The SAM-BA Boot program seeks to detect a source clock either from the embedded main oscillator with external crystal (main oscillator enabled) or from a 12 MHz signal applied to the XINpin (Main oscillator in bypass mode).If a clock is found from the two possible sources above, the boot program checks to verify thatthe frequency is 12 MHz (taking into account the frequency range of the 32 kHz RC oscillator). Ifthe frequency is 12 MHz, USB activation is allowed, else (no clock or frequency other than12MHz), the internal 12 MHz RC oscillator is used as main clock and USB clock is not alloweddue to frequency drift of the 12 MHz RC oscillator.
I did a design with the SAM3U a while back, and although I never built it I had the same as you for the parts you are showing.Not much help I know but at least somebody else interpreted the data sheet the same so it's likely your circuit is right (or we're both wrong).______Rob
How far did you come in your process, what kinda of problems/solutions did you stumble upon/find?
I can post the schematics it you think that will help, I think I did the same as you but you may spot something.______Rob
I got the same problem here . Using the same "minimal" Circuit.
Here's page 1 of my schematichttp://www.robgray.com/temp/SAM3U-schem.pdfProbably a lot of stuff you aren't interested in and the pin numbers will be different because its the 3U but the pin names are the same.______Rob
Yeah, I saw that document after I built my circuit Ill try to create my circuit like the "3.3V and 1.8V Dual Power Supply Schematic Example" tomorrow and see how it goes. Im planning to replace the old Atmega Chips with this one but, as you already mentioned, the Chip is very critical and stubborn
AND DON"T FORGET the by-passes... much better to have empty places than 'Hangies"... and it took me a lot of "Hangies" before I learned and a lot of 'Magic Blue Smoke" Too. I sincerely wish it didn't smell so bad, though.Bob