S3C2410 按键控制LED(中断)

一、开发环境

1、硬件平台:UP-TECH2410DVK1.1

2、主机:PC+eclipse

二、相关原理图

S3C2410 按键控制LED(中断)_第1张图片

LED1-->GPC5

LED2-->GPC6

LED3-->GPC7

KEY1-->EINIT3

KEY2-->EINIT5

KEY3-->EINIT9

三、基本原理

通过按键的按下而触发中断,从而进行中断处理,进而实现相应功能(如闪烁LED),然后退出中断。

如何判断按键被按下:

以KEY1为例,未按下时,因为EINT3连接的是VDD,所以为高电平,当按键发生,EINT3连接的是GND,接地,此时为低电平。

S3C2410 按键控制LED(中断)_第2张图片

通过芯片手册可查到EINT3 、5、9连接的为复用管脚,需要先配置对应的GPIOCON,让其为中断引脚。

四、代码部分

1、head.s

@******************************************************************************
@ File:head.S
@ 功能:初始化,设置中断模式、管理模式的栈,设置好中断处理函数
@******************************************************************************       
   
.extern     main
.text 
.global _start 
_start:
@******************************************************************************       
@ 中断向量,本程序中,除Reset和HandleIRQ外,其它异常都没有使用
@******************************************************************************       
    b   Reset

@ 0x04: 未定义指令中止模式的向量地址
HandleUndef:
    b   HandleUndef 
 
@ 0x08: 管理模式的向量地址,通过SWI指令进入此模式
HandleSWI:
    b   HandleSWI

@ 0x0c: 指令预取终止导致的异常的向量地址
HandlePrefetchAbort:
    b   HandlePrefetchAbort

@ 0x10: 数据访问终止导致的异常的向量地址
HandleDataAbort:
    b   HandleDataAbort

@ 0x14: 保留
HandleNotUsed:
    b   HandleNotUsed

@ 0x18: 中断模式的向量地址
    b   HandleIRQ

@ 0x1c: 快中断模式的向量地址
HandleFIQ:
    b   HandleFIQ

Reset:                  
    ldr sp, =4096           @ 设置栈指针,以下都是C函数,调用前需要设好栈
    bl  disable_watch_dog   @ 关闭WATCHDOG,否则CPU会不断重启
    
    msr cpsr_c, #0xd2       @ 进入中断模式
    ldr sp, =3072           @ 设置中断模式栈指针

    msr cpsr_c, #0xd3       @ 进入管理模式
    ldr sp, =4096           @ 设置管理模式栈指针,
                            @ 其实复位之后,CPU就处于管理模式,
                            @ 前面的“ldr sp, =4096”完成同样的功能,此句可省略

    bl  init_led            @ 初始化LED的GPIO管脚
    bl  init_irq            @ 调用中断初始化函数,在init.c中
    msr cpsr_c, #0x5f       @ 设置I-bit=0,开IRQ中断
    
    ldr lr, =halt_loop      @ 设置返回地址
    ldr pc, =main           @ 调用main函数
halt_loop:
    b   halt_loop

HandleIRQ:
    sub lr, lr, #4                  @ 计算返回地址
    stmdb   sp!,    { r0-r12,lr }   @ 保存使用到的寄存器
                                    @ 注意,此时的sp是中断模式的sp
                                    @ 初始值是上面设置的3072
    
    ldr lr, =int_return             @ 设置调用ISR即EINT_Handle函数后的返回地址  
    ldr pc, =EINT_Handle            @ 调用中断服务函数,在interrupt.c中
int_return:
    ldmia   sp!,    { r0-r12,pc }^  @ 中断返回, ^表示将spsr的值复制到cpsr
    
2、init.s

/*
 * init.c: 进行一些初始化
 */ 

#include "s3c24xx.h"

/*
 * LED1,LED2,LED4对应GPF4、GPF5、GPF6
 */
#define	GPF4_out	(1<<(4*2))
#define	GPF5_out	(1<<(5*2))
#define	GPF6_out	(1<<(6*2))

#define	GPF4_msk	(3<<(4*2))
#define	GPF5_msk	(3<<(5*2))
#define	GPF6_msk	(3<<(6*2))

/*
 * S2,S3,S4对应GPF0、GPF2、GPG3
 */
#define GPF0_eint     (0x2<<(0*2))
#define GPF2_eint     (0x2<<(2*2))
#define GPG3_eint     (0x2<<(3*2))

#define GPF0_msk    (3<<(0*2))
#define GPF2_msk    (3<<(2*2))
#define GPG3_msk    (3<<(3*2))

/*
 * 关闭WATCHDOG,否则CPU会不断重启
 */
void disable_watch_dog(void)
{
    WTCON = 0;  // 关闭WATCHDOG很简单,往这个寄存器写0即可
}

void init_led(void)
{
    // LED1,LED2,LED4对应的3根引脚设为输出
    GPFCON &= ~(GPF4_msk | GPF5_msk | GPF6_msk);
    GPFCON |= GPF4_out | GPF5_out | GPF6_out;
}

/*
 * 初始化GPIO引脚为外部中断
 * GPIO引脚用作外部中断时,默认为低电平触发、IRQ方式(不用设置INTMOD)
 */ 
void init_irq( )
{
    // S2,S3对应的2根引脚设为中断引脚 EINT0,ENT2
    GPFCON &= ~(GPF0_msk | GPF2_msk);
    GPFCON |= GPF0_eint | GPF2_eint;

