PIC16F1455 mTouch

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PIC16F1455 mTouch

Post by qwertymodo » Sun Apr 20, 2014 5:05 pm

I've recently become interested in capacitive touch sensing, and having looked around for hardware I could use, I came across Microchip's mTouch library for PIC microcontrollers. The Microchip website's parametric search tool lists the PIC16F1455 as being mTouch compatible, but the mTouch Library (as well as the MLA legacy release) doesn't seem to have any support for it. Has anybody used the capacitive touch sensors in the 16F1455? I would love to build a USB HID class device with capacitive touch, and the 1455 (or 1459, if you want more touch channels) looks like it would be perfect for the job. I've already used the 16F1455 in a few USB projects, and it's possible to get it functioning as a USB device with nothing more than a pair of ceramic capacitors.

Also, if anybody has done capacitive touch sensor design before, I also have a design question regarding board layout. I'd like to have a touch-wheel with a center button, like on an iPod, but with the center button being a touch sensor. Will running a trace under the wheel to reach the center button cause too much cross talk when touching the wheel above or near that trace? I'll probably just be using standard 1.6mm FR4.

I already have the USB code figured out from my other work with the 16F1455, using the FOSS M-Stack rather than Microchip's proprietary USB stack. If I can't get the mTouch library working on this chip, I may just look for a 3rd-party solution, or else just a reference or application note on using the module so I can write my own from scratch and stay away from Microchip's library licensing entirely.

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