Cannot init external 32 kHz crystal on ATxmega256A3BU

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bjornhi
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Location: Sweden
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Posted by bjornhi: Thu. Jun 27, 2013 - 07:46 AM
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Hi fellows,

Previously used a ATxmega128A1 without any problems but the same code does not seem to work on a ATxmega256A3BU:

OSC.XOSCCTRL |= OSC_XOSCSEL1_bm; //Setup startup timer for 32 kHz.
OSC.CTRL |= OSC_XOSCEN_bm;       //External oscillator enabled. 
while ( (OSC.STATUS & OSC_XOSCRDY_bm) == 0); //Waiting for it to become stable

The AVR gets stuck on the last while statement, the xtal never seems to get stable.

Anything obvious I missed? Changed the fuse TOSCSEL to ALTERNATE.

Any ideas are welcome!
/Bjorn

Tags:

AVR Microcontrollers, AVR and XMEGA, ATxmega128A1, ATxmega256A3, ATxmega256A3B, ATxmega256A3BU, ATmega128, ATmega128A
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bjornhi
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Posted by bjornhi: Wed. Aug 14, 2013 - 12:40 PM
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Problem solved!

Module Access Enable bit must be set first:

VBAT.CTRL = VBAT_ACCEN_bm;

Not obvious in the documentation. Hope it helps anyone with the same problem.

Kind regards
Bjorn

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jorge.ar
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Posted by jorge.ar: Wed. Oct 1, 2014 - 06:35 PM
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I have the same problem but don't know where is VBAT defined. When compiling, 'VBAT' undeclared.

 

I'm using atxmega256a3bu.

 

thanks!

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