IAR Systems has launched a USB stack that works with the IAR PowerPac RTOS and file system to offer the benefits of an easy-to-use USB interface to developers using IAR Embedded Workbench for ARM. This new addition to the company’s integrated middleware portfolio is particularly suitable for use in portable devices that need a convenient connection to a PC, such as digital cameras, MP3 players, modems or PC keyboards.
The IAR PowerPac USB stack is pre-configured and – when programmed using IAR Systems’ build tools, RTOS and file system – includes everything necessary to add a fully-working USB interface to an ARM device. The USB stack is designed to work on any ARM-powered embedded system with a USB device controller, and with a fast processor such as ARM7 is capable of transfer rates of up to 1MB/s on USB 2.0.
IAR PowerPac USB consists of three layers: a driver for hardware access, the USB core and a USB class driver or bulk communication component. The communication classes offered by the board support packages include bulk, Human Interface Device (HID), Mass Storage Device (MSD) and Communication Device Class (CDC) types, which suit most popular ARM devices and applications.
The bulk driver makes it simple for developers to optimise software rapidly for an embedded device such as a printer that communicates with a PC via USB, allowing usage of the full bandwidth of the USB bus. The MSD driver enables the use of an embedded target device such as a digital camera or USB stick as a USB mass storage device, which can then be plugged in and used in the same way as an conventional disk drive, with support already built into most computer operating systems. The CDC driver offers the capability to convert the target device into a serial communication device that is recognised by the host as a serial interface or virtual COM port, a mode of operation applicable to devices such as modems or telephone systems. The HID class driver is used for target devices that interact directly with, and take input from, humans – for example a keyboard, mouse, or gamepad. The device will be recognized by most computer
