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adafruit / uf2-samdx1

MSC bootloader (based on UF2) for SAMD21
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Changes needed for SAMD21E15 #65

Closed timmit99 closed 5 years ago

timmit99 commented 5 years ago

What would need to be done to make a version of this bootloader that works on a SAMD21E15? I have 2 chips on breakouts, both a SAMD21E15 and a ATSAMD21E18 the Trinket M0 bootloader works fine on the E18 but not on the E15.

I'm not sure what would have to be done to make this work. The only difference between the two chips is the capacities of the two:

I am not much of a programmer but i can take some guidance and see if i can make it work but i do not know where to start.

dhalbert commented 5 years ago

4kB of RAM is not much. The bootloader code probably assumes a much larger available amount. The stack alone might use that up.

The bootloader also normally uses up 8kB of flash (program memory), which is a significant chunk of 32kB.

What is your application for this small chip? How does using the UF2 bootloader help this application, as opposed to using, say, the SAM-BA bootloader, or using no bootloader at all?

timmit99 commented 5 years ago

I am working on a work project and i have a bunch of the E15's from another retired work project. I was hoping to get this bootable so i can program it in arduino IDE/Atmel Studio over USB without having to be near the board to press the bootloader button/switch. The code itself is very lightweight ( 10kB) so having a smaller/cheeper chip in here would be best and not having to rebuy chips is preferable I dont know what would be entailed but if i could disable the USB mass storage feature that would hopefully decrease the program size. At that point i really dont know what other options are out there for bootloaders.

dhalbert commented 5 years ago

If you just want Arduino compatibility, you can make an Arduino bootloader using the sources here: https://github.com/arduino/ArduinoCore-samd/tree/master/bootloaders/zero. That will probably be easier, though I don't know if it would run on such a small RAM chip. But consider whether it is really worth it, given your time and the cost of new chips/boards.

ladyada commented 5 years ago

hiya gonna close this because its probably not going to work on the '15 and we have no plans to support that chip. please try the bossa bootloader above, it may work? or you may have to buy new chips