所以，我最近购买了一 block SAMC21 Xplained 开发板，开始尝试学习 ARM 编程。我以前的经验主要是与 PIC 相关。作为示例应用程序，我启动了一个针对 SAMC21 Xplained 板的 ASF Board 项目，并编写了以下主要函数:
#include <asf.h>
#include <stdbool.h>
int main (void) {
system_init();
SysTick_Config(SystemCoreClock/1000);
system_interrupt_enable(SYSTEM_INTERRUPT_SYSTICK);
while(true);
}
void SysTick_Handler(void) {
port_pin_toggle_output_level(LED_0_PIN);
}
当我开始调试时，我成功到达 main 并执行 system_init() 函数。此后，程序计数器将永远挂起。反汇编如下所示:
int main (void) {
000004D0 ??? Memory out of bounds or read error
system_init();
000004D2 ldr r3, #60
000004D4 blx r3
SysTick_Config(SystemCoreClock/1000);
000004D6 ldr r3, #60
000004D8 ldr r0, [r3]
000004DA movs r1, #250
000004DC lsls r1, r1, #2
000004DE ldr r3, #56
000004E0 blx r3
if ((ticks - 1) > SysTick_LOAD_RELOAD_Msk) return (1); /* Reload value impossible */
000004E2 subs r0, #1
000004E4 ldr r3, #52
000004E6 cmp r0, r3
000004E8 bhi #26
SysTick->LOAD = ticks - 1; /* set reload register */
000004EA ldr r3, #52
000004EC str r0, [r3, #4]
SCB->SHP[_SHP_IDX(IRQn)] = (SCB->SHP[_SHP_IDX(IRQn)] & ~(0xFF << _BIT_SHIFT(IRQn))) |
000004EE ldr r2, #52
000004F0 ldr r0, [r2, #32]
000004F2 lsls r0, r0, #8
000004F4 lsrs r0, r0, #8
000004F6 movs r1, #192
000004F8 lsls r1, r1, #24
000004FA orrs r1, r0
000004FC str r1, [r2, #32]
SysTick->VAL = 0; /* Load the SysTick Counter Value */
000004FE movs r2, #0
00000500 str r2, [r3, #8]
SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk |
00000502 movs r2, #7
00000504 str r2, [r3]
NVIC->ISER[0] = (uint32_t)(1 << ((uint32_t)vector & 0x0000001f));
00000506 movs r2, #128
00000508 lsls r2, r2, #24
0000050A ldr r3, #28
0000050C str r2, [r3]
0000050E b #-4 // Debugger PC Hangs
00000510 lsls r1, r2, #16
00000512 movs r0, r0
00000514 movs r4, r0
00000516 movs r0, #0
00000518 lsls r1, r7, #20
0000051A movs r0, r0
0000051C ??? Memory out of bounds or read error
0000051E lsls r7, r7, #3
00000520 b #32
00000522 b #0
00000524 ??? Memory out of bounds or read error
00000526 b #0
00000528 b #512
0000052A b #0
port_base->OUTTGL.reg = pin_mask;
0000052C movs r2, #128
0000052E lsls r2, r2, #8
00000530 movs r3, #130
00000532 lsls r3, r3, #23
00000534 str r2, [r3, #28]
}
00000536 bx lr
我已向 PC 挂起的行添加了注释 (0x0000050E)。我很困惑，因为看起来 b #-4 汇编指令通过重复分支到自身而表现正确。我不明白的是为什么它首先存在。
编辑 首先感谢大家的热心回复!其次，我应该包含更多的代码(对此感到抱歉)，但不确定哪些是相关的。我已经编辑了上面的代码以显示整个 main.c 文件。看起来代码中的 while(true) 几乎被放错了地方，但我仍然在努力理解它。
还从我的 .lss 文件中添加一些(希望如此!)有用的片段:
00000000 <_sfixed>:
* Initialize the System and update the SystemCoreClock variable.
*/
void SystemInit(void)
{
// Keep the default device state after reset
SystemCoreClock = __SYSTEM_CLOCK;
0: 20002030 .word 0x20002030
4: 00000441 .word 0x00000441
return;
}
8: 0000043d .word 0x0000043d
c: 0000043d .word 0x0000043d
...
2c: 0000043d .word 0x0000043d
...
