Contents • • • • • • • • • • • • • • • What is USB? [ ] USB stands for 'Universal Serial Bus'. It is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication, and power supply between computers and electronic devices. USB was intended to standardize the connection of computer peripherals (including keyboards, pointing devices, digital cameras, printers, portable media players, disk drives and network adapters) to personal computers, both to communicate and to supply electric power. It has also become commonplace on other devices, such as smartphones, PDAs and video game consoles. USB has effectively replaced a variety of earlier interfaces, such as serial and parallel ports. USB flash drives are memory devices that are inserted and powered by USB ports. They store information and data that needs to be easily accessed. These devices are portable and convenient for people on the go. USB ports are a common necessity for students as well as business employees or personnel. In addition to convenience, they range in storage capacities from 1GB to 64 GB, so end users are able to store as much information as small computers. A USB Series “A” plug The hardware that contains the host controller and the root hub has an interface geared toward the programmer which is called Host Controller Device (HCD) and is defined by the hardware implementer. In practice, these are hardware registers (ports) in the computer. At version 1.0 and 1.1 there were two competing HCD implementations. Total Phase has bundled together a complete set of development tools and accessories that allow developers to erase, program, and verify Serial Flash memory chips. Thanks to Total Phase's Flash Center™ Software developers can quickly and easily program devices either stand-alone or in-system. PC-controlled programming via the E1 emulator, E20 emulator, E2 emulator, E2 emulator Lite, a serial or USB connection Interoperation with other software The efficiency of work can be improved by, for example, writing data to many boards consecutively and retaining logs of the written data in files. Usb spi flash programmer free download. FreeRTOS & libraries for AVR ATmega AVR ATmega port of freeRTOS A port of freeRTOS which. Usb Serial Flash ProgrammerCompaq's Open Host Controller Interface (OHCI) was adopted as the standard by the USB-IF. However, Intel subsequently created a specification they called the Universal Host Controller Interface (UHCI) and insisted other implementers pay to license and implement UHCI. VIA Technologies licensed the UHCI standard from Intel; all other chipset implementers use OHCI. The main difference between OHCI and UHCI is the fact that UHCI is more software-driven than OHCI is, making UHCI slightly more processor-intensive but cheaper to implement. The dueling implementations forced operating system vendors and hardware vendors to develop and test on both implementations which increased cost. During the design phase of USB 2.0 the USB-IF insisted on only one implementation. The USB 2.0 HCD implementation is called the Extended Host Controller Interface (EHCI). Only EHCI can support hi-speed transfers. Each EHCI controller contains four virtual HCD implementations to support Full Speed and Low Speed devices. The virtual HCD on Intel and VIA EHCI controllers are UHCI. All other vendors use virtual OHCI controllers. Class Codes [ ] The device descriptor of a USB device has a signature that tells what kind of device has been attached to the bus. This signature consists of class code, subclass code and protocol fields. Together, these identify what operating system driver should be used to communicate with the device. Additionally, each USB device interface descriptor contains the same signature fields. The interface signature allows multiple operating system drivers to simultaneously communicate with a single USB device (for example USB device with audio and video interfaces) and they also allow multiple instances of the same driver to communicate with separate interfaces of the same USB device (for example USB ethernet adapter with multiple ethernet ports) Devices that attach to the bus can be full-custom devices requiring a full-custom device driver to be used, or may belong to a device class. These classes define an expected behavior in terms of device and interface descriptors so that the same device driver may be used for any device that claims to be a member of a certain class. An operating system is supposed to implement all device classes so as to provide generic drivers for any USB device. Device class codes are decided upon by the Device Working Group of the USB Implementers Forum. Serial Flash ProgrammerIf the class applies to the entire device, the class code is assigned to the bDeviceClass field of the device descriptor, and if it is to be set for a single interface on a device, it is assigned to the bInterfaceClass field of the interface descriptor. It is also possible that multiple interfaces of the device are grouped by using an Interface Association Descriptor, in which case the class code is assigned to bFunctionClass fields of the descriptor.
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