at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 53

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

USB Device Port
DFU Protocol
1790A–ATARM–11/03
Figure 17. Xmodem Transfer Example
A 48 MHz USB clock is necessary to use USB Device port. It has been programmed earlier in
the device initialization with PLLB configuration.
The DFU allows upgrade of the firmware of USB devices. The DFU algorithm is a part of the
USB specification. For more details, refer to “USB Device Firmware Upgrade Specification,
Rev. 1.0”.
There are four distinct steps when carrying out a firmware upgrade:
1. Enumeration: The device informs the host of its capabilities.
2. Reconfiguration: The host and the device agree to initiate a firmware upgrade.
3. Transfer: The host transfers the firmware image to the device. Status requests are
4. Manifestation: Once the device reports to the host that it has completed the reprogram-
Figure 18. DFU Protocol
employed to maintain synchronization between the host and the device.
ming operations, the host issues a reset and the device executes the upgraded
firmware.
Host
Host
SOH 02 FD Data[128] CRC CRC
SOH 03 FC Data[100] CRC CRC
SOH 01 FE Data[128] CRC CRC
Prepare to exit DFU mode
Download this firmware
Prepare for an upgrade
DFU mode activated
USB reset
USB reset
ACK
ACK
ACK
EOT
ACK
C
Device
Device
AT91RM3400
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