Bridging the capacitive touch gap with more processing power

Capacitive touch, or capacitive sensing, is commonly used in applications that need human machine interfaces (HMI), proximity detection, fluid level monitoring, acceleration and/or displacement. The basic principal is simple: a change in the sensing environment has a measurable effect on an electric field about a capacitive electrode. This can be done by altering parasitic capacitance to the ground (self-capacitance) or by altering the mutual capacitive coupling between neighboring electrodes (mutual capacitance). This change is then measured and processed by the application processor.  As one could imagine, this presents a number of design challenges to the engineer:

  • What happens if the sensor(s) get wet?
  • How do we design around electrical field noise? 
  • How do we remain sensitive enough to detect through gloves or product housings, but not so sensitive that we detect false positives or lose resolution?

From ultra-low power devices providing portability on mobile platforms to deployment in hazardous environments, TI’s MSP430™ microcontrollers (MCUs) with CapTIvate™ touch technology has you covered with IEC61000-4-x noise immunity, the ability to reject moisture, and detect through gloves or even 60 mm thick glass overlays. To accommodate smarter and smarter devices, we can achieve more immersive interfaces with force touch and 3D gesturing on a myriad of different button, wheel and slider configurations, which are the highest resolution in the industry and configurable in under five minutes with CapTIvate Design Center

While MSP430 MCUs with CapTIvate technology are very capable application processors on their own, you can bolster your design’s performance by integrating a host processor. This opens the door to virtually limitless additional technologies, platforms and adaptability, all while operating a UI at very low power.

The SimpleLink™ MSP432P401R MCU makes for an excellent example as a host processor. As a 32-bit ARM® Cortex®-M4F MCU capable of speeds up to 48 Mhz with 256KB of flash, it is well equipped for larger or  or  intensive applications. The SimpleLink MSP432™ MCU is also in its wheelhouse when it comes to resolution, with two onboard 32-bit timers and a 14-bit analog-to-digital converter (ADC) that’s arguably as valuable as the processor itself. Eight Enhanced Universal Serial Communication Interfaces (eUSCIs, four A’s and four B’s) accommodate communication with a large count of external devices. Add to that TI’s DSP, Graphics, and Driver Libraries and TI-RTOS support, MSP432 MCU offers development of powerful software with multitasking capabilities, all while maximizing both power and CPU efficiency.