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对于一个器件来说，只有实现了输入输出才能体现出它存在的价值，因此学习STM32的GPIO有着重要的意义。
        那么如何才能学好GPIO呢？那么你就要对GPIO相关的库文件进行了解。最好的方法就是实践，首先建立一个工程，然后编写GPIO的程序，不断的修改程序，并利用板载的LED观察每次修改的结果，不断的总结经验中就能学到很多知识。
        趁热打铁，我自己写的LED流水灯测试程序，代码如下：
/**
  ******************************************************************************
  * @file    main.c
  * @author  th152210
  * @version V1.0
  * @date    2012/05/07
  * @brief   four LEDs turn on/off like running water
  ******************************************************************************
  * @description
  * four LEDs turn on/off like running water
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/

#include "stm32f10x.h"

#define led    GPIOE
#define led1      GPIO_Pin_2
#define led2   GPIO_Pin_3
#define led3   GPIO_Pin_4
#define led4   GPIO_Pin_5
#define ledTurnOn(ledx) GPIO_ResetBits(led , ledx)
#define ledTurnOff(ledx) GPIO_SetBits(led , ledx)
#define ledTurnOnAll() ledTurnOn(gpioInit.GPIO_Pin)
#define ledTurnOffAll() ledTurnOff(gpioInit.GPIO_Pin)
/**
  * @brief  time delay about 0.3s
  * @param  none.
  * @retval None
  */
void delay(void)
{
 uint32_t i,j;
 for (i=0;i<1500;i++)
 {
  for (j=0;j<1000;j++)
  {
   ;
  }
 }
}
/**
  * @brief  the main process.
  * @note   cannt built without it.
  * @param  none.
  * @retval None
  */
main ()
{       
 GPIO_InitTypeDef gpioInit;
 uint16_t count0,count1,count2,count3;
 count0 = 0;
 //-----initialization------
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE, ENABLE); //enable APB2 periph
 gpioInit.GPIO_Pin = led1|led2|led3|led4;
 gpioInit.GPIO_Mode = GPIO_Mode_Out_PP;
  gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 GPIO_Init(led , &gpioInit);       //initialiazate gpio
 GPIO_SetBits(led , gpioInit.GPIO_Pin); //set pin
 GPIO_ResetBits(led , gpioInit.GPIO_Pin); //reset pin

  while (1)
   { 
  for(;count0<8;count0++)   //all LEDs light on/off together
  {
   ledTurnOnAll();
   delay();
   ledTurnOffAll();
   delay();
  }
  for(;count0<12;count0++)   //right turn on one by one
                 //and turn off all , then left...
  {
   count1=0;
   ledTurnOn (led1);
   delay();
   ledTurnOn (led2);
   delay();
   ledTurnOn (led3);
   delay();
   ledTurnOn (led4);
   delay();
   ledTurnOffAll();
   delay();

   ledTurnOn (led4);
   delay();
   ledTurnOn (led3);
   delay();
   ledTurnOn (led2);
   delay();
   ledTurnOn (led1);
   delay();
   ledTurnOffAll();
   delay();
  }
  for(;count0<16;count0++)   //right turn on one by one
                 //and left turn off one by one
  {
   count1=0;
   ledTurnOn (led1);
   delay();
   ledTurnOn (led2);
   delay();
   ledTurnOn (led3);
   delay();
   ledTurnOn (led4);
   delay();

   ledTurnOff (led4);
   delay();
   ledTurnOff (led3);
   delay();
   ledTurnOff (led2);
   delay();
   ledTurnOff (led1);
   delay();
  }
  for(;count0<17;count0++)
  {
   ledTurnOn (led1);
   delay();
   ledTurnOn (led2);
   delay();
   ledTurnOn (led3);
   delay();
   ledTurnOn (led4);
   delay();
   ledTurnOff (led1);
   delay();
   ledTurnOff (led2);
   delay();
   ledTurnOff (led3);
   delay();
   ledTurnOff (led4);
   delay();
  }
  for(;count0<21;count0++)   //left turn on one by one
                 //and right turn off one by one
  {
   count1=0;
   ledTurnOn (led4);
   delay();
   ledTurnOn (led3);
   delay();
   ledTurnOn (led2);
   delay();
   ledTurnOn (led1);
   delay();

   ledTurnOff (led1);
   delay();
   ledTurnOff (led2);
   delay();
   ledTurnOff (led3);
   delay();
   ledTurnOff (led4);
   delay();
  }
   }
}

