startup_stm32f10x_md.s文件中,调用了一个叫SystemInit的函数,该函数其实在system_stm32f10x.c中定义,旨在初始化系统时钟、初始化外部SRAM、设置中断向量表地址。% E# f1 J& A1 v- H ]
- void SystemInit (void)
8 n$ y: `& S' y6 E$ x - {% ?3 G, V7 ^. d; Z
- /* 使能内部高速时钟 */ V; K6 E! U" u: h
- RCC->CR |= (uint32_t)0x00000001;
, B( i; g! k/ t4 ]+ g! n - ; W6 L( }8 w0 L0 J, C/ [4 P( p
- , P9 S$ O. |! m3 }4 i
- #ifndef STM32F10X_CL
* {. d2 `" ^6 P" P3 ?& h" ]! q; x - RCC->CFGR &= (uint32_t)0xF8FF0000;6 p+ k- y2 `* F, E
- #else
& c* l6 D' p1 g' h' b# R - RCC->CFGR &= (uint32_t)0xF0FF0000;1 X7 Y7 _4 ~* a# ?' W
- #endif
: X, _/ l" V C. t4 U! S& r - 4 V3 `" p6 s, R! [
- /* 禁用PLL、禁用始时钟检测、禁用外部高速时钟 */) o3 ^) x9 \2 ]9 t- j! K+ w
- RCC->CR &= (uint32_t)0xFEF6FFFF;
/ O3 L. E+ B. R i; G2 z" I" n - ! n5 [/ g$ N8 x( n
- /* 外部1-25M振荡器未被绕过 */
# f4 g3 {5 r$ d# D - RCC->CR &= (uint32_t)0xFFFBFFFF;
' E& l! \/ X1 A8 ^8 l
3 l0 e( E" y1 B" D/ d' R- /* USB预分频器PLL未分频、PLL倍频2、HSE未被分频、HSI/2作为PLL频率 */3 r1 U# p- b& _
- RCC->CFGR &= (uint32_t)0xFF80FFFF;
9 j1 S) ~1 L% c# f3 p- B - * V: j$ v0 r5 d0 ?3 f
/ ?. m& ?3 Q6 J) u& H g9 @" T7 M- /* 禁用时钟中断寄存器 */
8 { G& s* [2 H0 s - $ n8 N+ J1 G X1 T+ c6 ~) J
- #ifdef STM32F10X_CL
9 ~8 f9 o/ N3 W0 r7 z' t - RCC->CR &= (uint32_t)0xEBFFFFFF;, J9 K/ W/ H0 c' h6 F+ Z+ R
$ d; e* f9 S6 K2 p- RCC->CIR = 0x00FF0000;
- t L8 B, t) H& ~9 _" J: {1 s - ) c9 y6 j5 s! f E4 |
- RCC->CFGR2 = 0x00000000; m, |4 l2 M# Q- K5 q! ^
- #elif defined (STM32F10X_LD_VL) || defined (STM32F10X_MD_VL) || (defined STM32F10X_HD_VL)/ U5 `8 w5 e f0 o2 O3 q+ N
- RCC->CIR = 0x009F0000;9 H% e! D7 Y4 w/ F x' C" u
- * |: M# i+ x, j/ |1 N. T3 J2 _
- /* Reset CFGR2 register */) T3 `$ Q" z3 W- G
- RCC->CFGR2 = 0x00000000;
) W4 `+ I6 g' P/ Y - #else6 P T4 u. U* y# a$ ]
- RCC->CIR = 0x009F0000;
4 J9 k$ y! x3 c0 G - #endif /* STM32F10X_CL */
/ A: y; _8 y5 `8 e5 F- ^
1 W9 j2 Y; q1 @9 l5 G6 X# [
) |3 Q, Q0 R. L* s& w; c4 v- /* 设置外部SRAM */- ~/ a2 T! Y( A4 j
- #if defined (STM32F10X_HD) || (defined STM32F10X_XL) || (defined STM32F10X_HD_VL)6 X1 [* p/ J! \, p3 s/ }2 U
- #ifdef DATA_IN_ExtSRAM
% z8 U' q3 K$ H6 c - SystemInit_ExtMemCtl();
# A5 g( J! {' h3 n# N) C - #endif /* DATA_IN_ExtSRAM */, G' d7 a& z' g Q2 s
- #endif
5 x% T. [4 q4 m! I - 3 d- F8 R. F! I( C% W
" y; w# \4 A& X3 j$ [2 e- /* 配置系统时钟 *// U) J1 N. F# c+ l
- SetSysClock();
1 b# W! m$ X) f - / V! a- o) E/ c6 h/ Y9 @
6 R3 h! s4 A5 f& G- /*中断向量偏移地址设置 */
5 l& Z& C4 @5 w$ x `, `% m$ g - / f! z9 ~& k/ S- \
- #ifdef VECT_TAB_SRAM. o% ~' k+ J+ E" h
- SCB->VTOR = SRAM_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal SRAM. */
$ m$ m0 s- f) @' ^8 H - #else
+ w. q; ?6 C" E& g" J% ? - SCB->VTOR = FLASH_BASE | VECT_TAB_OFFSET; /* Vector Table Relocation in Internal FLASH. */6 i! b* c) |5 w# t5 {" g
- #endif $ B+ X- t/ V! Q
- }
复制代码 9 G' Z7 `: J7 |
5 ^6 s0 @2 K$ d8 N7 B
& o- q% a2 J! M. [7 \' d |