Multi-touch added to resistive touchscreens
R Colin Johnson, EE Times -- EDN, January 9, 2012
PORTLAND, OR—As touch-mania swipes across all markets, many applications look to upgrade to multi-touch but can't afford the high price of capacitive touchscreens. Now automobiles, appliances, medical devices, and low-end smartphones can retrofit multi-touch gestures to existing resistive-touchscreen designs, or create inexpensive alternatives to capacitive touchscreen products, by merely upgrading their controller-chips to Freescale Semiconductor Inc's new Ready-Play solution. The new Xtrinsic smart controller provides multi-touch gesture recognition for any standard 4- or 5-wire resistive touchscreen plus handles up to four capacitive touchpads.
"As tablets become more popular, the capacitive touchscreen business has been growing by over $200 million [per year, see figure], but the resistive touchscreen market has been growing at almost the same rate [$167 million]," said John Weil, global business manager for industrial MCU solutions at Freescale. "Adding a resistive touchscreen is a quick and inexpensive way to enrich existing and new applications in medical, consumer, automotive and other markets."
Capacitive touchscreens get all the glamour, since they are used on tablets, but markets for both resistive and capacitive touchscreens grew by at least 20 percent in 2011. Source: IHS iSuppli.
Using proprietary algorithms, and some analog hardware tricks, the new Xtrinsic CRTouch chip provides on-chip state-machines that can recognize slides, two-finger pinches for zooming in and out, as well as multi-finger rotations on standard resistive touchscreens. The controller chip also manages up to four capacitive touchpads for realizing keypads, rotary dials and linear sliders.
"We believe that the CRTouchB12 is the industry's first single-chip controller to offer both gesture recognition on standard resistive touchscreens, as well as capacitive touch sensing," said Weil.
Freescale is aiming the new controller chip at human-machine interface applications which eliminate the need for keyboards for all types of applications-from point-of-sale terminals to automotive dashboards to low-cost netbooks and mobile handsets-as well as in applications where users must wear gloves (medical/security/harsh-environments).
As a part of Freescale's Ready Play solutions, the CRTouch chip offers turn-key software integration with both Android and Linux operating systems. The 5×5-mm 32-pin QFN package also offers configurable screen resolution and optional calibration and pressure detection for stylus input to resistive touchscreens.
Freescale claims to have the first controller (center) that recognizes multi-touch gestures on standard resistive screens, as well as manage up to four capacitive-touch pads (right), shown here on a reference design board.
