AVR Freaks

I can't see a problem using the ASF functions to set the clock - they only work on an AVR. You wouldn't port those functions to another cpu.

Setting the Xmega clock really doesn't require using a library if you just read the manuals and set a few bits.

Two examples, (in Basic), below, but they show the concept.

It should be easy to port it to C.

In one example the Xmega runs at 32 MHz from the internal 32 MHz Osc.

This routines polls the 32 MHz Osc status to see when it is powered up and stable, and it is OK to switch to it.

In the other example the Xmega runs at 32 MHz from an external 16 MHz Xtal, and by setting the PLL to x2.

This one doesn't bother reading the status bit for the clock of interest, it just delays a mSec and assumes that the Osc is good to go.

I know the real programmers hate code with numbers setting the bits.

Oh well.

The numbers are in decimal.

The comments describe what is taking place.

Don't forget the Configuration Change Register instructions when making changes to the clock.

JC

Clockopt5:
   'Set up the Xmega Clock. Works.
   'Run at 32 MHz from the Internal 32 MHz Osc, set by my code.
   'Xmega runs on Int 2MHz Osc on Startup.
   'This turns on the Int 32 MHz Osc, awaits it being ready, and switches to it.
   'Don't forget the Configuration Change Register Protection Trigger before
   'changing the uC's Clock Source.
   'First turn ON the 32 MHz Int Osc:
   'Then wait until the Int 32 MHz Osc is ready to be used.

   Osc_ctrl = 2                                             'Int 32 MHz Osc ON
   Rvbit = 0                                                'Clear flag
   While Rvbit = 0
      'Read the Int 32 MHz Osc Status
      Regdata = Osc_status                                  'Status of all Int Osc Sources
      Rvbit = Regdata.1                                     'Int 32 MHz Osc Status, 1 = Ready
   Wend
   Cpu_ccp = 216                                            'Config Change Protection
   Clk_ctrl = 1                                             'Use Int 32 MHz Osc
   Return

Clockopt6:
   'Set up the Xmega clock.  Works.
   'Run on External Xtal, (16 MHz), at 32 MHz, via the PLL x2.
   'This MANUALLY turns on the Xmega PLL.
   'Xmega runs at 2MHz on power up.

   Osc_xoscctrl = 203                                       'Ext Osc: 12-16MHz, 16 K Clks
   Osc_ctrl = 9                                             'PLL Off, Ext Xtal On, Int 2M OSC On
   Clk_psctrl = 0                                           'No PreScaler in use
   Osc_pllctrl = 194                                        'PLL: Ext Xtal 16 MHz, Multi x2
   Waitms 1
   Osc_ctrl = 31                                            'PLL ON, All Osc Sources On
   Waitms 1
   Cpu_ccp = 216                                            'Config Change Protection
   Clk_ctrl = 4                                             'Use PLL as Clock Source
   Return

Edit:  Typo.