.

I'm pretty confident that the PSoC 4100S Plus will be the best PSoC device for my purposes. Thanks for clarifying the GPIO vs. Capsense pin i/o, and another look at the capsense design guide made me go duh, I would need number of pads + 2 because of how Tx and Rx work.

I'm still noobish to all of this, but I believe the next steps are designing a schematic and PCB layout in a CAD program, then getting it manufactured, then using PSoC creator to develop firmware?

What is the best way to proceed with designing a schematic and PCB layout for a touchpad with a PSoC 4100S Plus MCU? The first roadblock I've hit is that I can't seem to find a library containing the PSoC 4100S Plus in an Eagle library.

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Hari
Moderator
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750 replies posted 500 replies posted 250 solutions authored

Hi JoJo_4453281

We do not have library files in Eagle format. We have the library files for Altium, Allegro and pads. You can refer this link for details: https://www.cypress.com/cad-resources/psoc-4-cad-libraries

The same is discussed in the following thread: Best Method for Schematic & PBC Layout Design for CSX Capsense Touchpad

Thanks,

Hari

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Hi jojo_4453281,

A thought for a library source would be ultralibrarian.com .  Your part might be too new to already be there, if so they can make it for you for low cost.  If its been around a while, it may be there and if so its free.  Here is a link to an older PSOC 4 design that is free for download on that site.  Cypress Semiconductor CY8C4125AXI-483: Symbol, Footprint, 3D STEP Model | Ultra Librarian   Its worth a look and I would keep this site in the back of your mind for future need.

Regards,

Lynn

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