AT90USB128X データシートの表示（PDF） - Atmel Corporation

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AT90USB128X

USB DFU Bootloader Datasheet

Atmel Corporation 

SETUP

IN

OUT

DFU_UPLOAD

Byte value (1 byte)

ZLP

4.9 Erasing the Flash

The flow described below allows the user to erase the Flash memory.

The Full Chip erase command erases the whole Flash.

4.9.1

Request from Host

To start the erasing operation, the Host sends a DFU_DNLOAD request with a Write Command

in the data field (2 bytes).

Command Identifier

Id_write_command

04h

data[0]

00h

data[1]

FFh

data[2]

data[3]

data[4]

Description

Full chip Erase (bits at FFh)

4.9.2

Answers from Bootloader

The device has two possible answers to a DFU_GETSTATUS request:

• If the chip is protected from program access, an “err_WRITE” status is returned to the Host.

• Otherwise, the device status is “OK“.

4.10 Starting the Application

The flow described below allows to start the application directly from the bootloader upon a spe-

cific command reception.

Two options are possible:

• Start the application with an internal hardware reset using watchdog.

When the device receives this command the watchdog is enabled and the bootloader enters

a waiting loop until the watchdog resets the device.

• Start the application without reset.

A jump at the address 0000h is used to start the application without reset.

To start the application, the Host sends a DFU_DNLOAD request with the specified application

start type in the data field (3 or 5 bytes).

This request is immediately followed by a second DFU_DNLOAD request with no data field to

start the application with one of the 2 options.

13

7618C–AVR–07/08

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