我的串口调试程序。开始运行时，先发送一串数据。然后开始等待接收数据
（inputString()），再将接收到的数据发送（putString()）出去。我的程序如
下：

/**
  ******************************************************************************
  * @file    main.c
  * @author  th152210
  * @version V1.0
  * @date    2012/05/07
  * @brief   USART Send string "www.hi.baidu.com/th152210" per second
  ******************************************************************************
  * @description
  * USART Send string "www.hi.baidu.com/th152210" per second , and when it is
 * sending the led flashing.then USART send the string it received from the
 * computer . for example when it receive "www.hi.baidu.com/th152210" , then it
 * will send "www.hi.baidu.com/th152210" to the computer .
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/

#include "main.h"
#include "string.h"

/* Defination ----------*/
//---the port for leds---
#define led GPIOE
#define led1 GPIO_Pin_2
#define led2 GPIO_Pin_3
#define led3 GPIO_Pin_4
#define led4 GPIO_Pin_5

/********var**********/
char usartRxBuffer[256];

/**
  * @brief  time delay
  * @param  none.
  * @retval None
  */
void delay()
{
 vu32 i,j;
 for(i=0;i<9000000;i++);
}
/**
  * @brief  send a data by USART
  * @param  data : the data for sending
  * @retval none
  */
void putChar(uint16_t data)
{
 while(USART_GetFlagStatus(USART1, USART_FLAG_TXE) == RESET);//wait until empty
  USART_SendData(USART1 , data);    //send data
}
/**
  * @brief  send a string by USART
  * @param  data : the data for sending
  * @retval none
  */
void putString(char data[] , uint16_t lenth)
{
 uint16_t i;
 if(lenth == 0)
 {
  for(i = 0 ; i < strlen(data); i++)
  {
   putChar(data[i]); //send one data of data[i]
  }
 }else
 {
  for(i = 0 ; i < lenth ; i++)
  {
   putChar(data[i]); //send one data of data[i]
  }
 }
}
/**
  * @brief  receive a data
  * @param  none
  * @retval the data received
  */
uint16_t inputChar()
{
 uint16_t data;
 while(USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == RESET);//wait for the RX no empty bit become 1
 data = USART_ReceiveData(USART1);
 return data;
}
/**
  * @brief  receive a string
  * @param  the string received
  * @retval none
  */
char inputString()
{
 char data , i;
 data = (char)inputChar();
 for(i = 0; (data != 0x0D) && (i < 255); i++)
 {
  usartRxBuffer[i] = data;
  data = (char)inputChar();
 }
 if(i == 255) return 0;
 else return 1;
}
/**
  * @brief  the main
  * @param  none.
  * @retval None
  */

int main (void)
{
 GPIO_InitTypeDef gpioInit;
 USART_InitTypeDef USART_InitStructure;
 char *string;
 uint16_t data;
 //----- RCC initialization -------
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE, ENABLE); //enable APB2 periph
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 , ENABLE);
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
 //RCC_GetClockFreq(&RCC_ClockFreq);
 //----- IO initialization -----
 gpioInit.GPIO_Pin = led1|led2|led3|led4;
 gpioInit.GPIO_Mode = GPIO_Mode_Out_PP;
  gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 GPIO_Init(led , &gpioInit);       //initialiazate gpio
 GPIO_SetBits(led , gpioInit.GPIO_Pin); //Set pin
 //GPIO_ResetBits(led , gpioInit.GPIO_Pin); //Reset pin

 /* Configure USART1 Tx (PA.09) as alternate push-pull */
 gpioInit.GPIO_Pin = GPIO_Pin_9;
 gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 gpioInit.GPIO_Mode = GPIO_Mode_AF_PP;
 GPIO_Init(GPIOA, &gpioInit);

 //----- UART initialization ----
  //0-----串口参数配置------
  USART_InitStructure.USART_BaudRate = 19200;                 //设置波特率为19200
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;  //设置数据位为8位
  USART_InitStructure.USART_StopBits = USART_StopBits_1;       //设置停止位为1位
  USART_InitStructure.USART_Parity = USART_Parity_No;          //无奇偶校验   
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //没有硬件流控
  USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;      //send and receive mode
 //0-----------------------
  USART_Init(USART1, &USART_InitStructure); //initialization USART1
 USART_Cmd(USART1 , ENABLE);  //enable USART1 modulation
 //USART_ITConfig(USART1, USART_IT_RXNE, DISABLE); //disable USART1 interruption