38: 0000043d .word 0x0000043d
3c: 0000052d .word 0x0000052d
40: 0000043d .word 0x0000043d
44: 0000043d .word 0x0000043d
48: 0000043d .word 0x0000043d
4c: 0000043d .word 0x0000043d
50: 0000043d .word 0x0000043d
54: 0000043d .word 0x0000043d
58: 0000043d .word 0x0000043d
5c: 0000043d .word 0x0000043d
60: 0000043d .word 0x0000043d
64: 0000043d .word 0x0000043d
68: 0000043d .word 0x0000043d
6c: 0000043d .word 0x0000043d
70: 0000043d .word 0x0000043d
74: 0000043d .word 0x0000043d
78: 0000043d .word 0x0000043d
7c: 0000043d .word 0x0000043d
80: 0000043d .word 0x0000043d
84: 0000043d .word 0x0000043d
88: 0000043d .word 0x0000043d
8c: 0000043d .word 0x0000043d
90: 0000043d .word 0x0000043d
94: 0000043d .word 0x0000043d
98: 0000043d .word 0x0000043d
9c: 0000043d .word 0x0000043d
a0: 0000043d .word 0x0000043d
a4: 0000043d .word 0x0000043d
a8: 0000043d .word 0x0000043d
ac: 0000043d .word 0x0000043d
b0: 0000043d .word 0x0000043d
b4: 0000043d .word 0x0000043d
b8: 0000043d .word 0x0000043d
000004d0 <main>:
#include <asf.h>
#include <stdbool.h>
int main (void) {
4d0: b508 push {r3, lr}
system_init();
4d2: 4b0f ldr r3, [pc, #60] ; (510 <main+0x40>)
4d4: 4798 blx r3
SysTick_Config(SystemCoreClock/1000);
4d6: 4b0f ldr r3, [pc, #60] ; (514 <main+0x44>)
4d8: 6818 ldr r0, [r3, #0]
4da: 21fa movs r1, #250 ; 0xfa
4dc: 0089 lsls r1, r1, #2
4de: 4b0e ldr r3, [pc, #56] ; (518 <main+0x48>)
4e0: 4798 blx r3
must contain a vendor-specific implementation of this function.
*/
__STATIC_INLINE uint32_t SysTick_Config(uint32_t ticks)
{
if ((ticks - 1) > SysTick_LOAD_RELOAD_Msk) return (1); /* Reload value impossible */
4e2: 3801 subs r0, #1
4e4: 4b0d ldr r3, [pc, #52] ; (51c <main+0x4c>)
4e6: 4298 cmp r0, r3
4e8: d80d bhi.n 506 <main+0x36>
SysTick->LOAD = ticks - 1; /* set reload register */
4ea: 4b0d ldr r3, [pc, #52] ; (520 <main+0x50>)
4ec: 6058 str r0, [r3, #4]
\param [in] priority Priority to set.
*/
__STATIC_INLINE void NVIC_SetPriority(IRQn_Type IRQn, uint32_t priority)
{
if(IRQn < 0) {
SCB->SHP[_SHP_IDX(IRQn)] = (SCB->SHP[_SHP_IDX(IRQn)] & ~(0xFF << _BIT_SHIFT(IRQn))) |
4ee: 4a0d ldr r2, [pc, #52] ; (524 <main+0x54>)
4f0: 6a10 ldr r0, [r2, #32]
4f2: 0200 lsls r0, r0, #8
4f4: 0a00 lsrs r0, r0, #8
4f6: 21c0 movs r1, #192 ; 0xc0
4f8: 0609 lsls r1, r1, #24
4fa: 4301 orrs r1, r0
4fc: 6211 str r1, [r2, #32]
{
if ((ticks - 1) > SysTick_LOAD_RELOAD_Msk) return (1); /* Reload value impossible */
SysTick->LOAD = ticks - 1; /* set reload register */
NVIC_SetPriority (SysTick_IRQn, (1<<__NVIC_PRIO_BITS) - 1); /* set Priority for Systick Interrupt */
SysTick->VAL = 0; /* Load the SysTick Counter Value */
4fe: 2200 movs r2, #0
500: 609a str r2, [r3, #8]
SysTick->CTRL = SysTick_CTRL_CLKSOURCE_Msk |
502: 2207 movs r2, #7
504: 601a str r2, [r3, #0]
* \param[in] vector Interrupt vector to enable
*/
static inline void system_interrupt_enable(
const enum system_interrupt_vector vector)
{
NVIC->ISER[0] = (uint32_t)(1 << ((uint32_t)vector & 0x0000001f));
506: 2280 movs r2, #128 ; 0x80
508: 0612 lsls r2, r2, #24
50a: 4b07 ldr r3, [pc, #28] ; (528 <main+0x58>)
50c: 601a str r2, [r3, #0]
50e: e7fe b.n 50e <main+0x3e>
510: 00000411 .word 0x00000411
514: 20000004 .word 0x20000004
518: 00000539 .word 0x00000539
51c: 00ffffff .word 0x00ffffff
520: e000e010 .word 0xe000e010
524: e000ed00 .word 0xe000ed00
528: e000e100 .word 0xe000e100
0000052c <SysTick_Handler>:
{
PortGroup *const port_base = port_get_group_from_gpio_pin(gpio_pin);
uint32_t pin_mask = (1UL << (gpio_pin % 32));
/* Toggle pin output level */
port_base->OUTTGL.reg = pin_mask;
52c: 2280 movs r2, #128 ; 0x80
52e: 0212 lsls r2, r2, #8
530: 2382 movs r3, #130 ; 0x82
532: 05db lsls r3, r3, #23
534: 61da str r2, [r3, #28]
while(true);
}
void SysTick_Handler(void) {
port_pin_toggle_output_level(LED_0_PIN);
}
536: 4770 bx lr
最佳答案
最近遇到了同样的系统问题。通过分析和更改链接描述文件 (.ld)，问题得到了解决。我正在使用自定义链接器脚本。 检查您的链接器脚本、MSR、 vector 地址(位于位置 0x0000003C)
关于c - Atmel Cortex-M0+ SAMC21 在 SysTick_Config 之后挂起，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32333739/