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用51单片机的串口读写优盘（U盘）的C语言源码

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 一、简介

　　点评：此文来源于网络，不过仔细研读后发现，这并不是真正意义上的用单片机直接读写优盘的例子，我刚开始看到这个标题也觉得纳闷，我们都知道要读写优盘，必须要单片机系统做成主机模式，由于主机端协议和代码远比设备端复杂，最好在嵌入式系统上跑OS来实现，51单片机由于资源和速度限制，可能做不了这样的事，果不其然，作者其实是用了一块嵌入式模块（基于ARM的嵌入式系统）实现主机功能，再用51与此系统通过串口来通信来实现读写优盘的目的。

　　文章原文：

　　目前，基于USB接口的移动存储设备已经被广泛使用，尤其是采用USB-FLASH技术的U盘产品几乎完全取代了软盘。

　　U盘的使用通常是作为计算机的外部存储设备，能否脱离计算机直接向U盘读写数据呢？答案是肯定的。嵌入式U盘读写模块提供了通过串口读写U盘的简单途径，由此结合单片机的串口就可以实现U盘的文件读写。

　　嵌入式U盘读写模块可以嵌入用户的数据采集系统中，从而实现数据的海量存储。在工控领域，军工产品、石油、交通、水文等野外数据采集系统中可以广泛使用。

二、源码

 

