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ARM中的看門狗程序

作者： 時間：2016-11-09 來源：網(wǎng)絡(luò) 收藏
在ARM中，有一個硬件部分叫WATCH DOG。這個硬件，一直在做一件事情：就是，從某一數(shù)值，一直數(shù)，各一段時間減一，隔一段時間減一，直到減到0的時候?qū)|發(fā)重啟或者中斷。而有時候，為了預(yù)防死機，我們在操作系統(tǒng)跑起來的時候會有一個特定的程序來做一件事情：減到特定是值的時候數(shù)值將會重新置到100.這樣，看門狗將會循環(huán)往復(fù)做一件事情：一直數(shù)數(shù)，而不會死機。

這個程序叫做守護程序：又叫做喂狗程序。

本文引用地址：http://butianyuan.cn/article/201611/317866.htm

看門狗的邏輯運算圖如下：

今天，有看門狗來寫了一個程序：隔一段時間來觸發(fā)一個中斷，每次中斷來的時候，將會讓板子上面的燈和蜂鳴器做出相應(yīng)的反映:

首先：在頭文件中將具體的寄存器聲明：

1 2 #define gpiobase        0x113 #define GPM4CON         (*(volatile unsigned long *)(gpiobase + 0x02E0)) 4 #define GPM4DAT         (*(volatile unsigned long *)(gpiobase + 0x02E4))5 #define GPX3CON         (*(volatile unsigned long *)(gpiobase + 0x0C60))6 #define GPX3DAT         (*(volatile unsigned long *)(gpiobase + 0x0C64))7 #define GPD0CON         (*(volatile unsigned long *)(gpiobase + 0x4A0))8 #define GPD0DAT         (*(volatile unsigned long *)(gpiobase + 0x4A4))9 10 #define ICC 0x1048011 12 #define ICCICR_CPU0     (*(volatile unsigned long *)(ICC + 0x0)) 13 #define ICCPMR_CPU0     (*(volatile unsigned long *)(ICC + 0x4)) 14 #define ICCBPR_CPU0     (*(volatile unsigned long *)(ICC + 0x8)) 15 #define ICCIAR_CPU0     (*(volatile unsigned long *)(ICC + 0xC)) 16 #define ICCEOIR_CPU0    (*(volatile unsigned long *)(ICC + 0x0010)) 17 #define ICCRPR_CPU0     (*(volatile unsigned long *)(ICC + 0x0014)) 18 #define ICCHPIR_CPU0    (*(volatile unsigned long *)(ICC + 0x0018)) 19 #define ICCABPR_CPU0    (*(volatile unsigned long *)(ICC + 0x001C)) 20 #define INTEG_EN_C_CPU0 (*(volatile unsigned long *)(ICC + 0x0040)) 21 #define ICCIIDR         (*(volatile unsigned long *)(ICC + 0x00FC))22 23 #define ICD 0x1049024 25 #define ICDDCR            (*(volatile unsigned long *)(ICD + 0x0))26 #define ICDICTR           (*(volatile unsigned long *)(ICD + 0x4))27 #define ICDIIDR           (*(volatile unsigned long *)(ICD + 0x8))28 #define ICDISR0_CPU0      (*(volatile unsigned long *)(ICD + 0x0080))29 #define ICDISER0_CPU0     (*(volatile unsigned long *)(ICD + 0x0100))30 #define ICDISER2_CPU0     (*(volatile unsigned long *)(ICD + 0x0108))31 #define ICDICER0_CPU0     (*(volatile unsigned long *)(ICD + 0x0180))32 #define ICDISPR0_CPU0     (*(volatile unsigned long *)(ICD + 0x0200))33 #define ICDICPR0_CPU0     (*(volatile unsigned long *)(ICD + 0x0280))34 #define ICDABR0_CPU0      (*(volatile unsigned long *)(ICD + 0x0300))35 #define ICDIPR0_CPU0      (*(volatile unsigned long *)(ICD + 0x0400))36 #define ICDIPR1_CPU0      (*(volatile unsigned long *)(ICD + 0x0404))37 #define ICDIPR2_CPU0      (*(volatile unsigned long *)(ICD + 0x0408))38 #define ICDIPR3_CPU0      (*(volatile unsigned long *)(ICD + 0x040C))39 #define ICDIPR4_CPU0      (*(volatile unsigned long *)(ICD + 0x0410))40 #define ICDIPR5_CPU0      (*(volatile unsigned long *)(ICD + 0x0414))41 #define ICDIPR6_CPU0      (*(volatile unsigned long *)(ICD + 0x0418))42 #define ICDIPR7_CPU0      (*(volatile unsigned long *)(ICD + 0x041C))43 #define ICDIPR18_CPU0      (*(volatile unsigned long *)(ICD + 0x448))44 45 #define ICDIPTR0_CPU0   (*(volatile unsigned long *)(ICD + 0x0800))46 #define ICDIPTR1_CPU0   (*(volatile unsigned long *)(ICD + 0x0804))47 #define ICDIPTR18_CPU0  (*(volatile unsigned long *)(ICD + 0x0848))48 #define ICDSGIR     (*(volatile unsigned long *)(ICD + 0x0F00))49 50 51 #define WTCON    (*(volatile unsigned long *)0x10060)52 #define WTDAT    (*(volatile unsigned long *)0x10064)53 #define WTCNT    (*(volatile unsigned long *)0x10068)54 #define WTCLRINT (*(volatile unsigned long *)0x1006C) 55 56 57

