The CP2501 device is a touch screen USB bridge that can be used to connect the touch screen controller with the host CPU. The CP2501 incorporates a highperformance MCU with a 48 MIPS 8051compatible core, 53 kB of userprogrammable flash memory and 3.5 kB of RAM. Unlike other USB microcontroller devices in the market, the CP2501 features preprogrammed USB touch interface firmware, which greatly simplifies USB touch screen product development. The Windows 7 touch interface compliant CP2501 device works seamlessly with the Windows digitizer class driver for touch screens and is supported by Silicon Labs' GUIbased configuration wizard. This deployment tool enables developers to easily and quickly connect their touch controller to a USB system without having to develop customized USB firmware, thus reducing time to market as well as the level of expertise required for USB interface development.
The CP2501 device features a USB 2.0compliant, fullspeed USB controller with an integrated fullspeed transceiver and onchip matching and pullup resistors. The integrated USB controller manages all data transfers on the USB bus, as well as command requests generated by the USB host controller. The user firmware uses the interface provided by the system firmware to initialize and communicate using the USB protocol. The CP2501 device also includes a USB bootloader to easily update user firmware. User code is required to enable the interface API to initialize the USB interface and send touch data to the host PC.
The CP2501 device supports three different serial interfaces for communicating with various touch screen controllers. The interface choice can be selected through the CP250x configuration wizard. The CP2501 device's UART interface consists of the UART_TX (transmit) and UART_RX (receive) data signals and is programmable to support a wide range of data formats and baud rates. The SPI protocol provides access to a flexible, fullduplex synchronous serial bus. SPI operates as a master device in 4wire mode. The optional slaveselect signal can be left floating when connecting to a 3wire SPI device. Additional GPIO pins can be used to select multiple slave devices in master mode. The CP2501 device's SPI interface consists of the SPI_SCLK (clock), SPI_MOSI (master out), SPI_MISO (master in) and SPI_NSS (slave select) signals and is programmable to support a wide range of clock speeds and configurations.