char system_clocks_init(void)
{
/******************************************************************
* System Clock 32MHz (XOSC Quarz 16MHz, PLL Faktor 2)
******************************************************************/
/* Nach dem Reset ist die Quelle des Systemtaktes der interne
2MHz RC-Oszillator (System Clock Selection: RC2MHz)
*/
// Oszillator XOSC konfigurieren (12..16MHz, 256 clocks startup time)
CLKSYS_XOSC_Config( OSC_FRQRANGE_12TO16_gc,
false,
OSC_XOSCSEL_XTAL_256CLK_gc );
// Oszillator XOSC enable
CLKSYS_Enable( OSC_XOSCEN_bm );
// Warten bis der Oszillator bereit ist
do {} while ( CLKSYS_IsReady( OSC_XOSCRDY_bm ) == 0 );
// PLL source ist XOSC, Multiplikator x2
CLKSYS_PLL_Config( OSC_PLLSRC_XOSC_gc, 2 );
// Enable PLL
CLKSYS_Enable( OSC_PLLEN_bm );
// Prescalers konfigurieren
CLKSYS_Prescalers_Config(CLK_PSADIV_1_gc, CLK_PSBCDIV_1_1_gc );
// Warten bis PLL locked
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
// Main Clock Source ist Ausgang von PLL
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
// Nun ist der System Clock 32MHz !
/* Hinweis:
32kHz TOSC kann nicht in Verbindung mit PLL genutzt werden, da
die minimale Eingangsfrequenz des PLLs 400kHz beträgt.
*/
return(1);
} // Sets System Clock to 32MHz
void configClock (void) {
// enable 32mhz oscillator
CLKSYS_Enable( OSC_RC32MEN_bm );
do {} while ( CLKSYS_IsReady( OSC_RC32MRDY_bm ) == 0 );
// configure pll source = 32mhz oscillator/4 * 16 = 4*32mhz = 128mhz output
CLKSYS_PLL_Config( OSC_PLLSRC_RC32M_gc, 16 );
// enable pll
CLKSYS_Enable( OSC_PLLEN_bm );
do {} while ( CLKSYS_IsReady( OSC_PLLEN_bm ) == 0 );
// enable prescale by 2 and 2 again to generate 2x and 4x clocks
CCP = CCP_IOREG_gc;
CLK.PSCTRL = CLK_PSBCDIV_2_2_gc;
// select main clock source as pll output
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
}
/*! \brief This function enables the internal 32MHz oscillator and the
* prescalers needed by the HiRes extension.
*
* \note The optimization of the compiler must be set above low to ensure
* that the setting of the CLK register is set within 4 clock cylcles
* after the CCP register is set.
*/
void ConfigClockSystem( void )
{
/* Enable internal 32 MHz ring oscillator and wait until it's
* stable.
*/
CLKSYS_Enable( OSC_RC32MEN_bm );
do {} while ( CLKSYS_IsReady( OSC_RC32MRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_RC32M_gc );
/* Configure PLL with the 32 MHz ring oscillator/4 as source and
* multiply by 16 to get 128 MHz PLL clock and enable it. Wait
* for it to be stable and set prescalers B and C to divide by four
* to set the CPU clock to 32 MHz.
*/
CLKSYS_PLL_Config( OSC_PLLSRC_RC32M_gc, 16 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_2_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
}
void InitClock ()
{
/* Clock Setup */
/* Enable for external 2-9 MHz crystal with quick startup time
* (256CLK). Check if it's stable and set it as the PLL input.
*/
CLKSYS_XOSC_Config( OSC_FRQRANGE_2TO9_gc, false, OSC_XOSCSEL_EXTCLK_gc );
CLKSYS_Enable( OSC_XOSCEN_bm );
do {} while ( CLKSYS_IsReady( OSC_XOSCRDY_bm ) == 0 );
/* Configure PLL with the 8 MHz external clock as source and
* multiply by 4 to get 32 MHz PLL clock and enable it. Wait
* for it to be stable and set prescaler C to divide by two
* to set the CPU clock to 16 MHz.
