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PSoC™ 5, 3 & 1 Forum Discussions

Anonymous
Not applicable
        Hi,   
   
I am wondering if I can use capsense if it is not located on the same pc board. For instance if I have a keypad that is external to the main pc board that contains the capsense ic, can I just run the capsense wires to my keypad buttons only? Will it work if the capsense chip is not directly mounted on the keypad?   
   
Does anyone have any examples they can show or discuss?   
   
Thanks in advance.   
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4 Replies
JamesD_81
Employee
First like received Welcome!
Employee

Thanks for your inquiry.

I just wanted to respond and let you know I'm working on getting the correct answer to your question and to see if we have some examples for you. Didn't want you to think I was ignoring you .

Thanks!
Jim

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Anonymous
Not applicable
        Any information yet?   
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Anonymous
Not applicable
        You would need to shield the wires, as they would become capsense elements. There is a shield electrode, and it would have to surround the wires. Co-ax is the extreme, a wire wrapped around (might) work. Depends on the application, and how far away the sensors would be...BUT with the small size of the part, why not place it near the capsense pads, and communicate serially (uart or i2c) back to another "main" processor.   
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pushekm_21
Employee
10 likes received 5 likes given First like received
Employee
        Using wires running on a different board will increase the parasitic capacitance which in turn will reduce the sensitivity and will be more susceptible to noise. As suggested use shielded wires and try keeping the wires as short as possible and don't run any communication tracks closer to those wires. This can cause false detection. Also place a series resistor on the capsense lines of 560 ohm closer to the capsense IC.   
   
Regards   
Pushek   
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