DTR电平置低(-3--12V),复位
RTS置高(+3-+12V),选择进入BootLoader
...延时100毫秒
DTR电平变高(+3-+12V)释放复位
RTS维持高
开始连接...5, 接收到:79 1F
在串口COM6连接成功@115200bps，耗时795毫秒
芯片内BootLoader版本号：3.1
芯片PID：00000419  STM32F4xxx_43xx
读出的选项字节:
EFAA1055EFAA1055FF3F00C0FF3F00C0
开始全片擦除(全片擦除时间会比较长，请耐心等候!)
全片擦除成功
开始去除写保护
去除写保护成功
DTR电平置低(-3--12V),复位
RTS置高(+3-+12V),选择进入BootLoader
...延时100毫秒
DTR电平变高(+3-+12V)释放复位
RTS维持高
开始连接...5, 接收到:79 1F
在串口COM6连接成功@115200bps，耗时842毫秒
芯片内BootLoader版本号：3.1
芯片PID：00000419  STM32F4xxx_43xx
读出的选项字节:
EFAA1055EFAA1055FF3F00C0FF3F00C0
第889毫秒，已准备好
共写入679KB,进度100%,耗时280193毫秒
写入选项字节： FF AA 00 55 FF AA 00 55 FF FF 00 00 FF FF 00 00
成功写入选项字节
写入的选项字节:
FFAA0055FFAA0055FFFF0000FFFF0000
从08000000开始运行失败...可能是因为刚写了选项字节!!!
www.mcuisp.com(全脱机手持编程器EP968,全球首创)向您报告，命令执行完毕，一切正常

读器件信息：

现在，我正在尝试点亮LED灯。

【程序】
#include "stm32f4xx.h"

void SystemInit(void)
{
}

int main(void)
{
    RCC_AHB1ENR |= (1 << 7);
   
    GPIOH_MODER &= ~(0x03 << (2 * 10));
    GPIOH_MODER |= (1 << 2 * 10);
   
    GPIOH_OTYPER &= ~(1 << 1 * 10);
    GPIOH_OTYPER |= (0 << 1 * 10);
   
    GPIOH_OSPEEDR &= ~(0x03 << 2 * 10);
    GPIOH_OSPEEDR |= (0 << 2 * 10);
   
    GPIOH_PUPDR &= ~(0x03 << 2 * 10);
    GPIOH_PUPDR |= (1 << 2 * 10);
   
    GPIOH_BSSR |= (1 << 16 << 10);
   
    while (1);
    return 0;
}

可见，STM32点亮LED要比C51和AVR复杂很多倍。

【编译错误】
*** Using Compiler 'V5.06 update 1 (build 61)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Build target 'Target 1'
compiling led.c...
C:\Keil_v5\ARM\PACK\Keil\STM32F4xx_DFP\2.7.0\Drivers\CMSIS\Device\ST\STM32F4xx\Include\stm32f429xx.h(192): error:  #5: cannot open source input file "core_cm4.h": No such file or directory
  #include "core_cm4.h"             /* Cortex-M4 processor and core peripherals */
led.c: 0 warnings, 1 error
".\Objects\led.axf" - 1 Error(s), 0 Warning(s).
Target not created.
Build Time Elapsed:  00:00:14

*** Using Compiler 'V5.06 update 1 (build 61)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Build target 'Target 1'
compiling led.c...
led.c(9): error:  #20: identifier "RCC_AHB1ENR" is undefined
      RCC_AHB1ENR |= (1 << 7);
led.c(11): error:  #20: identifier "GPIOH_MODER" is undefined
      GPIOH_MODER &= ~(0x03 << (2 * 10));
led.c(14): error:  #20: identifier "GPIOH_OTYPER" is undefined
      GPIOH_OTYPER &= ~(1 << 1 * 10);
led.c(17): error:  #20: identifier "GPIOH_OSPEEDR" is undefined
      GPIOH_OSPEEDR &= ~(0x03 << 2 * 10);
led.c(20): error:  #20: identifier "GPIOH_PUPDR" is undefined
      GPIOH_PUPDR &= ~(0x03 << 2 * 10);
led.c(23): error:  #20: identifier "GPIOH_BSSR" is undefined
      GPIOH_BSSR |= (1 << 16 << 10);
led.c(26): warning:  #111-D: statement is unreachable
      return 0;
led.c(27): warning:  #1-D: last line of file ends without a newline
  }
led.c: 2 warnings, 6 errors
".\Objects\led.axf" - 6 Error(s), 2 Warning(s).
Target not created.
Build Time Elapsed:  00:00:01

#include "stm32f4xx.h"

//#define PERIPH_BASE ((unsigned int)0x40000000)
#define AHB1PERIPH_BASE (PERIPH_BASE + 0x00020000)
#define GPIOH_BASE (AHB1PERIPH_BASE + 0x1C00)
#define GPIOH_MODER *(unsigned int*)(GPIOH_BASE+0x00)
#define GPIOH_OTYPER *(unsigned int*)(GPIOH_BASE+0x04)
#define GPIOH_OSPEEDR *(unsigned int*)(GPIOH_BASE+0x08)
#define GPIOH_PUPDR *(unsigned int*)(GPIOH_BASE+0x0C)
#define GPIOH_IDR *(unsigned int*)(GPIOH_BASE+0x10)
#define GPIOH_ODR *(unsigned int*)(GPIOH_BASE+0x14)
#define GPIOH_BSRR *(unsigned int*)(GPIOH_BASE+0x18)
#define GPIOH_LCKR *(unsigned int*)(GPIOH_BASE+0x1C)
#define GPIOH_AFRL *(unsigned int*)(GPIOH_BASE+0x20)
#define GPIOH_AFRH *(unsigned int*)(GPIOH_BASE+0x24)
#define RCC_BASE (AHB1PERIPH_BASE + 0x3800)
#define RCC_AHB1ENR *(unsigned int*)(RCC_BASE+0x30)


void SystemInit(void)
{
}

int main(void)
{
    RCC_AHB1ENR |= (1 << 7);
    
    GPIOH_MODER &= ~(0x03 << (2 * 10));
    GPIOH_MODER |= (1 << 2 * 10);
    
    GPIOH_OTYPER &= ~(1 << 1 * 10);
    GPIOH_OTYPER |= (0 << 1 * 10);
    
    GPIOH_OSPEEDR &= ~(0x03 << 2 * 10);
    GPIOH_OSPEEDR |= (0 << 2 * 10);
    
    GPIOH_PUPDR &= ~(0x03 << 2 * 10);
    GPIOH_PUPDR |= (1 << 2 * 10);
    
    GPIOH_BSRR |= (1 << 16 << 10);
    
    while (1);
}

*** Using Compiler 'V5.06 update 1 (build 61)', folder: 'C:\Keil_v5\ARM\ARMCC\Bin'
Build target 'Target 1'
compiling led.c...
linking...
Program Size: Code=244 RO-data=444 RW-data=0 ZI-data=1024  
FromELF: creating hex file...
".\Objects\led.axf" - 0 Error(s), 0 Warning(s).
Build Time Elapsed:  00:00:01