startup.c

Bootloader for Atmel AT91SAM7S128 lloader_sram9 - The ARM code pc2 - The pc software

#include "common.h"
#include "startup.h"

// The following functions must be write in ARM mode this function called directly
// by exception vector
extern void AT91F_Spurious_handler(void);
extern void AT91F_Default_IRQ_handler(void);
extern void AT91F_Default_FIQ_handler(void);

void hwinit( void)
{
	int i;
	AT91PS_PMC pPMC = AT91C_BASE_PMC;
	
	//Flash Waite sate
	//(MCK/1000000+1)
	AT91C_BASE_MC->MC_FMR = ((AT91C_MC_FMCN)&(48<<16)) | AT91C_MC_FWS_1FWS ;

    //Watchdog Disable
	AT91C_BASE_WDTC->WDTC_WDMR= AT91C_WDTC_WDDIS;

    // 1 Enable Main Oscillator:
        // SCK = 1/32768 = 30.51 uSecond
    	// Start up time = 8 * 6 / SCK = 56 * 30.51 = 1,46484375 ms
       pPMC->PMC_MOR = ((( AT91C_CKGR_OSCOUNT & (0x06 <<8)) | AT91C_CKGR_MOSCEN ));
        // Wait the startup time
        while(!(pPMC->PMC_SR & AT91C_PMC_MOSCS));
				
	// 2 Check Main Oscillator Frequency (Optional)
	
	// 3 Set PLL and divider:
		// - div by 5 Fin = 3,6864 =(18,432 / 5)
		// - Mul 25+1: Fout =	95,8464 =(3,6864 *26)
		// for 96 MHz the error is 0.16%
		// Field out NOT USED = 0
		// PLLCOUNT pll startup time estimate at : 0.844 ms
		// PLLCOUNT 28 = 0.000844 /(1/32768)
       pPMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x05) |
                         (AT91C_CKGR_PLLCOUNT & (28<<8)) |
                         (AT91C_CKGR_MUL & (25<<16)));

        // Wait the startup time
        while(!(pPMC->PMC_SR & AT91C_PMC_LOCK));
        while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));
		
		
 	// 4. Select Master Clock and Processor Clock
 	// select the PLL clock divided by 2
 	    pPMC->PMC_MCKR =  AT91C_PMC_PRES_CLK_32 ;
 	    while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));

 	    pPMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK  ;
 	    while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY));
		

	// Set up the default interrupts handler vectors
	AT91C_BASE_AIC->AIC_SVR[0] = (int) AT91F_Default_FIQ_handler ;
	for (i=1;i < 31; i++)
	{
	    AT91C_BASE_AIC->AIC_SVR[i] = (int) AT91F_Default_IRQ_handler ;
	}
	AT91C_BASE_AIC->AIC_SPU  = (int) AT91F_Spurious_handler ;

}