 //查询方式发送数据
 string = "www.hi.baidu.com/th152210\n";
 GPIO_ResetBits(led , led1|led2); //Reset pin
  putString(string,0); //send string
 GPIO_SetBits(led , led1|led2);   //Set pin
 while(1)
 {
  GPIO_ResetBits(led , led3|led4); //Reset pin1 2
  inputString();
  //data = inputChar();
  //delay();
  GPIO_SetBits(led , led3|led4);   //Set pin1 2
  //putString(string,6);
  GPIO_ResetBits(led , led1|led2); //Reset pin3 4
  //putChar(data); 
  putString(usartRxBuffer,0);
  GPIO_SetBits(led , led1|led2);   //Set pin3 4
 }
}

板子DIY中的说明。自己感觉还是挺有才的。
5月23日有更新，电容电阻，按键又添加了很多，所用到的基本补全。未采购的器件CAN没有焊接，其它除少量去耦电容未焊接，其它都喊上了。0欧电阻嫌麻烦没焊接的直接用焊锡短路了。

中断方式的USART程序调试成功，部分代码如下：

main.C中的相关代码:
int main (void)
{
 GPIO_InitTypeDef gpioInit;
 USART_InitTypeDef USART_InitStructure;
 NVIC_InitTypeDef NVIC_InitStructure;
 char *string;
 //----- RCC initialization -------
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_GPIOE | RCC_APB2Periph_AFIO |
             RCC_APB2Periph_USART1 , ENABLE);
 //RCC_GetClockFreq(&RCC_ClockFreq);
 //----- IO initialization -----   
 gpioInit.GPIO_Pin = led1|led2|led3|led4;
 gpioInit.GPIO_Mode = GPIO_Mode_Out_PP;
  gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 GPIO_Init(led , &gpioInit);       //initialiazate gpio
 GPIO_SetBits(led , gpioInit.GPIO_Pin); //Set pin
 //GPIO_ResetBits(led , gpioInit.GPIO_Pin); //Reset pin

 // Configure USART1 Tx (PA.09) as alternate push-pull --------
 gpioInit.GPIO_Pin = GPIO_Pin_9;
 gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 gpioInit.GPIO_Mode = GPIO_Mode_AF_PP;
 GPIO_Init(GPIOA, &gpioInit);
 // Configure USART1 Tx (PA.10) as alternate push-pull --------
 gpioInit.GPIO_Pin = GPIO_Pin_10;
 gpioInit.GPIO_Speed = GPIO_Speed_50MHz;
 gpioInit.GPIO_Mode = GPIO_Mode_IN_FLOATING;
 GPIO_Init(GPIOA, &gpioInit);
 //----- NVIC initialization -----
 NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);   // 抢占式优先级别
 NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;//指定中断源
 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;// 指定响应优先级别1
 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
 NVIC_Init(&NVIC_InitStructure);
                
 //----- UART initialization ----
  //0-----串口参数配置------
  USART_InitStructure.USART_BaudRate = 19200;                 //设置波特率为19200
  USART_InitStructure.USART_WordLength = USART_WordLength_8b;  //设置数据位为8位
  USART_InitStructure.USART_StopBits = USART_StopBits_1;       //设置停止位为1位
  USART_InitStructure.USART_Parity = USART_Parity_No;          //无奇偶校验   
  USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; //没有硬件流控
  USART_InitStructure.USART_Mode = USART_Mode_Tx | USART_Mode_Rx;      //send and receive mode
 //0-----------------------
  USART_Init(USART1, &USART_InitStructure); //initialization USART1
 USART_Cmd(USART1 , ENABLE);  //enable USART1 modulation
 USART_ITConfig(USART1, USART_IT_RXNE, ENABLE); //enable USART1 interruption

 //查询方式发送数据
 string = "www.hi.baidu.com/th152210\n";
 GPIO_ResetBits(led , led1|led2); //Reset pin
  putString(string,0); //send string
 GPIO_SetBits(led , led1|led2);   //Set pin
 while(1)
 {
 }
}

STM32文件中的相关代码：

void USART1_IRQHandler(void)
{
if(USART_GetFlagStatus(USART1,USART_IT_RXNE)==SET)
{  
 USART_ClearITPendingBit(USART1,USART_IT_RXNE);//清除中断标志         
 USART_SendData(USART1 , USART_ReceiveData(USART1));
}
}