AT90SCR100 datasheet(157/433 Pages) ATMEL

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AT90SCR100

14. USB Device Interface

This section contains an overview of the USB module and the description of the registers design

to interface this USB module. It also details the USB interrupt, the Suspend and Resume modes,

the double buffering, the mode detection and the attachment procedure. This section assumes

the reader of this document is comfortable with the USB Specifications V2.0, available on the

www.usb.org

website. He may also refer to the USB register summary, located at the end of this

document to have a complete overview of the registers available. See “Register Summary” on

page 417.

14.1

Features

• USB 2.0 FullSpeed compliant

• Data transfer rates up to 12Mbit/s

• 8 Programmable Endpoints bi-directionnals

– Endpoint 0 for control: 64bytes

– Endpoints 1 to 3 support double buffers of 64bytes each

– Endpoints 4 to 7: 8 bytes each

• Suspend/Resume Interrupts

• Resume Wake Up Capabilities

• Automatic NACK if USB not ready to transmit/receive

• Specific USBDMA connected for fast and easy copy from Endpoint to RAM

14.2

Overview

The following diagram represents the USB module that contains the necessary logic to commu-

nicate via a Full-Speed USB port.

In Register configuration, you may see ‘X’ suffix at the end of some register. This

value is to be changed into 0, 1, 2, 3, 4, 5, 6 and 7 according to the endpoint

targeted.

The USBENUM is designed to target choose the endpoint to target.

Note

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