topic Re: capacitive touch of LPC845 in LPC Microcontrollers

capacitive touch of LPC845

1404387561 — Tue, 21 May 2019 01:26:48 GMT

I use the capacitive touch of LPC845. When the finger touches the connected wire, the touch event occurs. If the finger is close to the wire, or if the finger is blocked by an insulating object and touched again, it can not trigger the touch event. What's the matter?

Re: capacitive touch of LPC845

FelipeGarcia — Thu, 23 May 2019 21:16:46 GMT

Hello,

Please keep in mind that in this case the cover needs to be thin enough, and the metallic sensor needs to have a sufficient area for sensing.

Hope it helps!

Best regards,

Felipe

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Re: capacitive touch of LPC845

1404387561 — Sat, 25 May 2019 06:04:54 GMT

Thank you very much for your reply. I would like to ask you again if the contact surface is large enough and the lid is thin. Is it related to the capacitance connected to YH YL pins or what is the configuration of registers?

Re: capacitive touch of LPC845

FelipeGarcia — Wed, 29 May 2019 15:20:33 GMT

Hi,

The sensitivity will depend on your PCB sensor pad design. I recommend you to read the document below, there are some guidelines to increase sensitivity in chapter 2.3 and some tests were made with different kinds of interference affecting the sensor in chapter 5.

https://www.nxp.com/docs/en/application-note/AN12083.pdf

Hope it helps!

Best regards,

Felipe