嵌入式学习——硬件（s3c2440外部中断、定时器中断）—

嵌入式学习——硬件（s3c2440外部中断、定时器中断）——day54

1. start.s

	preserve8area reset, code, readonlycode32entryldr pc, =startnopnopnopnopnop						   ldr pc, =interrupt_handlernopstartldr sp, =0x40001000mrs r0, cpsrbic r0, r0, #0x1Forr r0, r0, #0x12;IRQbic r0, r0, #(1 << 7);打开IRQ中断允许msr cpsr_c, r0ldr sp, =0x40001000sub sp, sp, #1024mrs r0, cpsrbic r0, r0, #0x1Forr r0, r0, #0x10 ;Usermsr	cpsr_c, r0ldr sp, =0x40001000sub sp, sp, #2048import mainb maininterrupt_handlersub lr, lr, #4	stmfd sp!, {r0-r12, lr}import do_interruptbl do_interruptldmfd sp!, {r0-r12, pc}^finishedb finishedend

2. main.c——timer4是一个纯粹的定时器

#include <s3c2440.h>
#include "led.h"
#include "key.h"
#include "interrupt.h"void init_wdt(void)	//初始化看门狗，禁止启动,关闭看门狗
{WTCON &= ~(1 << 0);
}void delay(unsigned int n)
{while (n--);
}void init_clk(void)
{unsigned int t = MPLLCON; //将PCLK频率存入变量设置好再进行修改，防止频率修改中途器件因为频率过高而短路t &= ~((0xff << 12) | (0x3f << 4) | (3 << 0)); //利用锁相环将12MHz倍频t |= ((127 << 12) | (2 << 4) | (1 << 0)); //配置fclk频率大约为400MhzCLKDIVN |= ((2 << 1) | (1 << 0));//分频，配置HCLK为100MHz，HCLK为50MHz	MPLLCON = t;//将所有频率配置好再进行设置，防止器件被烧坏
}void timer4_handler(void)
{static unsigned int n = 0;++n;	  if (n > 1000)  //定时器中断触发次数次数{ledAllNor();n = 0;}
}void init_timer4(void)
{TCFG0 |= (24 << 8);	//配置定时器 4 预分频值25  50/25=2MHzTCFG1 &= ~(0x0f << 16);// 选择 PWM 定时器 4 的选通输入1/2 2/2=1MHzTCNTB4 = 1000;//设置定时器 4 的计数缓冲器的值为1000 ，1000减到0触发一次定时器中断	TCON |= (1 << 22); //自动重载TCON |= (1 << 21); // 定时器 4 的手动更新TCON &= ~(1 << 21);// 定时器 4 的手动更新复位INTMOD &= ~(1 << IRQ_INT_TIMER4);//配置定时器4中断为IRQ模式INTMSK &= ~(1 << IRQ_INT_TIMER4);//让定时器中断处于可服务模式TCON |= (1 << 20);//启动定时器4register_irq(IRQ_INT_TIMER4, timer4_handler);//注册定时器中断处理函数				 
}int main(void)
{init_wdt();init_led();init_key();init_clk();init_timer4();while (1){
//		ledAllNor();
//		delay(0xffff);}
}

3. led.h

#ifndef _LED_H_
#define _LED_H_extern void init_led(void);
extern void ledon(unsigned int n);
extern void ledAllOn(void);
extern void ledAllOff(void);
extern void ledAllNor(void);
extern void ledoff(unsigned int n);#endif

4. led.c

#include <s3c2440.h>
#include "led.h"
#include "key.h"
#include "interrupt.h"void init_led(void)	//初始化led	，输出模式
{GPBCON &= ~((3 << 10) | (3 << 12) | (3 << 14) | (3 << 16));GPBCON |= ((1 << 10) | (1 << 12) | (1 << 14) | (1 << 16));ledAllOff();		
}void ledon(unsigned int n)
{if (n < 1 || n > 4){return;}GPBDAT &= ~(1 << (n + 4));
}void ledAllOn(void)
{GPBDAT &= ~(0x0f << 5);	
}void ledAllOff(void)
{GPBDAT |= (0x0f << 5);	
}void ledAllNor(void)
{GPBDAT ^= (0x0f << 5);
}void ledoff(unsigned int n)
{if (n < 1 || n > 4){return;}GPBDAT |= (1 << (n + 4));
}

5. key.h

#ifndef _KEY_H_
#define _KEY_H_extern void init_key(void);
extern void key_handler(void);#endif

6. key.c

#include <s3c2440.h>
#include "led.h"
#include "key.h"
#include "interrupt.h"void init_key(void)	//按键中断EINT 8 11 13 14 15 19
{INTMOD &= ~(1 << IRQ_EINT8_23);//EINT8_23设置为IRQ		中断模式 （INTMOD ） 寄存器INTMSK &= ~(1 << IRQ_EINT8_23);//EINT8_23设置为可服务 中断屏蔽 （INTMSK ） 寄存器GPGCON &= ~((3 << 0) | (3 << 6) | (3 << 10) | (3 << 12) | (3 << 14) | (3 << 22));GPGCON |= ((1 << 1) | (1 << 7) | (1 << 11) | (1 << 13) | (1 << 15) | (1 << 23));//按键改为触发外部中断模式GPGUP |= ((1 << 0) | (1 << 11));//禁止附加上拉电阻EXTINT1 |= ((2 << 0) | (2 << 12) | (2 << 20) | (2 << 28)); //为外部中断配置信号触发方式EXTINT1 |= ((1 << 3) | (1 << 15) | (1 << 23) | (1 << 27) | ((unsigned int)1 << 31));//下降沿触发+信号滤波		EXTINT2 |= ((2 << 12) | (1 << 15));EINTMASK &= ~((1 << 8) | (1 << 11) | (1 << 13) | (1 << 14) | (1 << 15) | (1 << 19));	register_irq(IRQ_EINT8_23, key_handler);//注册由enit8_23导致产生的中断函数
}void key_handler(void)
{if (EINTPEND & (1 << 8))//判断具体是哪个子中断源引发中断{ledAllNor();}else if (EINTPEND & (1 << 11)){ledAllNor();	}else if (EINTPEND & (1 << 13)){ledon(1);	}else if (EINTPEND & (1 << 14)){ledon(2);	}else if (EINTPEND & (1 << 15)){ledon(3);	}else if (EINTPEND & (1 << 19)){ledon(4);	}EINTPEND = EINTPEND;
}

7. interrupt.h

#ifndef _INTERRUPT_H_
#define _INTERRUPT_H_typedef void (*irq_handler)(void);
#define IRQ_EINT8_23 5
#define IRQ_INT_TIMER4 14extern void do_interrupt(void);
extern void register_irq(int irq_num, irq_handler handler);#endif

8. interrupt.c

#include <s3c2440.h>
#include "led.h"
#include "key.h"
#include "interrupt.h"static irq_handler handler_vector[60];//static防止别人去修改，只能在本interrupt.c文件中使用void do_interrupt(void)
{int n = INTOFFSET;handler_vector[n]();SRCPND = SRCPND;//先清srcINTPND = INTPND;//置位																							  
}void register_irq(int irq_num, irq_handler handler)
{handler_vector[irq_num]	= handler;
}

1. 中断执行流程

1. 中断源发出中断请求

2. CPU查询中断是否被运行、以及中断是否被屏蔽

3. CPU考察中断优先级

4. CPU保护现场

5. 执行中断服务函数

6. 恢复现场

2. 外部中断是带有sub寄存器的子请求源

3. 对pend寄存器写1是清零