*/
CLKSYS_PLL_Config(OSC_PLLSRC_XOSC_gc, 4 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_1_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
}
int main(void)
{
// Configure switches
PORTCFG.MPCMASK = 0xFF; // Configure several PINxCTRL registers at the same time
SWITCHPORTL.PIN0CTRL = (SWITCHPORTL.PIN0CTRL & ~PORT_OPC_gm) | PORT_OPC_PULLUP_gc; //Enable pull-up to get a defined level on the switches
SWITCHPORTL.DIRCLR = 0xFF; // Set port as input
// Configure LEDs
PORTCFG.MPCMASK = 0xFF; // Configure several PINxCTRL registers at the same time
LEDPORT.PIN0CTRL = PORT_INVEN_bm; // Invert input to turn STK600 leds on when port value is 1
LEDPORT.DIRSET = 0xFF; // Set port as output
LEDPORT.OUT = 0xA0; // Set initial value
unsigned int counter = 0;
while (1)
{
/* Change the clock source to the internal 2MHz. Disable PLL.
* Configure PLL with the 2 MHz RC oscillator as source and
* multiply by 15 to get 30 MHz PLL clock and enable it. Wait
* for it to be stable and set prescaler C to divide by two
* to set the CPU clock to 15 MHz
*/
if ( (SWITCHPORTL.IN & PIN0_bm) == 0 )
{
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_RC2M_gc );
CLKSYS_Disable( OSC_PLLEN_bm );
CLKSYS_PLL_Config( OSC_PLLSRC_RC2M_gc, 15 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_1_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
LEDPORT.OUTCLR = 0x1F;
LEDPORT.OUTSET = PIN0_bm;
}
/* Configure PLL with the 2 MHz RC oscillator as source and
* multiply by 15 to get 30 MHz PLL clock and enable it. Wait
* for it to be stable and set prescaler B and C to divide by two
* to set the CPU clock to 7.5 MHz
*/
if ( (SWITCHPORTL.IN & PIN1_bm) == 0 )
{
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_RC2M_gc );
CLKSYS_Disable( OSC_PLLEN_bm );
CLKSYS_PLL_Config( OSC_PLLSRC_RC2M_gc, 15 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_2_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
LEDPORT.OUTCLR = 0x1F;
LEDPORT.OUTSET = PIN1_bm;
}
/* Configure PLL with the 2 MHz RC oscillator as source and
* multiply by 6 to get 12 MHz PLL clock and enable it. Wait
* for it to be stable and set prescaler B and C to divide by two
* to set the CPU clock to 3 MHz
*/
if ( (SWITCHPORTL.IN & PIN2_bm) == 0 )
{
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_RC2M_gc );
CLKSYS_Disable( OSC_PLLEN_bm );
CLKSYS_PLL_Config( OSC_PLLSRC_RC2M_gc, 6 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_2_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
LEDPORT.OUTCLR = 0x1F;
LEDPORT.OUTSET = PIN2_bm;
}
/* Dynamically change prescaler:
* Set prescaler A to divide by 2, prescaler B with no division,
* and prescaler C to divide by 2. This will give the CPU a freqency
* of 1/4th of the input freqency. Input freqency will depend on the
* previous switch that has been pressed.
*/
if ( (SWITCHPORTL.IN & PIN3_bm) == 0 )
{
CLKSYS_Prescalers_Config( CLK_PSADIV_2_gc, CLK_PSBCDIV_1_2_gc );
LEDPORT.OUTSET = PIN3_bm;
}
/*
* Add code here for generating 62 MHz to clkper4 and 15.5 MHz to the CPU
*/
if ( (SWITCHPORTL.IN & PIN4_bm) == 0 )
{
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_RC2M_gc );
CLKSYS_Disable( OSC_PLLEN_bm );
CLKSYS_PLL_Config( OSC_PLLSRC_RC2M_gc, 31 );
CLKSYS_Enable( OSC_PLLEN_bm );
CLKSYS_Prescalers_Config( CLK_PSADIV_1_gc, CLK_PSBCDIV_2_2_gc );
do {} while ( CLKSYS_IsReady( OSC_PLLRDY_bm ) == 0 );
CLKSYS_Main_ClockSource_Select( CLK_SCLKSEL_PLL_gc );
LEDPORT.OUTCLR = 0x1F;
LEDPORT.OUTSET = PIN4_bm;
}
// Blink LEDS after the loop has been run several times
// This gives us visual feedback on the MCU speed
counter++;
if (counter > 20000 )
{
LEDPORT.OUTTGL = 0xE0;
counter=0;
}
}
}
