AT90SCR100 datasheet(209/433 Pages) ATMEL

209 / 433 page

209

TPR0327AY–SMS–30Jan09

AT90SCR100

Figure 17-4.

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.

17.5.2

Power-on and Reset

The next diagram explains the USB host controller main states on power-on:

Figure 17-5.

USB SCI states after reset

USB Host controller state after an hardware reset is ‘Reset’. When the USB Host controller is

enabled, 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.

The Host controller enters in Suspend state when the USB bus is in Suspend state, i.e. when the

Host controller doesn’t generate the Start of Frame. In this state, the USB consumption is mini-

mum. The Host controller exits to the Suspend state when starting to generate the SOF over the

USB line.

<Any

other

State>

Host

Ready

Host

Idle

UHCR.SOFEN=1

UHCR.SOFEN=0

Device

Connection

Clock stopped

Macro off

Device

Disconnection

Device

Disconnection

Host

Suspend

AT90SCR100 Datasheet(PDF) 209 Page - ATMEL Corporation