The next task is to begin writing code to accomplish your specification. Also, they'll test your device to see how it meets all parts of the specification from power control to babbling. In most cases, the device is reset. In extreme cases, it is completely disconnected from the bus. Bulk transfers are the most common of all USB transfers and have a maximum packet size of 64 bytes.
Enumeration is done on initialization of the bus or on the addition of a new device.
There are a maximum of 127 devices on a USB bus. The descriptor informs the host as to the number of interfaces and the power requirements of the device as well as the device attributes. Control transfers set and retrieve important information concerning the device. For example, control transfers are used to get the descriptors and set the device address. Data packets are alternated between DATA0 and DATA1.