at85c51snd3 ATMEL Corporation, at85c51snd3 Datasheet - Page 127

• Manufacturer Part Number: at85c51snd3
• Description: At85c51snd3 Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

USB Host Operating Modes
Pipe Description
Detach
Power-on and Reset
7632D–MP3–01/07
For the USB Host controller, the term of Pipe is used instead of Endpoint for the USB
Device controller (see Figure 64). A Host Pipe corresponds to a Device Endpoint, as
described in the USB specification.
Figure 64. Pipes and Endpoints in a USB system
In the USB host controller, a Pipe will be associated to a Device Endpoint, considering
the Device Configuration Descriptors.
The reset value of the DETACH bit is 1. Thus, the firmware has the responsibility of
clearing this bit before switching to the Host mode (HOST set).
Figure 65 shows the USB host controller main states after power-on.
Figure 65. USB Host Controller Reset State Machine
USB host controller state after an hardware reset is ‘Reset’. When the USB controller is
enabled and the USB Host controller is selected, the USB controller is in ‘Idle’ state. In
this state, the USB Host controller waits for the Device connection, with a minimum
power consumption. The USB Pad should be in Idle mode. The macro does not need
to have the PLL activated to enter in ‘Host Ready’ state.
Clock stopped
Ready
Host
Device
connection
Macro off
SOFE=1
Device
disconnection
SOFE=0
Host
Idle
Suspend
Device
disconnection
Host
state>
other
<any
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