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Touchscreen MCUs support mutual-capacitance sensing

Posted: 29 Apr 2014 ?? ?Print Version ?Bookmark and Share

Keywords:Atmel? controller? touchscreen?

Atmel, while a name associated with MCUs and FPGAs, has also made huge leaps in touch technology for the large format screen space.

In fact, Atmel boasts a wide range of ultra-low-power single-chip touchscreen controllers for screens ranging from 1.5" to 15.6". Today, Atmel announced production of the mXT106xT2 family of devices. These devices include the high-end touchscreen features associated with state-of-the-art smartphone-sized products, but they target the larger format market with products whose screens are in the 7in to 8.9in range.

The mXT1066T2 and mXT1068T2 controllers support both mutual-capacitance and self-capacitance sensing. By intelligently switching back and forth between the two and using a hybrid approach, designers can achieve optimal power consumption and noise immunity, even in high humidity and moisture environments, while supporting bare finger and gloved operation.

Additionally, mXT1068T2 controllers supports hover operation in which the user's finger can be up to 20mm above the touch surface.

Atmel touchscreen controllers

Hover adds another dimension to the user-touchscreen interface by allowing the touchscreen to detect, track, and interact with a floating finger without physical contact. Hover technology is becoming more of a user requirement and allows product creators to provide more differentiated solutions.

Currently, only single-finger hover is supported, but one can easily imagine how useful this would be if using a tablet to read a recipe when one's hands are covered in food. In the future, multi-fingered hover control might allow the user to "grab" objects and rotate them.

Hover is one element in an increasingly sophisticated realm of human-machine interfaces (HMIs) that also include gesture recognition. In the not-so-distant future, people will interact with electronic systems using a mixture of voice control, gesture recognition, and touchscreens, including hover technology.

Atmel touchscreen controllers

mXT1068T2 controllers also support high-quality passive and active stylus control that provides a true pen-to-paper experience. Drawing Asian characters like Chinese pictograms, for example, requires a fine tip and multiple levels. When used with the active maXStylus, mXT1068T2 controllers can support a tip-size of 1mm and provide pressure-sensing up to 256 levels. This provides users with the ability to write on their touchscreens and capture even small characters with a paper-like experience.

In addition to the main touchscreen, many products also make use of buttons to facilitate additional HMI interactions and use-models. Historically, if these buttons were also required to offer touch control, then this would be implemented in firmware and would tie up some of the main screen's X/Y lines, thereby degrading its resolution.

Atmel touchscreen controllers

By comparison, the mXT106xT2 family features a peripheral touch controller (PTC) capability that enables capacitive sensing of up to 12 channels by means of a dedicated hardware block in the mXT chip.

The new devices in the maXTouch T Series are in production now, with an evaluation kit for the 8.3" screen size becoming available in May.

- Max Maxfield
??EE Times

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