在主要的文件中：

1 #include"regs.h"2 3 int (*printf)(char *, ...) = 0xc3e114d8;4 int(*delay)(int)=0xc3e25f90;5 6 void init_ttb(unsigned long *addr);7 void enable_mmu(void);8 unsigned long data_abort_init();9 void memcopy(unsigned long* dest,unsigned long* source,int len);10 void do_irq();11 void pwm_on(void);12 void pwm_off(void);13 void led_on(void);14 void led_on(void);15 16 17 18 int main()19 {20      *(unsigned long *)0x66 = do_irq;21 22     //發(fā)生異常時會進入異常模式跳轉(zhuǎn)到0 4地址處理異常事件   23     unsigned long source_addr=data_abort_init();24     //異常事件處理函數(shù)25     printf("swi_souce addr is %xn",source_addr);26     //將異常處理地址的值放到0x6427     memcopy(0x60,source_addr,0x1);28 29     enable_mmu();30     //內(nèi)存映射將0x04映射到0x6004    31 32      //step 1: cpu cpsr33       __asm__ __volatile__(34           "mrs r0, cpsrn"35           "bic r0, r0, #0x80n"http://設(shè)置CPSR的I位，將IRQ位打開36           "msr cpsr, r0n"37           ::: "r0"38       );39 40       //step 2: GIC 41       ICCICR_CPU0 = 1;//CPU接口控制寄存器42       ICCPMR_CPU0 = 0xff;//中斷優(yōu)先標(biāo)志寄存器43 44      //7545      ICDDCR = 1;46      //ICDIPR0_CPU0 = (0x00 << 0);47      ICDIPR18_CPU0 = (0x0 << 24);48      //ICDIPTR0_CPU0 = 1;49      ICDIPTR18_CPU0 = (0x1 << 24);50      //ICDISER0_CPU0 = (1 << 0);51      ICDISER2_CPU0 = (1 << 11);52 53      //step 3: interrupt source watchdog54      WTCON = 0  (1 << 2)  (3 << 3)  (1 << 5)  (250 << 8);55      WTCNT = 0x8;56      WTDAT = 0x1;57 58     printf("welcome back! n");59 60 61 }62 63 void pwm_on(void)64     {65         GPD0CON &= ~0xffff;66         GPD0CON = 0x1;//配置寄存器為267         GPD0DAT = 0x1;//date=0xf68     }69 70 void pwm_off(void)71     {72         GPD0CON &= ~0xffff;73         GPD0CON = 0x0;74     //  GPD0DAT &=0x0 ;//date=0xf75 76     }77 void led_off(void)78     {79         GPM4CON &= ~0xffff;//清零80         GPM4CON = 0x0;//03位清零81         GPM4DAT = 0x0;//date=0xf關(guān)閉置一82     }83 void led_on(void)84     {85         GPM4CON &= ~0xffff;86         GPM4CON = 0x1;//配置寄存器3-0--3-3全為1，全為輸出模式87         GPM4DAT &= ~0xf;//打開置0-4位為088     }89 90 void do_irq()91     {92         unsigned long data = ICCIAR_CPU0;93         unsigned long irq_id = data & 0x3ff;94         unsigned long cpu_id = (data >> 10) & 0x7;95         ICCEOIR_CPU0 = irq_id  (cpu_id << 10);96         printf("irq is %d, cpu is %dn", irq_id, cpu_id);97 98          pwm_on();99          led_on();100         printf("hello dog!n");101          delay(6);102          pwm_off();103          led_off();104         WTCLRINT = 0x1;105     }106 107 void memcopy(unsigned long* dest, unsigned long* source,int len)108 {109     int i=0;;110     for(i=0;i> 20] = pa  2;217         //2的目的是將0-2位置為10此時將是小頁模式4K218     }219 220     //00-10   ====  6070221     for(va=0x00; va<=0x10; va+=0x100){pa = va+0x60;223         addr[va >> 20] = pa  2;224     }225 226     //10-14   ====  1014227     for(va=0x10; va<=0x14; va+=0x100){228         pa = va;229         addr[va >> 20] = pa  2;230     }231 232     //30-40   ====  5060233     for(va=0x30; va<0x40; va+=0x100){234         pa = va + 0x20;235         addr[va >> 20] = pa  2;236     }237 }

主要看主函數(shù)部分：

39
40 //step 2: GIC
41 ICCICR_CPU0 = 1;//CPU接口控制寄存器
42 ICCPMR_CPU0 = 0xff;//中斷優(yōu)先標(biāo)志寄存器
43
44 //75
45 ICDDCR = 1;
46 //ICDIPR0_CPU0 = (0x00 << 0);
47 ICDIPR18_CPU0 = (0x0 << 24);
48 //ICDIPTR0_CPU0 = 1;
49 ICDIPTR18_CPU0 = (0x1 << 24);
50 //ICDISER0_CPU0 = (1 << 0);
51 ICDISER2_CPU0 = (1 << 11);
52
53 //step 3: interrupt source watchdog
54 WTCON = 0 (1 << 2) (3 << 3) (1 << 5) (250 << 8);
55 WTCNT = 0x8;
56 WTDAT = 0x1;
57
58 printf("welcome back! n");
還有：

90 void do_irq()
91 {
92 unsigned long data = ICCIAR_CPU0;
93 unsigned long irq_id = data & 0x3ff;
94 unsigned long cpu_id = (data >> 10) & 0x7;
95 ICCEOIR_CPU0 = irq_id (cpu_id << 10);
96 printf("irq is %d, cpu is %dn", irq_id, cpu_id);
97
98 pwm_on();
99 led_on();
100 printf("hello dog!n");
101 delay(6);
102 pwm_off();
103 led_off();
104 WTCLRINT = 0x1;
105 }
其中，各個寄存器詳見：1352芯片手冊。

運行成功：

將會發(fā)現(xiàn)板子，各一段時間就會叫一次。LED會閃爍一次！

改變WTDAT的值就會修改叫的頻率！

關(guān)鍵詞： ARM看門狗程

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