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7618C–AVR–07/08

Figure 4-1.

Example of Firmware Download Zero Length DFU_DNLOAD Request

The Host sends a DFU_DNLOAD request with Zero Length Packet (ZLP) to indicate that it has

completed transferring the firmware image file. This is the final payload packet of a download

operation.

4.6.1.4

Answers from Bootloader

After each program request, the Host can request the device state and status by sending a

DFU_GETSTATUS message.

If the device status indicates an error, the host must send a DFU_CLRSTATUS request to the

device.

4.7

Reading the Flash or EEPROM Data

The flow described below allows the user to read data in the Flash memory or in the EEPROM

data memory. A blank check command on the Flash memory is possible with this flow.

This operation is performed in 2 steps:

• DFU_DNLOAD request with the read command (6 bytes)

• DFU_UPLOAD request which correspond to the previous command.

OUT

Prog_Start + (EP0 fifo length - 6) x 00h

SETUP

DFU_DNLOAD

OUT

X offset bytes + Firmware Packet 1

OUT

Firmware Packet 2

OUT

Firmware Packet n + DFU suffix

IN

ZLP