本文开发环境mini2440，完成目标：裸机完成定时器中止使LED0以1秒闪耀。
int.c函数
/** init.c: 进行一些初始化*/#include "s3c24xx.h"void disable_watch_dog(void);void clock_init(void);void memsetup(void);void copy_steppingstone_to_sdram(void);void init_led(void);void timer0_init(void);void init_irq(void);/** 封闭WATCHDOG，不然CPU会不断重启*/void disable_watch_dog(void){WTCON = 0; // 封闭WATCHDOG很简单，往这个寄存器写0即可}#define S3C2410_MPLL_200MHZ ((0x5c<<12)|(0x04<<4)|(0x00))#define S3C2440_MPLL_200MHZ ((0x5c<<12)|(0x01<<4)|(0x02))/** 关于MPLLCON寄存器，[19:12]为MDIV，[9:4]为PDIV，[1:0]为SDIV* 有如下计算公式：* S3C2410: MPLL(FCLK) = (m * Fin)/(p * 2^s)* S3C2410: MPLL(FCLK) = (2 * m * Fin)/(p * 2^s)* 其间: m = MDIV + 8, p = PDIV + 2, s = SDIV* 关于本开发板，Fin = 12MHz* 设置CLKDIVN，令分频比为：FCLK:HCLK:PCLK=1:2:4，* FCLK=200MHz,HCLK=100MHz,PCLK=50MHz*/void clock_init(void){// LOCKTIME = 0x00ffffff; // 运用默认值即可CLKDIVN = 0x03; // FCLK:HCLK:PCLK=1:2:4, HDIVN=1,PDIVN=1/* 假如HDIVN非0，CPU的总线形式应该从“fast bus mode”变为“asynchronous bus mode” */__asm__("mrc p15, 0, r1, c1, c0, 0\n" /* 读出操控寄存器 */"orr r1, r1, #0xc0000000\n" /* 设置为“asynchronous bus mode” */"mcr p15, 0, r1, c1, c0, 0\n" /* 写入操控寄存器 */);/* 判别是S3C2410仍是S3C2440 */if ((GSTATUS1 == 0x32410000) || (GSTATUS1 == 0x32410002)){MPLLCON = S3C2410_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */}else{MPLLCON = S3C2440_MPLL_200MHZ; /* 现在，FCLK=200MHz,HCLK=100MHz,PCLK=50MHz */}}/** 设置存储操控器以运用SDRAM*/void memsetup(void){volatile unsigned long *p = (volatile unsigned long *)MEM_CTL_BASE;/* 这个函数之所以这样赋值，而不是像前面的试验(比方mmu试验)那样将装备值* 写在数组中，是因为要生成”方位无关的代码”，使得这个函数能够在被到* SDRAM之前就能够在steppingstone中运转*//* 存储操控器13个寄存器的值 */p[0] = 0x22011110; //BWSCONp[1] = 0x00000700; //BANKCON0p[2] = 0x00000700; //BANKCON1p[3] = 0x00000700; //BANKCON2p[4] = 0x00000700; //BANKCON3p[5] = 0x00000700; //BANKCON4p[6] = 0x00000700; //BANKCON5p[7] = 0x00018005; //BANKCON6p[8] = 0x00018005; //BANKCON7/* REFRESH,* HCLK=12MHz: 0x008C07A3,* HCLK=100MHz: 0x008C04F4*/p[9] = 0x008C04F4;p[10] = 0x000000B1; //BANKSIZEp[11] = 0x00000030; //MRSRB6p[12] = 0x00000030; //MRSRB7}void copy_steppingstone_to_sdram(void){unsigned int *pdwSrc = (unsigned int *)0;unsigned int *pdwDest = (unsigned int *)0x30000000;while (pdwSrc < (unsigned int *)4096){*pdwDest = *pdwSrc;pdwDest++;pdwSrc++;}}/** LED1,LED2,LED4对应GPB5、GPB6、GPB7、GPB8*/#define GPB5_out (1<<(5*2))#define GPB6_out (1<<(6*2))#define GPB7_out (1<<(7*2))#define GPB8_out (1<<(8*2))#define GPB5_msk (3<<(5*2))#define GPB6_msk (3<<(6*2))#define GPB7_msk (3<<(7*2))#define GPB8_msk (3<<(8*2))void init_led(void){// LED1,LED2,LED3,LED4对应的4根引脚设为输出GPBCON &= ~(GPB5_msk | GPB6_msk | GPB7_msk | GPB8_msk);GPBCON |= GPB5_out | GPB6_out | GPB7_out | GPB8_out;}/** Timer input clock Frequency = PCLK / {prescaler value+1} / {divider value}* {prescaler value} = 0~255* {divider value} = 2, 4, 8, 16* 本试验的Timer0的时钟频率=100MHz/(99+1)/(16)=62500Hz* 设置Timer0 0.5秒钟触发一次中止：*/void timer0_init(void){TCFG0 = 99; // 预分频器0 = 99TCFG1 = 0x03; // 挑选16分频TCNTB0 = 62500; // 0.5秒钟触发一次中止TCON |= (1<<1); // 手动更新TCON = 0x09; // 主动加载，清“手动更新”位，发动定时器0}/** 定时器0中止使能*/void init_irq(void){// 定时器0中止使能INTMSK &= (~(1<<10));}
中止函数interrupt.c
#include "s3c24xx.h"void Timer0_Handle(void){/** 每次中止令4个LED改动状况,亮灭替换*/if(INTOFFSET == 10){GPBDAT = ~(GPBDAT & (0xf << 5));}//清中止SRCPND = 1 << INTOFFSET;INTPND = INTPND;}
主函数main.c
int main(void){while(1);return 0;}
本程序依据韦东山嵌入式linux使用开发修正，适用于mini2440做定时器中止试验。
