GNU ARM汇编--(八)s3c2440的watchdog

1. e,0@关掉重启信号
3. .equWTDAT,0x53000004
4. .equCount_reload,50000@定时器定为2SPCLK=100MPCLK/(Pre_scaler+1)/clock_select=100M/(249+1)/16=25k50000/25k=2s
6. .equWTCNT,0x53000008
7. .equCount,50000
13. .global_start
14. _start:breset
15. ldrpc,_undefined_instruction
16. ldrpc,_software_interrupt
17. ldrpc,_prefetch_abort
18. ldrpc,_data_abort
19. ldrpc,_not_used
20. @birq
21. ldrpc,_irq
22. ldrpc,_fiq
26. _undefined_instruction:.wordundefined_instruction
27. _software_interrupt:.wordsoftware_interrupt
28. _prefetch_abort:.wordprefetch_abort
29. _data_abort:.worddata_abort
30. _not_used:.wordnot_used
31. _irq:.wordirq
32. _fiq:.wordfiq
34. .balignl16,0xdeadbeef
36. reset:
39. ldrr3,=WTCON
40. movr4,#0x0
41. strr4,[r3]@disablewatchdog
43. ldrr0,=GPBCON
44. ldrr1,=0x15400
45. strr1,[r0]
47. ldrr2,=GPBDAT
48. ldrr1,=0x160
49. strr1,[r2]
51. blclock_setup
52. bldelay
55. msrcpsr_c,#0xd2@进入中断模式
56. ldrsp,=3072@中断模式的栈指针定义
58. msrcpsr_c,#0xd3@进入系统模式
59. ldrsp,=4096@设置系统模式的栈指针
61. @--------------------------------------------
63. ldrr0,=GPBUP
64. ldrr1,=0x03f0
65. strr1,[r0]
67. ldrr0,=GPFCON
68. ldrr1,=0x2ea@0x2
69. strr1,[r0]
71. ldrr0,=EXTINT0
72. @ldrr1,=0x8f888@0x0@0x8f888@~(7|(7<4)|(7<8)|(7<16))//低电平触发中断
73. ldrr1,=0xafaaa@0x0@0x8f888//下降沿触发中断
74. strr1,[r0]
76. ldrr0,=EINTPEND
77. ldrr1,=0xf0@0b10000
78. strr1,[r0]
80. ldrr0,=EINTMASK
81. ldrr1,=0x00@0b00000
82. strr1,[r0]
86. ldrr0,=SRCPND
87. ldrr1,=0x3ff@0x1@0b11111
88. strr1,[r0]
90. ldrr0,=SUBSRCPND
91. ldrr1,=0x1<13
92. strr1,[r0]
94. ldrr0,=INTPND
95. ldrr1,=0x3ff@0x1@0b11111
96. strr1,[r0]
98. ldrr0,=INTSUBMSK
99. ldrr1,=0x0<13
100. strr1,[r0]
102. ldrr0,=INTMSK
103. ldrr1,=0xfffff000@0b00000
104. strr1,[r0]
106. MRSr1,cpsr
107. BICr1,r1,#0x80
108. MSRcpsr_c,r1
111. blmain
113. irq:
114. sublr,lr,#4
115. stmfdsp!,{r0-r12,lr}
118. blirq_isr
119. ldmfdsp!,{r0-r12,pc}^
122. irq_isr:
124. ldrr2,=GPBDAT
125. ldrr1,=0x0e0
126. strr1,[r2]
129. ldrr0,=EINTPEND
130. ldrr1,=0xf0
131. strr1,[r0]
133. ldrr0,=SRCPND
134. ldrr1,=0x3ff@0b11111
135. strr1,[r0]
137. ldrr0,=SUBSRCPND
138. ldrr1,=0x1<13
139. strr1,[r0]
141. ldrr0,=INTPND
142. ldrr1,=0x3ff@0b11111
143. strr1,[r0]
145. movpc,lr
148. delay:
150. ldrr3,=0xffffff
152. delay1:
153. subr3,r3,#1
155. cmpr3,#0x0
157. bnedelay1
159. movpc,lr
162. clock_setup:
164. ldrr0,=LOCKTIME
165. ldrr1,=0xffffffff
166. strr1,[r0]
168. ldrr0,=CLKdivN
169. ldrr1,=(divN_UPLL<3)|(HdivN<1)|(PdivN<0)
170. strr1,[r0]
172. ldrr0,=UPLLCON
173. ldrr1,=(U_Mdiv<12)|(U_Pdiv<4)|(U_Sdiv<0)@Fin=12MUPLL=48M
174. strr1,[r0]
175. nop
176. nop
177. nop
178. nop
179. nop
180. nop
181. nop
182. ldrr0,=MPLLCON
183. ldrr1,=(M_Mdiv<12)|(M_Pdiv<4)|(M_Sdiv<0)@Fin=12MFCLK=400M
184. strr1,[r0]
188. movpc,lr
191. main:
193. ldrr0,=WTDAT
194. ldrr1,=Count_reload
195. strr1,[r0]
197. ldrr0,=WTCNT
198. ldrr1,=Count
199. strr1,[r0]
201. ldrr0,=WTCON
202. ldrr1,=(Pre_scaler<8)|(wd_timer<5)|(clock_select<3)|(int_gen<2)|(reset_enable)
203. strr1,[r0]
204. ledloop:
206. ldrr1,=0x1c0
207. strr1,[r2]
208. bldelay
210. ldrr1,=0x1a0
211. strr1,[r2]
212. bldelay
214. ldrr1,=0x160
215. strr1,[r2]
216. bldelay
218. ldrr1,=0x0e0
219. strr1,[r2]
220. bldelay
222. bledloop
227. undefined_instruction:
228. nop
229. software_interrupt:
230. nop
231. prefetch_abort:
232. nop
233. data_abort:
234. nop
235. not_used:
236. nop
237. fiq:
238. nop

稍微该一下上面的代码:

.equ int_gen, 0 @关中断
.equ reset_enable, 1 @打开重启信号

打开重启信号,则可以看到每隔2s系统就重启一次.

如果在循环中加入:

ldr r0, =WTCNT @喂狗
ldr r1, =Count
str r1, [r0]

那么,这又是一个标准的流水灯了.而且是有watchdog保护的流水灯了.