Help from the Atmel guys?

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steve17
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Posted by steve17: Thu. Mar 15, 2018 - 07:07 PM
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Is it possible to communicate with the folks that designed the Xmega?  Has Trondheim been obliterated?  Is it now only a blank spot on Google maps, like area 51?

 

The USB silicon seems to do something desirable about disabling DFLL when we are suspended and not receiving SOF.  That works well.  It also tries to enable DFLL when we are resumed and again receiving SOF.  Sometimes this works and sometimes doesn't, with disastrous results to our clock frequency.  None of this appears in the manual, as far as I can see.  I might be able to kludge Atmel's boo boo, but it would be nice to communicate to someone with more knowledge of the silicon.   

 

 

Tags:

AVR Microcontrollers, AVR XMEGA
Last Edited: Thu. Mar 15, 2018 - 07:09 PM
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awneil
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Posted by awneil: Thu. Mar 15, 2018 - 07:47 PM
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You would need to raise a support case through the Microchip site

 

See: https://www.avrfreaks.net/forum/microchipatmel-support-page

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steve17
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Posted by steve17: Thu. Mar 15, 2018 - 09:46 PM
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Thanks, I think I'm in now.  I see my old cases.   For a while, I was thinking it may be easier to switch to another brand of Microcontroller.

 

P.S.  Microchip won't accept special characters in passwords.  I don't know if they will accept zero.  That is a rather new concept to us westerners.

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mojo-chan
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Posted by mojo-chan: Fri. Mar 16, 2018 - 09:48 AM
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Have you looked at the ASF code? It's an onion of many, many layers but when you get to the core it can offer some useful hints on how to handle stuff like DFLL. Just create a dummy USB project and check how it manages DFLL.

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steve17
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Posted by steve17: Fri. Mar 16, 2018 - 07:22 PM
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Just looking at the ASF has got to cause severe brain injury.

 

However if it gets SOF to work as well as I think it should be able to, I may risk my sanity and look at it.

 

If the clock frequency is still good after waking the PC from sleep, while using SOF, I'll take a peek.

 

The real goal is to have SOF fix the frequency after attaching to the USB bus that is way off before attaching to the USB bus. 

 

Can ASF do either of these? 

 

 

Last Edited: Sat. Mar 17, 2018 - 12:41 AM
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mojo-chan
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Posted by mojo-chan: Mon. Mar 19, 2018 - 10:07 AM
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The ASF code does seem to recover when the PC comes out of sleep, yes.

 

You can actually detect when the PC goes to sleep. You are supposed to according to the USB spec, and go into low power state. Basically if you stop getting SOF markers for several milliseconds then you know the PC is napping, and on XMEGA you can use a timer to measure that with the SOF event triggering a timer reset.

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steve17
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Posted by steve17: Sat. Apr 7, 2018 - 04:07 PM
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I did a quick look at the ASF examples.  I'm not sure any of them use SOF to adjust the 32MHz RC osc..   I will investigate some more later.  There is another little project I want to work on now.

 

 

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