    // S4对应的引脚设为中断引脚EINT11
    GPGCON &= ~GPG3_msk;
    GPGCON |= GPG3_eint;
    
    // 对于EINT11,需要在EINTMASK寄存器中使能它
    EINTMASK &= ~(1<<11);
        
    /*
     * 设定优先级:
     * ARB_SEL0 = 00b, ARB_MODE0 = 0: REQ1 > REQ3,即EINT0 > EINT2
     * 仲裁器1、6无需设置
     * 最终:
     * EINT0 > EINT2 > EINT11即K2 > K3 > K4
     */
    PRIORITY = (PRIORITY & ((~0x01) | (0x3<<7))) | (0x0 << 7) ;

    // EINT0、EINT2、EINT8_23使能
    INTMSK   &= (~(1<<0)) & (~(1<<2)) & (~(1<<5));
}




3、interrupt.c

#include "s3c24xx.h"

void EINT_Handle()
{
    unsigned long oft = INTOFFSET;
    unsigned long val;
    
    switch( oft )
    {
        // S2被按下
        case 0: 
        {   
            GPFDAT |= (0x7<<4);   // 所有LED熄灭
            GPFDAT &= ~(1<<4);      // LED1点亮
            break;
        }
        
        // S3被按下
        case 2:
        {   
            GPFDAT |= (0x7<<4);   // 所有LED熄灭
            GPFDAT &= ~(1<<5);      // LED2点亮
            break;
        }

        // K4被按下
        case 5:
        {   
            GPFDAT |= (0x7<<4);   // 所有LED熄灭
            GPFDAT &= ~(1<<6);      // LED4点亮                
            break;
        }

        default:
            break;
    }

    //清中断
    if( oft == 5 ) 
        EINTPEND = (1<<11);   // EINT8_23合用IRQ5
    SRCPND = 1<

4、main.c

int main()
{
    while(1);
    return 0;
}
5、s3c24xx.h

/* WOTCH DOG register */
#define     WTCON           (*(volatile unsigned long *)0x53000000)

/* SDRAM regisers */
#define     MEM_CTL_BASE    0x48000000
#define     SDRAM_BASE      0x30000000

/* NAND Flash registers */
#define NFCONF              (*(volatile unsigned int  *)0x4e000000)
#define NFCMD               (*(volatile unsigned char *)0x4e000004)
#define NFADDR              (*(volatile unsigned char *)0x4e000008)
#define NFDATA              (*(volatile unsigned char *)0x4e00000c)
#define NFSTAT              (*(volatile unsigned char *)0x4e000010)

/*GPIO registers*/
#define GPBCON              (*(volatile unsigned long *)0x56000010)
#define GPBDAT              (*(volatile unsigned long *)0x56000014)

#define GPFCON              (*(volatile unsigned long *)0x56000050)
#define GPFDAT              (*(volatile unsigned long *)0x56000054)
#define GPFUP               (*(volatile unsigned long *)0x56000058)

#define GPGCON              (*(volatile unsigned long *)0x56000060)
#define GPGDAT              (*(volatile unsigned long *)0x56000064)
#define GPGUP               (*(volatile unsigned long *)0x56000068)

#define GPHCON              (*(volatile unsigned long *)0x56000070)
#define GPHDAT              (*(volatile unsigned long *)0x56000074)
#define GPHUP               (*(volatile unsigned long *)0x56000078)



/*UART registers*/
#define ULCON0              (*(volatile unsigned long *)0x50000000)
#define UCON0               (*(volatile unsigned long *)0x50000004)
#define UFCON0              (*(volatile unsigned long *)0x50000008)
#define UMCON0              (*(volatile unsigned long *)0x5000000c)
#define UTRSTAT0            (*(volatile unsigned long *)0x50000010)
#define UTXH0               (*(volatile unsigned char *)0x50000020)
#define URXH0               (*(volatile unsigned char *)0x50000024)
#define UBRDIV0             (*(volatile unsigned long *)0x50000028)


/*interrupt registes*/
#define SRCPND              (*(volatile unsigned long *)0x4A000000)
#define INTMOD              (*(volatile unsigned long *)0x4A000004)
#define INTMSK              (*(volatile unsigned long *)0x4A000008)
#define PRIORITY            (*(volatile unsigned long *)0x4A00000c)
#define INTPND              (*(volatile unsigned long *)0x4A000010)
#define INTOFFSET           (*(volatile unsigned long *)0x4A000014)
#define SUBSRCPND           (*(volatile unsigned long *)0x4A000018)
#define INTSUBMSK           (*(volatile unsigned long *)0x4A00001c)

/*external interrupt registers*/
#define EINTMASK            (*(volatile unsigned long *)0x560000a4)
#define EINTPEND            (*(volatile unsigned long *)0x560000a8)



6、Makefile

objs := head.o init.o interrupt.o main.o

int.bin: $(objs)
	arm-none-eabi-ld -Ttext 0x00000000 -o int_elf $^
	arm-none-eabi-objcopy -O binary -S int_elf $@
	arm-none-eabi-objdump -D -m arm int_elf > int.dis
	
%.o:%.c
	arm-none-eabi-gcc -Wall -O2 -c -o $@ $<

%.o:%.S
	arm-none-eabi-gcc -Wall -O2 -c -o $@ $<

clean:
	rm -f int.bin int_elf int.dis *.o		
	






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