AT90SCR100 datasheet(212/433 Pages) ATMEL

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TPR0327AY–SMS–30Jan09

AT90SCR100

A clear of UPCRX.PEN will reset the configuration of the Pipe. All the corresponding Pipe regis-

ters are reset to there reset values. Please refer to “Memory Management” section for more

details.

17.5.6

USB Reset

The USB controller sends a USB Reset when the firmware set the UHCR.RESET bit. The

UHINT.RSTI bit is set by hardware when the USB Reset has been sent. This triggers an inter-

rupt if the UHIEN.RSTE has been set.

When a USB Reset has been sent, all the Pipe configuration and the memory allocation are

reset. The General Host interrupt enable register is left unchanged.

If the bus was previously in suspend mode (UHCR.SOFEN = 0), the USB controller automati-

cally switches to the resume mode (UHINT.HWUPI is set) and the UHCR.SOFEN bit is set by

hardware in order to generate SOF immediately after the USB Reset.

17.5.7

Address Setup

Once the Device has answer to the first Host requests with the default address (0), the Host

assigns a new address to the device. The Host controller has to send a USB reset to the device

and perform a SET ADDRESS control request, with the new address to be used by the Device.

This control request ended, the firmware writes the new address into the UHADDR register. All

following requests, on every Pipes, will be performed using this new address.

When the Host controller sends a USB reset, the UHADDR register is reset by hardware and the

following Host requests will be performed using the default address (0).

17.5.8

Remote Wake-Up detection

The Host Controller enters in Suspend mode when clearing the UHCR.SOFEN bit. No more

Start Of Frame is sent on the USB bus and the USB Device enters in Suspend mode 3ms later.

The Device awakes the Host Controller by sending an Upstream Resume (Remote Wake-Up

feature). The Host Controller detects a non-idle state on the USB bus and set the UHINT.HWUPI

bit. If the non-Idle correspond to an Upstream Resume (K state), the UHINT.RXRSMI bit is set

by hardware. The firmware has to generate a downstream resume within 1ms and for at least

20ms by setting the UHCR.RESUME bit.

To initialize the communication with the USB device, the firmware has to configure

the Default Control Pipe with the following parameters:

• Type: Control

• Token: SETUP

• Data Bank:1

• Size: 64 Bytes

The firmware will ask for 8 bytes of the Device Descriptor sending a

GET_DESCRIPTOR request. These bytes contains the MaxPacketSize of the

Device default control endpoint and the firmware will then re-configure the size of

the Default Control Pipe with this size parameter.

Note

AT90SCR100 Datasheet(PDF) 212 Page - ATMEL Corporation

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