A touchy subject: the new maXTouch chip from Atmel
By Paul Ridden
September 16, 2009
Atmel has just announced that its highly anticipated maXTouch mXT224 capacitive touchscreen controller chip is now ready for production release. Atmel representatives are positively bubbling with excitement about this product, which supports an unlimited number of simultaneous screen touches, looks out for unintentional touches and delivers smooth visuals with refresh rates of up to 250Hz - all on one tough, tiny, low-power chip.
Touchscreens seem to be everywhere these days but a sometimes clunky and unresponsive user experience makes some of them more of a nightmare to use than a joy. Having 224 mutual capacitance nodes, Atmel claims that the mXT224 chip can accurately identify, track and report the locations of numerous simultaneous screen touches. This is achieved by processing multiple points where rows and columns intersect on a screen matrix all at the same moment, which delivers smooth movement on any location of the screen.
Refreshing the screen every 4 milliseconds, and having high signal-to-noise ratios, not only eliminates recalibration issues and ensures accurate and fast response times but also gives the new chip the ability to discern different kinds of screen touch (such as using a stylus, a finger or a finger nail), an industry first according to Atmel.
maXTouch technology also supports gestures, handwriting and shape recognition as well as full multi-touch zoom and rotate functionality on touchscreens larger than ten inches.
The power to ignore
A video demonstration on the company's website shows the sensors even picking up individual fingers from inside a ski mitten. Combining the chip's unlimited touch detection with advanced algorithms allows processing and rejection of unintentional touches.
So in the video example, even though the ski mitten is touching the screen at numerous points, only the pressure of the fingers within the mitten is recognized as valid action. The upshot of this could see an end to phantom pocket phone calls or accidental key activation by a stray digit or an ear or cheek inadvertently touching the screen.
Light on resources
Although programmable to scan at different rates, if set to 100Hz (for example) the 5mm by 5mm by 0.6mm AVR-based controller chip only takes about a millisecond to scan all the sensor nodes. As the chip only reports back to the host when an event is detected, it actually spends most of its time in idle or sleep mode. Amtel says that helps to make its power consumption about 10% less than others currently on the market.
"maXTouch provides capabilities and features not available in existing capacitive and resistive touchscreen technologies and expands the universe of user interface design possibilities," said Peter Jones, Managing Director of Atmel's Microcontroller Business Unit.
Coming soon to a screen near you
"Many of the world's largest touchscreen customers are moving rapidly to adopt maXTouch products and take full advantage of the technology feature set in their next generation products," according to Jones, so you may soon benefit from a more responsive, much improved tactile experience in the very near future.
This single chip touchscreen product is just the first in a family of maXTouch capacitive sensing controller solutions however, with additional maXTouch offerings to follow later this year and early next year.