1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
|
; * ----------------------------------------------------------------------------
; * ATMEL Microcontroller Software Support
; * ----------------------------------------------------------------------------
; * Copyright (c) 2008, Atmel Corporation
; *
; * All rights reserved.
; *
; * Redistribution and use in source and binary forms, with or without
; * modification, are permitted provided that the following conditions are met:
; *
; * - Redistributions of source code must retain the above copyright notice,
; * this list of conditions and the disclaimer below.
; *
; * Atmel's name may not be used to endorse or promote products derived from
; * this software without specific prior written permission.
; *
; * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
; * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
; * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
; * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
; * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
; * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
; * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
; * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
; * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
; * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
; * ----------------------------------------------------------------------------
; KEIL startup file for AT91SAM9G20 microcontrollers.
; ------------------------------------------------------------------------------
; Definitions
; ------------------------------------------------------------------------------
; Standard definitions of Mode bits and Interrupt (I & F) flags in PSRs
ARM_MODE_USR EQU 0x10
ARM_MODE_FIQ EQU 0x11
ARM_MODE_IRQ EQU 0x12
ARM_MODE_SVC EQU 0x13
ARM_MODE_ABT EQU 0x17
ARM_MODE_UND EQU 0x1B
ARM_MODE_SYS EQU 0x1F
I_BIT EQU 0x80 ; when I bit is set, IRQ is disabled
F_BIT EQU 0x40 ; when F bit is set, FIQ is disabled
AT91C_BASE_AIC EQU 0xFFFFF000
AIC_IVR EQU 0x100
AIC_EOICR EQU 0x130
UND_Stack_Size EQU 0x00000000
SVC_Stack_Size EQU 0x00000100
ABT_Stack_Size EQU 0x00000000
FIQ_Stack_Size EQU 0x00000000
IRQ_Stack_Size EQU 0x00000080
USR_Stack_Size EQU 0x00000400
PRESERVE8
; Area Definition and Entry Point
; Startup Code must be linked first at Address at which it expects to run.
AREA VECTOR, CODE
ARM
; Exception Vectors
Vectors
LDR pc,=resetHandler
undefVector
b undefVector ; Undefined instruction
swiVector
b swiVector ; Software interrupt
prefetchAbortVector
b prefetchAbortVector ; Prefetch abort
dataAbortVector
b dataAbortVector ; Data abort
reservedVector
b reservedVector ; Reserved for future use
irqVector
b irqHandler ; Interrupt
fiqVector
; Fast interrupt
;------------------------------------------------------------------------------
; Handles a fast interrupt request by branching to the address defined in the
; AIC.
;------------------------------------------------------------------------------
fiqHandler
b fiqHandler
;------------------------------------------------------------------------------
; Handles incoming interrupt requests by branching to the corresponding
; handler, as defined in the AIC. Supports interrupt nesting.
;------------------------------------------------------------------------------
irqHandler
; Save interrupt context on the stack to allow nesting */
SUB lr, lr, #4
STMFD sp!, {lr}
MRS lr, SPSR
STMFD sp!, {r0,r1,lr}
; Write in the IVR to support Protect Mode */
LDR lr, =AT91C_BASE_AIC
LDR r0, [r14, #AIC_IVR]
STR lr, [r14, #AIC_IVR]
; Branch to interrupt handler in Supervisor mode */
MSR CPSR_c, #ARM_MODE_SVC
STMFD sp!, {r1-r4, r12, lr}
MOV lr, pc
BX r0
LDMIA sp!, {r1-r4, r12, lr}
MSR CPSR_c, #ARM_MODE_IRQ | I_BIT
; Acknowledge interrupt */
LDR lr, =AT91C_BASE_AIC
STR lr, [r14, #AIC_EOICR]
; Restore interrupt context and branch back to calling code
LDMIA sp!, {r0,r1,lr}
MSR SPSR_cxsf, lr
LDMIA sp!, {pc}^
;------------------------------------------------------------------------------
; After a reset, execution starts here, the mode is ARM, supervisor
; with interrupts disabled.
; Initializes the chip and branches to the main() function.
;------------------------------------------------------------------------------
AREA cstartup, CODE
ENTRY ; Entry point for the application
; Reset Handler
EXPORT resetHandler
IMPORT |Image$$Fixed_region$$Limit|
IMPORT |Image$$Relocate_region$$Base|
IMPORT |Image$$Relocate_region$$ZI$$Base|
IMPORT |Image$$Relocate_region$$ZI$$Limit|
IMPORT |Image$$ARM_LIB_STACK$$Base|
IMPORT |Image$$ARM_LIB_STACK$$ZI$$Limit|
; Perform low-level initialization of the chip using LowLevelInit()
IMPORT LowLevelInit
resetHandler
; Set pc to actual code location (i.e. not in remap zone)
LDR pc, =label
label
; Set up temporary stack (Top of the SRAM)
LDR r0, = |Image$$ARM_LIB_STACK$$ZI$$Limit|
MOV sp, r0
; Call Low level init
LDR r0, =LowLevelInit
MOV lr, pc
BX r0
;Initialize the Relocate_region segment
LDR r0, = |Image$$Fixed_region$$Limit|
LDR r1, = |Image$$Relocate_region$$Base|
LDR r3, = |Image$$Relocate_region$$ZI$$Base|
CMP r0, r1
BEQ %1
; Copy init data
0 CMP r1, r3
LDRCC r2, [r0], #4
STRCC r2, [r1], #4
BCC %0
1 LDR r1, =|Image$$Relocate_region$$ZI$$Limit|
MOV r2, #0
2 CMP r3, r1
STRCC r2, [r3], #4
BCC %2
; Setup Stack for each mode
LDR R0, = |Image$$ARM_LIB_STACK$$ZI$$Limit|
; Enter IRQ Mode and set its Stack Pointer
MSR CPSR_c, #ARM_MODE_IRQ:OR:I_BIT:OR:F_BIT
MOV SP, R0
SUB R4, SP, #IRQ_Stack_Size
; Supervisor mode (interrupts enabled)
MSR CPSR_c, #ARM_MODE_SVC | F_BIT
MOV SP, R4
; Enter the C code
IMPORT __main
LDR R0, =__main
BX R0
loop4
B loop4
END
|
