Is necessary burn bootloader on AT91SAM3X8E?

[OSCARRAMIREZ]

Hi! We are thinking to use AT91SAM3X8E, before we were using ATMEGA328P, as you know, on 328P is necessary burn bootloader when you buy the micro for to can upload a sketch. Is necessary in case of AT91SAM3X8E the same process? i saw in other forums that is not necessary because is burned in factory.

Can you validate that info?

Thanks a lot, waiting your answer.

[westfw]

The Arduino "Burn Bootloader" command usually does two things:

1. Sets the chip configuration ("Fuses", on an AVR) appropriately for working with the Arduino environment. This includes the fuses that say whether a bootloader is present, and how big it is, but it also includes other details, like memory protection and clock configuration.
2. Loads the bootlloader into the appropriate spot in flash memory.

Now, the SAM3X8E has a bootloader in ROM, so there is no need for the 2nd function (and consequently, I don't believe that the "burn bootloader" would actually load any code.)
The SAM3 DOES have a few "configuration" bits (GPNVM) that you'll need to make sure are set correctly for your application. I think that the default settings are correct for an Arduino, but ...

(incidentally, the Arduino IDE doesn't seem to support any "programmers" for the SAM3 platforms, so the "burn bootloader" operation doesn't work. If you need to make changes, you'd have to do it either programmatically or with a JTAG/SWD programmer.)

[OSCARRAMIREZ]

Hi westfw, thanks for your answer.

Sorry but your answer is not clear for me yet. We want to buy the chip and directly to solde and upload the sketch (with ftdi, usb-uart, etc..). Is this possible? Have we to do any process before upload the sketch?

Thanks for your time.

[westfw]

You have to provide the mechanism(s) for activating the bootloader that is in ROM. I think that means implementing the "erase" signal because the bootloader will run if flash is erased, but I'm not familiar with the details.

9.1.4

Boot Strategies

The system always boots at address 0x0. To ensure maximum boot possibilities, the memory layout can be changed via GPNVM.

A general-purpose NVM (GPNVM1) bit is used to boot either on the ROM (default) or from the Flash.

The GPNVM bit can be cleared or set respectively through the "Clear General-purpose NVM Bit" and "Set General-purpose NVM Bit" commands of the EEFC User Interface.

Setting GPNVM Bit 1 selects the boot from the Flash, clearing it selects the boot from the ROM. Asserting ERASE clears GPNVM Bit 1 and thus selects the boot from the ROM by default.

GPNVM2 enables to select if Flash 0 or Flash 1 is used for the boot.
Setting GPNVM bit 2 selects the boot from Flash 1, clearing it selects the boot from Flash 0.