www.pudn.com > BasicUSB.rar > Cstartup_SAM7.c

//*---------------------------------------------------------------------------- 
//*         ATMEL Microcontroller Software Support  -  ROUSSET  - 
//*---------------------------------------------------------------------------- 
//* The software is delivered "AS IS" without warranty or condition of any 
//* kind, either express, implied or statutory. This includes without 
//* limitation any warranty or condition with respect to merchantability or 
//* fitness for any particular purpose, or against the infringements of 
//* intellectual property rights of others. 
//*---------------------------------------------------------------------------- 
//* File Name           : Cstartup_SAM7.c 
//* Object              : Low level initializations written in C for Tools 
//* Creation            : 12/Jun/04 
//* 1.2   28/Feb/05 JPP : LIB change AT91C_WDTC_WDDIS & PLL 
//* 1.3   21/Mar/05 JPP : Change PLL Wait time 
//* 1.4   21/Aug/05 JPP : Change MC_FMR Setting 
//* 1.5   29/Aug/05 JPP : Change PLL error 
//*---------------------------------------------------------------------------- 
 
// Include the board file description 
#include "Board.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); 
 
//*---------------------------------------------------------------------------- 
//* \fn    AT91F_LowLevelInit 
//* \brief This function performs very low level HW initialization 
//*        this function can be use a Stack, depending the compilation 
//*        optimization mode 
//*---------------------------------------------------------------------------- 
void AT91F_LowLevelInit( void) 
{ 
 int            i; 
 AT91PS_PMC     pPMC = AT91C_BASE_PMC; 
    //* Set Flash Waite sate 
	//  Single Cycle Access at Up to 30 MHz, or 40 
	    AT91C_BASE_MC->MC_FMR = AT91C_MC_FWS_1FWS ; 
 
    //* Watchdog Disable 
        AT91C_BASE_WDTC->WDTC_WDMR= AT91C_WDTC_WDDIS; 
 
	//* Set MCK at 47 923 200 
    // 1 Enabling the 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 Checking the Main Oscillator Frequency (Optional) 
	// 3 Setting PLL and divider: 
		// - div by 14 Fin = 1.3165 =(18,432 / 14) 
		// - Mul 72+1: Fout =	96.1097 =(3,6864 *73) 
		// for 96 MHz the erroe is 0.11% 
		// 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 & 14 ) | 
                         (AT91C_CKGR_PLLCOUNT & (28<<8)) | 
                         (AT91C_CKGR_MUL & (72<<16))); 
 
 
        // Wait the startup time 
        while(!(pPMC->PMC_SR & AT91C_PMC_LOCK)); 
        while(!(pPMC->PMC_SR & AT91C_PMC_MCKRDY)); 
 	// 4. Selection of Master Clock and Processor Clock 
 	// select the PLL clock divided by 2 
 	    pPMC->PMC_MCKR =  AT91C_PMC_PRES_CLK_2 ; 
 	    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 ; 
 
}