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1  Products / Arduino Due / Watchdog timer on: November 18, 2012, 05:38:00 am

I think it's not possible to use Watchdog timer on Arduino Duo (with Arduino framework), regarding data sheet (17.4, p.268):

"The Watchdog Mode Register (WDT_MR) can be written only once. Only a processor reset
resets it. Writing the WDT_MR register reloads the timer with the newly programmed mode

and watchdog is disabled at startup in init() function:

"// Disable watchdog

This makes it impossible to turn it again. It would be nice to have possibility to turn it on, for now it's some limitation here.

2  Products / Arduino Due / Re: Arduino Due Initialization on: November 17, 2012, 05:56:44 am
Many thanks for replay.

It looks like 'hardware/arduino/sam/cores/arduino' is an Arduino part with the entry point main.cpp. Then, I think initialization of MCU is done in init() function from 'hardware/arduino/sam/variants/arduino_due_x/variant.cpp'.

The init() uses SystemInit() function, it's probably from 'hardware/arduino/sam/system/CMSIS/Device/ATMEL/sam3xa/source/system_sam3xa.c'.

It seems that this CMSIS folder contains some standard libraries provided by ARM:

'hardware/arduino/sam/system/libsam/' is also interesting, it contains functions to use some pheripherals, like RTC, SPI or Watchdog.

3  Products / Arduino Due / Arduino Due Initialization on: November 16, 2012, 03:39:32 pm

I'm new to Arduino and I'm little bit confused about start up initialization. Is there any information on how DUE is initializated? Especially I'm wondering if it starts at 84MHz or I have to set up PLL myself?

I think arduino_due_x/variant.cpp is file where some initialization is done, but then it use SystemInit(), but I'm not able to find this function quickly.

Thanks for any suggestion.

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