Using the AVR32 bootloader - DEPRECATED

Atmel provides a functional bootloader for its UC3 processors. It was intended for reprogramming the firmware after deployment, but it can be also used during development, as a more convenient alternative to JTAG.

How to program the bootloader

The bootloader occupies the first 8 KB of the flash space, and should be programmed using the JTAG.

The Atmel tools to manage chip programming are available in the AVR perspective:

• select the AVR perspective:
  • Eclipse menu: Windows → Open perspective → Other
  • select AVR
  • click the OK button

Erase the chip

Although it seems to be included in the next step, to avoid any surprises, it is recommended to first completely erase the chip before any programming.

Be sure you select Chip Erase…, not just Erase…, to completely erase the chip, including any security bits.

• in the AVR Targets tab, right-click on JTABICE mkII
• click on Chip Erase…
  • read the notificaton message and click the OK button

For reference, on my machine this translated to:

cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --gui --part UC3A3256 chiperase

Program the bootloader code

• in the AVR Targets tab, right-click on JTAGICE mkII
• click on Program Bootloadewr…
  • select the part, the USB DFU type and the latest version (currently 1.0.3)
  • click the Next button
  • in the AT32UC3 Bootloader wizard page
    • set the pin to 42 (or any other value your board supports); this is the pin where the booloader button is connected.
    • deselect the level (the User Page Configuration Word should read 0x929E2A9E)
    • select all 3 bit configurations: ISP_BOD_EN, ISP_IO_COND_EN, ISP_FORCE (the FuseBitConfiguration Value should read 0xFFF7FFFF)
    • click on the Finish button

For reference, on my machine this translated to:

cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 chiperase
cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 program
  -finternal@0x80000000,512Kb -cxtal -e -v -O0x80000000 -Fbin
  C:\Users\LIVIUI~1\AppData\Local\Temp\at32uc3a3-isp-1.0.3.bin9020454716059643611.bin
cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 program
  -finternal@0x80000000,512Kb -cxtal -e -v -O0x808001FC -Fbin
  C:\Users\LIVIUI~1\AppData\Local\Temp\userConf7033399909011047483,dat
cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 writefuses
  -finternal@0x80000000,512Kb gp=0xfff7ffff
cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 reset
cmd.exe /C avr32program -c USB:0700000053E7 -pjtagicemkii --part UC3A3256 run

How to use the bootloader

Configure the USB DFU programmer

Configuring the USB DFU Programmer is certainly possible, but unfortunately it is not obvious, probably due to some bugs.

The first step is to add a new AVR Target. In the properties page, the Details tab, should allow to select the

• Device: AT32UC3A3256 (or some other value to match your board)
• Debugger/programmer: USB DFU
• Clock source: External clock connected to OSC0 (or some other value to match your board)

If these selections are not available, the trick is to play with existing config until they become available. For example you can first configure the JTAGICE mkII first and select the Device.

Program flash image

• in the AVR Targets tab, right-click on USB DFU
  • click the Program… menu item
  • select the file path to the .elf image
  • leave the offset to 0x0
  • set the following options
    • enable Verify memory after programming
    • enable Erase flash before programming
    • enable Unlock flash before erasing
    • disable Reset MCU after programming
    • enable Start executing after programming
  • click the OK button

The device will start to execute the new image as soon as programming is completed.

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