LUFA Library - DFU Class Bootloader
DFU Class USB AVR Bootloader

Demo Compatibility:

The following list indicates what microcontrollers are compatible with this demo.

USB Information:

The following table gives a rundown of the USB utilization of this demo.

USB Mode: Device
USB Class: Device Firmware Update Class (DFU)
USB Subclass: None
Relevant Standards: USBIF DFU Class Standard, Atmel USB Bootloader Datasheet
Supported USB Speeds: Low Speed Mode
Full Speed Mode

Project Description:

This bootloader enumerates to the host as a DFU Class device, allowing for DFU-compatible programming software to load firmware onto the AVR.

Out of the box this bootloader builds for the AT90USB1287 with an 8KB bootloader section size, and will fit into 4KB of bootloader space. If you wish to alter this size and/or change the AVR model, you will need to edit the MCU, FLASH_SIZE_KB and BOOT_SECTION_SIZE_KB values in the accompanying makefile.

When the bootloader is running, the board's LED(s) will flash at regular intervals to distinguish the bootloader from the normal user application.

Driver Installation

This bootloader is designed to be compatible with Atmel's provided Windows DFU class drivers. You will need to install Atmel's DFU drivers prior to using this bootloader on Windows platforms. If you are using a 64 bit Windows OS, you will need to either disable the driver signing requirement (see online tutorials for details) or use a digitally signed version of the official Atmel driver provided by a third party AVR user at http://www.avrfreaks.net/index.php?module=Freaks%20Academy&func=viewItem&item_id=2196&item_type=project.

Note
This device spoofs Atmel's DFU Bootloader USB VID and PID so that the Atmel DFU bootloader drivers included with FLIP will work. If you do not wish to use Atmel's ID codes, please manually change them in Descriptors.c and alter your driver's INF file accordingly.

Host Controller Application

This bootloader is compatible with Atmel's FLIP utility on Windows machines, and dfu-programmer on Linux machines.

FLIP (Windows)

FLIP (Flexible In-System Programmer) is a utility written by Atmel, and distributed for free on the Atmel website. The FLIP utility is designed to assist in the bootloader programming of a range of Atmel devices, through several popular physical interfaces including USB. It is written in Java, however makes use of native extensions for USB support and thus is only offered on Windows.

To program a device using FLIP, refer to the Atmel FLIP documentation.

dfu-programmer (Linux)

dfu-programmer is an open-source command line solution for the bootloader programming of Atmel devices through a USB connection, using the DFU protocol, available for download at http://sourceforge.net/projects/dfu-programmer/.

The following example loads a HEX file into the AVR's FLASH memory using dfu-programmer:

dfu-programmer at90usb1287 erase flash Mouse.hex

User Application API

Several user application functions for FLASH and other special memory area manipulations are exposed by the bootloader, allowing the user application to call into the bootloader at runtime to read and write FLASH data.

Warning
The APIs exposed by the DFU class bootloader are NOT compatible with the API exposed by the official Atmel DFU bootloader.

By default, the bootloader API jump table is located 32 bytes from the end of the device's FLASH memory, and follows the following layout:

#define BOOTLOADER_API_TABLE_SIZE 32
#define BOOTLOADER_API_TABLE_START ((FLASHEND + 1UL) - BOOTLOADER_API_TABLE_SIZE)
#define BOOTLOADER_API_CALL(Index) (void*)((BOOTLOADER_API_TABLE_START + (Index * 2)) / 2)
void (*BootloaderAPI_ErasePage)(uint32_t Address) = BOOTLOADER_API_CALL(0);
void (*BootloaderAPI_WritePage)(uint32_t Address) = BOOTLOADER_API_CALL(1);
void (*BootloaderAPI_FillWord)(uint32_t Address, uint16_t Word) = BOOTLOADER_API_CALL(2);
uint8_t (*BootloaderAPI_ReadSignature)(uint16_t Address) = BOOTLOADER_API_CALL(3);
uint8_t (*BootloaderAPI_ReadFuse)(uint16_t Address) = BOOTLOADER_API_CALL(4);
uint8_t (*BootloaderAPI_ReadLock)(void) = BOOTLOADER_API_CALL(5);
void (*BootloaderAPI_WriteLock)(uint8_t LockBits) = BOOTLOADER_API_CALL(6);
#define BOOTLOADER_MAGIC_SIGNATURE_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 2))
#define BOOTLOADER_MAGIC_SIGNATURE 0xDCFB
#define BOOTLOADER_CLASS_SIGNATURE_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 4))
#define BOOTLOADER_DFU_SIGNATURE 0xDF10
#define BOOTLOADER_ADDRESS_START (BOOTLOADER_API_TABLE_START + (BOOTLOADER_API_TABLE_SIZE - 8))
#define BOOTLOADER_ADDRESS_LENGTH 4

From the application the API support of the bootloader can be detected by reading the FLASH memory bytes located at address BOOTLOADER_MAGIC_SIGNATURE_START and comparing them to the value BOOTLOADER_MAGIC_SIGNATURE. The class of bootloader can be determined by reading the FLASH memory bytes located at address BOOTLOADER_CLASS_SIGNATURE_START and comparing them to the value BOOTLOADER_DFU_SIGNATURE. The start address of the bootloader can be retrieved by reading the bytes of FLASH memory starting from address BOOTLOADER_ADDRESS_START.

Device Memory Map

The following illustration indicates the final memory map of the device when loaded with the bootloader.

*  +----------------------------+ 0x0000
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |      User Application      |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  |                            |
*  +----------------------------+ FLASHEND - BOOT_AUX_SECTION_SIZE
*  | Booloader Start Trampoline |
*  | (Not User App. Accessible) |
*  +----------------------------+ FLASHEND - (BOOT_AUX_SECTION_SIZE - 4)
*  |                            |
*  |     Auxillery Bootloader   |
*  |  Space for Smaller Devices |
*  | (Not User App. Accessible) |
*  |                            |
*  +----------------------------+ FLASHEND - BOOT_SECTION_SIZE
*  |                            |
*  |   Bootloader Application   |
*  | (Not User App. Accessible) |
*  |                            |
*  +----------------------------+ FLASHEND - 96
*  |   API Table Trampolines    |
*  | (Not User App. Accessible) |
*  +----------------------------+ FLASHEND - 32
*  |    Bootloader API Table    |
*  |   (User App. Accessible)   |
*  +----------------------------+ FLASHEND - 8
*  |   Bootloader ID Constants  |
*  |   (User App. Accessible)   |
*  +----------------------------+ FLASHEND
*

Auxiliary Bootloader Section

To make the bootloader function on smaller devices (those with a physical bootloader section of smaller than 6KB)

Known Issues:

On Linux machines, the DFU bootloader is inaccessible.
On many Linux systems, non-root users do not have automatic access to newly inserted DFU devices. Root privileges or a UDEV rule is required to gain access. See here for resolution steps.
After loading an application, it is not run automatically on startup.
Some USB AVR boards ship with the BOOTRST fuse set, causing the bootloader to run automatically when the device is reset. In most cases, the BOOTRST fuse should be disabled and the HWBE fuse used instead to run the bootloader when needed.

Project Options

The following defines can be found in this demo, which can control the demo behaviour when defined, or changed in value.

Define Name: Location: Description:
SECURE_MODE AppConfig.h If defined to true, the bootloader will not accept any memory commands other than a chip erase on start-up, until an erase has been performed. This can be used in conjunction with the AVR's lockbits to prevent the AVRs firmware from being dumped by unauthorized persons. When false, all memory operations are allowed at any time.