Projected-capacitive touch controller detects and avoids EM interference

November 14, 2014 // By Graham Prophet
Enabling improvements in the speed, accuracy and EMI stability of self-service touchscreens, and adding to its range of durable, ultra-large format projected capacitive (p-cap) touch sensing products, Zytronic introduced the ZXY110.

The card is a high performance touch controller, a next-generation update of the ZXY100, using a 32-bit ARM Cortex M4 processor capable of running at speeds of 168 MHz enabling Zytronic's self-capacitive p-cap (PCT) sensors to claim new benchmarks in responsiveness and precision. The processor is accompanied by two ASIC devices which help minimise controller footprint, while maximising touch detection performance, even through cover glass thicknesses exceeding 10 mm.

The ZXY110 is offered in two different versions; the 32-input version covers PCT p-cap touch sensors with up to approximately 19 inch diagonals, while the 64-input version is suitable for PCT sensors with diagonals of between 19 inch and 46 inches. Connection with the PC is via a USB 2.0 interface.

Updating of touch event coordinates is carried out by the ZXY110 in less than 5 msec, resulting in a satisfying user experience. This product’s key attribute is proprietary new architecture and firmware providing resilience to electro-magnetic interference (EMI). This ability to combat EMI comes from the new touch controller’s 'smart’ frequency-scanning function - where, the operating frequency moves dynamically between 1.3 MHz and 2.5 MHz, seeking “white space” - spectrum free of electromagnetic interferers - noise that would otherwise prevent the detection of touch events. The board can detect new sources of noise that arise, and shift operating frequency to avoid them. A feature of the algorithm is that tracking or object dragging that is in progress during such a frequency transition, continues seamlessly.

Suitable for use with Windows 7,Windows 8 and Linux operating systems, this item of hardware is a plug play human interface device (HID). The touch controller may also be used in conjunction with Zytronic’s freely downloadable ZyConfig software tool, which enables touchscreen integrators to access and tune the controller’s firmware settings, should they wish.

To ease implementation, the ZXY110 shares the same mounting arrangement as the company’s ZXY100 touch controller. As a result it can be