Hi
i'm working with SAM3 microcontroller with 12MHz external crystal and set the multiplier and divider to have 64MHz for Master Clock then i see mistake when code is running
it's necessary noted that boundary condition for SAM3S is 64MHz for master clock does it have relation to this parameter and should this condition satisfy at all cost
>>and as for VCO, I think you are referring to the internal oscillator. Am I right?
No, I'm talking about a VCO, not an RC oscillator, how do you think PLL's works, magically pulling a higher frequency out of the air? How does a frequency "multiplier" work?
Perhaps you should be discussing the failure of the ATMEL part, with ATMEL? This isn't a Keil issue, go find an FAE.
I'd verify the frequency, and check on any external PLL filter circuits, supplies, and bulk capacitance.
I use an external crystal oscillator with 12 MHZ output. This is the source of my PLL. Ok. I will check the PLL related issues as you said.
But the failure is discussed with Atmel. they've done all sorts of 'I don't exactly understand' tests and answered the parts and our hardware boards were ok and passed all the tests.
So I think the problem should reside in configuration. The problem is really complicated. So I will be glad if you can answer one basic question.
Is configuring a micro-controller at max frequency for master clock wrong? is it discouraged? Or the maximum stated frequency is safe to use at any condition? (considering wait states and other limitations)
Unless there is an errata, then the frequency should be supported for the full temperature range and all other conditions.
The basic exception is that a processor might support a rather wide voltage span. And then there might be multiple maximum frequencies specified in the datasheet depending on which voltage range it is operating in.
But the operating frequency, number of rewrites of the flash memory is basically worst-case guarantees where the devices are expected to have enough safety margins.
Thanks for your help Per