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Silicon Laboratories has introduced a universal serial bus (USB) touch screen bridge IC that is able to streamline the connection between touch controllers and host CPUs in computing systems with large displays. The new CP2501 USB touch screen bridge provides a programmable, easy-to-use USB interface for laptops, tablets, eBooks, mobile Internet devices (MIDs), kiosks, ATMs and other point-of-sale (POS) equipment with touch screen displays.
The CP2501 comes with pre-programmed touch screen USB interface software providing out-of-the-box USB support for large touch screens. Many touch screen systems in computing applications use a USB interface to communicate between the touch screen controller and host CPU. Most do not support USB directly, requiring a separate IC to bridge the communications gap. Developers tend to use a standard microcontroller (MCU) as a bridge chip and develop touch screen USB interface software or acquire it from resellers - a costly, time-consuming process.
The CP2501 touch screen bridge eases touch screen application development by providing pre-programmed firmware that enables developers to configure touch screen settings quickly and easily, streamlining software development and speeding time to market. The USB interface is Microsoft Windows 7 touch interface compliant and supports the USB human interface device (HID) digitizer class driver. The CP2501 also is supported by a GUI-based configuration wizard from Silicon Labs that allows developers to connect a touch controller to a USB system without developing customised USB firmware. Using the configuration tool, developers can create the firmware project, customise USB parameters and generate USB touch screen descriptors. A pre-programmed USB bootloader also supports easy in-system firmware updates.
"The CP2501 USB touch screen bridge uniquely addresses the growing application need to integrate large touch screens within computing systems - quickly, easily and with minimal USB software expertise," said Mark Thompson, vice president of Silicon Labs' Embedded Mixed-Signal products. "Leveraging Silicon Labs' leadership in high-performance, analog-intensive mixed-signal technology, the CP2501 is designed to accelerate the development of touch screen applications with Windows 7 compliant USB connectivity."
The CP2501 IC supports capacitive and resistive touch screen technologies and offers interfaces to the inter-integrated circuit (I2C), universal asynchronous receiver/transmitter (UART) and serial peripheral interface (SPI) buses. It features a high-performance 8051-compatible MCU core running at 48 MIPS with 53 kB of flash memory and 3.5 kB of RAM available for application software. The high-performance MCU core and generous memory provide ample headroom for developers to perform sophisticated algorithms such as noise filtering, position calculation and gesture interpretation. Sixteen GPIO pins enable developers to control LEDs and/or haptics, saving precious pins from the touch controller and reducing the processing burden on the host CPU.