  1. /*                                 C51读写优盘程序 
  2. /*                                                                
  3. /************************************************************************************************ 
  4. * 
  5. *  U盘文件读写模块 以字节为单位进行U盘文件读写。10条精简命令完成所有读写过程 
  6. *  MCS-51单片机C语言示例程序  
  7. *  硬件连接方式: 4线制串口（电源，地，输入，输出）  
  8. */ 
  9. #include <REG51RD2.h> 
  10. #include <stdio.h> 
  11. #define uchar unsigned char 
  12. #define uint unsigned int 
  13. //检测u盘命令 
  14. uchar code Detect[66]={0xaa,0xbb, 
  15.                        0x01,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  16.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  17.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  18.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20};   
  19. //建立TEST.TXT文件命令 
  20. uchar code Create[66]={0xaa,0xbb, 
  21.                        0x07,0x54,0x45,0x53,0x54,0x20,0x20,0x20,0x20,0x54,0x58,0x54,0x20,0x00,0x00,0x00, 
  22.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x63,0x4F,0xFD,0x32,0x00,0x00,0x00,0x00,0x00, 
  23.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 
  24.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}; 
  25. //打开文件命令 
  26. uchar code  Open[66] ={0xaa,0xbb, 
  27.                        0x06,0x54,0x45,0x53,0x54,0x20,0x20,0x20,0x20,0x54,0x58,0x54,0x00,0x00,0x00,0x00, 
  28.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 
  29.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 
  30.                        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}; 
  31. //写文件命令  
  32. uchar code  Write[66]={0xaa,0xbb, 
  33.                        0x09,0x00,74,0x01,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  34.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  35.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  36.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20}; 
  37. //读文件命令 
  38. uchar code  Read[66]={0xaa,0xbb, 
  39.                       0x08,0x08,0x00,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  40.                       0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  41.                       0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  42.                       0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20}; 
  43. //设置文件指针命令 
  44. uchar code SetFilePointer[66]=           
  45.                       {0xaa,0xbb, 
  46.                        0x15,0x00,74,0x01,0x00,0x00,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  47.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  48.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20, 
  49.                        0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20,0x20}; 
  50. //数据1 
  51. uchar code  Date1[66]={0x30,0x31, 
  52.                        0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32, 
  53.                        0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33, 
  54.                        0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33,0x34, 
  55.                        0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33,0x0d,0x0a}; 
  56. //数据2 
  57. uchar code  Date2[66]={0x30,0x31, 
  58.                        0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32, 
  59.                        0x33,0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33, 
  60.                        0x34,0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33,0x34, 
  61.                        0x35,0x36,0x37,0x38,0x39,0x61,0x62,0x63,0x64,0x65,0x30,0x31,0x32,0x33,0x34,0x35}; 
  62. uchar data num; 
  63. void delay_xms(unsigned int);               //延时函数 
  64. void init_com(void);                        //初始化串口函数 
  65. void test(void);                            //系统测试函数 
  66. void Send_Data(uchar Serial_data);          //发送一个字节函数 
  67. void TXD_Int(uchar *s);                     //发送数据函数 
  68. bit Receive_Data(uchar,uint );              //接收数据函数 
  69. uchar Receive_One(void);                    //接收一个字节函数           
  70. void main() 
  71. { 
  72.     int i,j; 
  73.     SP = 0x60;                              //设置堆栈指针 
  74.     P3 = 0xff; 
  75.     init_com();                             //初始化串口 
  76.     test();                                 //系统测试并延时 
  77.  
  78. det:                                        //检测U盘 
  79.     TXD_Int(Detect); 
  80.  
  81.     if(Receive_Data(0x04,0)==0)         //命令是否成功执行，是则继续执行 
  82.     {                                       //否则重新执行 
  83.         delay_xms(1000); 
  84.         goto det; 
  85.     } 
  86.  
  87.     num=0x41; 
  88. for(j=0;j<20;j++) 
  89. {    
  90.         delay_xms(50); 
  91. crt:                                        //建立文件 
  92.     TXD_Int(Create); 
  93.     if(Receive_Data(0x0a,0)==0)             //命令是否成功执行，是则继续执行 
  94.     {                                       //否则重新执行 
  95.         delay_xms(1000); 
  96.         goto crt; 
  97.     } 
  98.      
  99.  
  100.     delay_xms(100); 
  101. wrt:                                        //写文件 
  102.     TXD_Int(Write); 
  103.     for(i=0;i<5;i++) 
  104.         TXD_Int(Date1); 
  105.      
  106.     if(Receive_Data(0x0c,0)==0)             //命令是否成功执行，是则继续执行 
  107.     {                                       //否则重新执行 
  108.         delay_xms(1000); 
  109.         goto wrt; 
  110.     } 
  111.  
  112.     num++; 
  113. } 
  114.  
  115.     delay_xms(500); 
  116. op:                                         //打开文件 
  117.     TXD_Int(Open); 
  118.     if(Receive_Data(0x0d,0)==0)             //命令是否成功执行，是则继续执行 
  119.     {                                       //否则重新执行 
  120.         delay_xms(1000); 
  121.         goto op; 
  122.     } 
  123. /* 
  124.     delay_xms(500); 
  125.                                             //读文件 
  126.     TXD_Int(Read); 
  127.  
  128.     if(Receive_Data(0x0b,8)==0)             //命令是否成功执行，是则继续执行 
  129.     {                                       //否则重新执行 
  130.         delay_xms(1000); 
  131.         goto op; 
  132.     } 
  133. */ 
  134. /* 
  135.     delay_xms(500); 
  136.                                             //删除文件 
  137. del:TXD_Int(Remove); 
  138.  
  139.     if(Receive_Data(0x21,0)==0)             //命令是否成功执行，是则继续执行 
  140.     {                                       //否则重新执行 
