The USB software developer kit for ST's 32-bit ARM-based STR7 and STR9 microcontroller families is aimed at simplifying the implementation of embedded software for the utilisation of the USB interface standard. Both families include many variants with USB ports, alongside a broad range of other standard interfaces. The developer kit, downloadable from ST's website, supports STR71x and STR91x devices with USB, as well as the recently announced STR75x family. It allows software development for all the USB transfer types and includes an implementation of DFU (Device Firmware Update) to provide the capability to update system firmware through the USB interface. The kit also includes a «Virtual COM" demo (CDC class) to emulate the classic RS232 interface on USB, for users that want to retain legacy software. Also included in the software kit are a library of drivers and demonstrations of each transfer type. An HID (Human Interface Device) mouse/joystick driver demonstrates fast-response interrupt transfers; high-speed bulk transfers are illustrated with a mass storage application; and guaranteed speed isochronous transfers are supported with a voice/speaker/microphone demonstration.
