Operation Explanation Of Usb Function - Fujitsu MB90335 Series Hardware Manual

CHAPTER 11 USB FUNCTION

11.4 Operation Explanation of USB Function

11.4 Operation Explanation of USB Function
The USB Function conforms to the USB (Universal Serial Bus) communication protocol
and supports basic protocol operations (handshake) by hardware. Consequently, only
processing communication data can provide the USB communication.
■ Operation of USB Function
The USB Function performs two-way packet transfer with a host controller that supports the USB protocol.
A host PC and its devices are connected and configured through enumeration. Then, communications based
on various types of transfers using device drivers are performed.
This section describes the operation of the USB communications between a host PC and its devices by
using enumeration as an example.
It illustrates the operations of registers and USB packets to understand the overview of USB
communication processing.
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Enumeration process
It is the first process that establishes the connection between a host PC and its device before the USB can
operate. The host PC examines which devices are connected to the USB bus by using USB control transfer
(USB transfer type). This uses EP0 (EndPoint0) out of six endpoints (as defined in the USB specifications)
(USB Specification).
When EP1 to EP5 are used, the following must be received on the USB bus.
1. USB bus reset
2. Address set by SET_Address
3. Configuration set by SET_Config
224 FUJITSU MICROELECTRONICS LIMITED
MB90335 Series
CM44-10137-6E