Atmel AT85DVK-07 Especificaciones descargar pdf (Pagina 127)

127

AT85C51SND3Bx

7632A–MP3–03/06

USB Host Operating Modes

Pipe Description 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.

Detach 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).

Power-on and Reset 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.

Host

Ready

Host

Idle

Device

disconnection

<any

other

state>

Device

connection

Clock stopped

Macro off

Device

disconnection

Host

Suspend

SOFE=1

SOFE=0

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Atmel AT85DVK-07 Especificaciones Pagina 127