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femtoduino / femto-usb

FemtoUSB - ATMEL ARM Cortex M0+ (SAMD21), 256KB @ 48MHz, 3V3
MIT License
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crystall less operation? #2

Closed bobricius closed 9 years ago

bobricius commented 9 years ago

hi, I am arm newbie but I read somewhere that atsamd21 have crystall less usb operation, do you anybody tested any bootloader work without crystal?

zrecore commented 9 years ago

According to the docs, it has internal clocks for this...but I've also read about issues (USB won't work?)

...I'll give it a go and see what happens

bobricius commented 9 years ago

for compatbility with arduino zero I have plan add 32khz crystall.

zrecore commented 9 years ago

The SAM D21 should operate with a 48MHz crystal. I wouldn't recommend a crystal-less operation unless USB isn't a big deal.