I am using an Arduino Due as a prototyping board for a microcontroller project. The due has the chip Atmel ATSAM3X8E, with an ARM Cortex-M3 core. I am programming the flash directly using Atmel Studio and SAM-BA over USB, I am not using the arduino tools or bootloader in any way, at least not to my knowledge. I am powering it over the USB port on the arduino.

I am able to program the flash and select flash for boot, but the problem is that the chip never works the first time I plug in the power. But if I cut the power and try again, it boots normally and the program starts. Then if I cut the power and wait a while, I have to power it up another two times before it works. It's like there is some volatile charge or RAM in there that needs to have been powered within the last minute for the chip to boot at power up like it should, but I don't know what. The result is the same if I plug the USB into my computer, or from a phone charger. Also the same whether I use the native or arduino programming USB port to power it.

  • How about if you press the reset button? after powering it up for the first time?
    – ammar.cma
    Commented Jan 24, 2016 at 11:14
  • Then it starts correctly
    – GrixM
    Commented Jan 24, 2016 at 15:17
  • Floating bootloader pin?
    – Turbo J
    Commented Jan 24, 2016 at 15:41
  • I don't know if there is a bootloader pin.. Can't find anything about that in the datasheet. Here is the schematic for the arduino: arduino.cc/en/uploads/Main/arduino-Due-schematic.pdf
    – GrixM
    Commented Jan 24, 2016 at 18:08
  • Edit: Maybe the SHDN pin? I see it is related to some kind of sleep / power save mode, and it is not connected
    – GrixM
    Commented Jan 24, 2016 at 18:18


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