  141.         delay_xms(1000); 
  142.         goto del; 
  143.     } 
  144. */ 
  145.  
  146. sfp: 
  147.     TXD_Int(SetFilePointer);                //移动文件指针 
  148.  
  149.     if(Receive_Data(0x25,0)==0)             //命令是否成功执行，是则继续执行 
  150.     {                                       //否则重新执行 
  151.         delay_xms(1000); 
  152.         goto sfp; 
  153.     } 
  154.     delay_xms(500); 
  155.  
  156. wrt2:                                       //二次写文件 
  157.     TXD_Int(Write); 
  158.     for(i=0;i<5;i++) 
  159.         TXD_Int(Date2); 
  160.      
  161.     if(Receive_Data(0x0c,0)==0)             //命令是否成功执行，是则继续执行 
  162.     {                                       //否则重新执行 
  163.         delay_xms(1000); 
  164.         goto wrt2; 
  165.     } 
  166.  
  167.     P0=0; 
  168.     while(1);                               //循环等待 
  169. } 
  170. /******************************************************************** 
  171.                 CoM口波特率初始化函数  
  172. 原型：init_com();  
  173. 功能：初始化com口 
  174. 入口参数：无  
  175. 出口参数：无  
  176. ********************************************************************/  
  177. void init_com( ) 
  178. { 
  179.          
  180.     TMOD = 0x20;                        //计数1工作在方式2 
  181.     TH1 = 0xfa;                         //晶振频率11.0592mhz，9600时为FAH 
  182.     TH1 = 0xfa;                         //19200时为FDH,57600为FFH 
  183.     PCON = 0x80;                        //SMOD为1 
  184.     SCON = 0x40;                        //串行口工作在方式一  
  185.     TI=1; 
  186.     TR1 = 1;                            //启动计数 
  187.  
  188.  
  189. } 
  190. /******************************************************************** 
  191.                          测试系统 
  192. 功能：使发光二极管闪烁 
  193. 入口参数：无 
  194. 出口参数: 无 
  195. ********************************************************************/ 
  196. void test( ) 
  197. { 
  198.     int a=0; 
  199.     P0 = 0xff;                          //P3口初始化，使发光二极管熄灭    
  200.     while(a<10) 
  201.     {    
  202.         P0 = ~P0;                       //P3.3取反 
  203.         delay_xms(500);                 //延时0.5秒 
  204.         a++; 
  205.     } 
  206.     P3 = 0xff; 
  207. } 
  208.  
  209. /******************************************************************** 
  210.                         延时函数 
  211. 功能：共延时1ms乘以delay_time 
  212. 入口参数：延时delay_time ms 
  213. 出口参数：无 
  214. ********************************************************************/ 
  215. void delay_xms(unsigned int delay_time) 
  216. { 
  217.     unsigned int i,j; 
  218.  
  219.     for(i = 0; i < delay_time; i++) 
  220.     { 
  221.         for(j = 0; j < 250; j++);  
  222.     } 
  223. } 
  224. /******************************************************************** 
  225.                        发送一帧数据函数 
  226. 功能：发送一帧数据 
  227. 入口参数：命令帧首地址，数据个数 
  228. 出口参数：无 
  229. ********************************************************************/ 
  230. void TXD_Int(uchar *s) 
  231. { 
  232.          char i;          
  233.          TI = 0;          
  234.          for(i=0; i<66; i++)           //发送64个参数   
  235.          { 
  236.             if(i==7) 
  237.                 Send_Data(num);  
  238.             else 
  239.                Send_Data(*(s+i));  
  240.          } 
  241.          RI = 0; 
  242.          TI = 0;                      //一帧发送完毕 
  243.  
  244. } 
  245. /******************************************************************** 
  246.                       串口发送一个字节 
  247. 功能：发送一个字节数据 
  248. 入口参数：发送数据 
  249. 出口参数：无 
  250. ********************************************************************/ 
  251. void Send_Data(uchar Serial_data) 
  252. { 
  253.     SBUF = Serial_data;             //发送一个字节 
  254.     while(!TI);                     //等待发送 
  255.     TI = 0;                          
  256. } 
  257. /******************************************************************** 
  258.                          接收应答信号和数据函数 
  259. 功能：接收一个字节通讯 
  260. 入口参数：无 
  261. 出口参数：返回接收值 
  262. ********************************************************************/ 
  263. bit Receive_Data(uchar  rxd,uint num) 
  264. { 
  265.     int i; 
  266.     REN = 1;                        //接收位打开 
  267.     P3_3 = 1; 
  268.     P3_5 = 1; 
  269.     if(Receive_One()== rxd)         //接收的是否是应答码 
  270.     { 
  271.         if(Receive_One() == 0x01)   //是应答码，是否是成功执行 
  272.         { 
  273.          
  274.             for(i=0;i<62;i++)       //成功执行，接收62个保留位 
  275.             { 
  276.                 Receive_One(); 
  277.             } 
  278.             P3_3 = 0;               //指示灯亮 
  279.             P3_5 = 0; 
  280.             if(num!=0)              //是否有数据，有则跳接收部分 
  281.                 goto rev; 
  282.             else return(1);         //无，返回1 
  283.          } 
  284.          else                       //未成功执行 
  285.          { 
  286.             for(i=0;i<62;i++)       //接收62个保留位 
  287.             { 
  288.                 Receive_One(); 
  289.             } 
  290.             P3_3 = 1; 
  291.             P3_5 = 0; 
  292.             return(0);              //返回0 
  293.           } 
  294.     } 
  295.     else                            //收到的不是应答码 
  296.     { 
  297.         for(i=0;i<63;i++)           //接收剩下的63个字节 
  298.         { 
  299.             Receive_One(); 
  300.         } 
  301.         P3_3 = 1; 
  302.         P3_5 = 0; 
  303.         return(0);                  //返回0 
  304.      } 
  305.  
  306. rev: 
  307.     if(num>0)                       //应答信号后有数据 
  308.     { 
  309.         for(i=0;i<num;i++)          //接收数据 
  310.             Receive_One(); 
  311.     } 
  312.     REN = 0;                        //关闭接收位 
  313.     return(1);                      //返回1 
  314. } 
  315. /******************************************************************** 
  316.                          接收一个字节通讯函数 
  317. 功能：接收一个字节通讯 
  318. 入口参数：无 
  319. 出口参数：返回接收值 
  320. ********************************************************************/ 
  321. uchar Receive_One(void) 
  322. { 
  323.     while(!RI) 
  324.     { 
  325.         P0=0x00;                    //等待接收 
  326.      } 
  327.      P0=0xff; 
  328.     RI = 0; 
  329.     return(SBUF);               //将接收数据返回 
  330. } 
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