HW Conditions to enter USB DFU state

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A colleague and I are designing a mixed signal board using the AT32UC3C2256. We've decided that we want to primarily use the USB DFU bootloader to program the board. The only thing is, we can't find any information about the hardware conditions used to enter the bootloader. The USB DFU bootloader manual says "The ISP will be activated when the PB0 button on the UC3C-EK kit is pressed at reset," but I can't find any schematics for this board. Is the "PB0" button just connected to the PB00 package pin? Is this the same for all UC3 devices? If anyone has firsthand experience designing a system which uses this functionality, I could use some guidance. Thank you in advance for your help!

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I haven't used the DFU bootloader, but in the FLASHC section there is a section "Bootloader Configuration".

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yxziq1 wrote:
The USB DFU bootloader manual says "The ISP will be activated when the PB0 button on the UC3C-EK kit is pressed at reset," ...
or by ISP_FORCE bit and a watchdog reset.

AVR UC3 USB DFU Boot Loader, Version 1.1.0 and Higher

http://ww1.microchip.com/downloads/en/AppNotes/doc32166.pdf

(page 12)

7.2 Activating the ISP

Note: page 8 for ISP_IO_COND_PIN :

The GPIO pin number to test during the boot process to know whehterto start the USB DFU ISP or the application. 

...

[UC3C (64, 100, 144 pins)]

...

via

Microchip Technology Inc

Microchip Technology

Application Notes

AN_32166 AVR32806: AVR UC3 USB DFU Boot Loader, Version 1.1.0 and Higher

http://www.microchip.com//wwwAppNotes/AppNotes.aspx?appnote=en591315

via https://www.microchip.com/wwwproducts/en/AT32UC3C2256C

 

"Dare to be naïve." - Buckminster Fuller

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Thanks for that document,
I had an old version that didn't include the UC3C and the newer bootloader.

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Hey gchapman, thank you for your response!

 

Looking at the document you pointed me to, I think I may have found my answer. AN32166, page 8: "The default value of the boot loader flash user page Configuration Word2 is (...) 929E7504h for the AVR UC3 C2 series." This means the default value of ISP_IO_COND_PIN is 75h, or GPIO 117, which points to pin 88 (PD21) on the TQFP-100 package for my device. Does this logic seem sound? Thank you again for your response and specific document citations.

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Yes but I'm not a UC3 operator.

The only quick way to test is on STK600 due to EOL of UC3C EK.

 

"Dare to be naïve." - Buckminster Fuller