Suitable method for implementing capsense??

cap sense key

Hi all,
I am using capacitor sensing technique for sensing user key press.
NE556 was connected in Astable mode and the capsense act as a capacitor in that. Hence the change in output frequency is monitored by a controller for detecting user key press.

But with this method, i couldnt get a consistant result!

i.e., for each key the frequency during key press varies.
also, if i place a 2mm thick glass sheet over capsense, i couldnt get a better frequency variation..
Hence it would be great if i could get some ideas on how it could be achieved.

i am also interested in a method where i could make the port logic level high/low for before/during touch. I am yet to get a method to achieve this. can i get a hint on how it need to be approached?

Suresh.

how to implement capsense

Why dont you use a Cypress Capsense Microcontroller. its very simple to implement Capsense Switches with them

If you aren't bent on making it yourself, check QProx touch switch IC products:

https://www.qprox.com/

Ken

krishna73v said:

Why dont you use a Cypress Capsense Microcontroller. its very simple to implement Capsense Switches with them

Click to expand...

for cost reasons. Thats why i look for low cost method.

Suresh.

Added after 6 minutes:

KMoffett said:

If you aren't bent on making it yourself, check QProx touch switch IC products:

https://www.qprox.com/

Ken

Click to expand...

Right now i am trying with LM567. I could also try any other suggestions i get here, so that i can analyse the performance of each.

Suresh.

hello everyone!

I am using CapSense with PIC24f16KA102.

when I interface two capsense with digital trim pot MCP4152, it was working well,
when I interfaced or wrote program for more then two capsense, the trim pot resistance is not changing accordingly.

I have 5 capsense in my circuit they are working I have tested with LCD interfacing

thank you

I have done it.
it was the chip errata problem.

now I have problem that if I put 1 mm acrylic on capsense it does not work..

any suggestion will be helpful

thank you