一、串口助手

串口助手主要是帮助读取串口数据，使其在上位机上显示出来。下面的代码可以帮助我们理解串口通信的过程。

二、代码

#define _CRT_SECURE_NO_WARNINGS
#include <windows.h>
#include <stdio.h>
#include <unistd.h> 
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>

HANDLE hCom; // 句柄，用于初始化串口

//发送数据进程 
DWORD WINAPI ThreadWrite(LPVOID lpParameter)
{
   printf("This is the write thread!\n"); 
   char outputData[100] = { 0x00 }; // 输出数据缓存

   if (hCom == INVALID_HANDLE_VALUE)
   {
       puts("打开串口失败");
       return 0;
   }

   DWORD strLength = 0;
   while (1)
   { 
       for (int i = 0; i < 100; i++)
       {
           outputData[i] = 0;
       }
       fgets(outputData, 100, stdin); // 从控制台输入字符串
       strLength = strlen(outputData);
       printf("发送了%d个字节\r\n", strLength); // 打印字符串长度
       WriteFile(hCom, outputData, strLength, &strLength, NULL); // 串口发送字符串
       fflush(stdout);
       PurgeComm(hCom, PURGE_TXCLEAR | PURGE_RXCLEAR); // 清空缓冲区
       Sleep(100);
   }
   return 0;
}

//读取数据进程 
DWORD WINAPI ThreadRead(LPVOID lpParameter)
{
   printf("This is the read thread!\n"); 
       // INVALID_HANDLE_VALUE表示出错，会设置GetLastError
   if (hCom == INVALID_HANDLE_VALUE)   
   {
           puts("打开串口失败");
       return 0;
   }
   char getputData[100] = { 0x00 }; // 输入数据缓存
   // 利用错误信息来获取进入串口缓冲区数据的字节数
   DWORD dwErrors; // 错误信息
   COMSTAT Rcs; // COMSTAT结构通信设备的当前信息
   int Len = 0;
   DWORD length = 100; //用来接收读取的字节数
   char path[] = "./test.txt";
   int fd = 0,n = 1;
   fd = open(path,O_RDWR|O_CREAT);
   //write(fd,"H,class\n",8);
   while (1)
   {
       for (int i = 0; i < 100; i++)
       {
           getputData[i] = 0;
       }
       ClearCommError(hCom, &dwErrors, &Rcs); // 获取读缓冲区数据长度
       Len = Rcs.cbInQue;
       ReadFile(hCom, getputData, Len, &length, NULL);  // 获取字符串
       PurgeComm(hCom, PURGE_TXCLEAR | PURGE_RXCLEAR);  // 清空缓冲区
       if (Len > 0)
       {
           //printf("接收的数据为：%s\r\n", getputData);
           //sleep(1);
           printf(getputData);
           //strcat(getputData,",1");
           //strcat(getputData,"\n");
           sleep(1);
           lseek(fd,0,SEEK_END);
           int ret = write(fd,&getputData,strlen(getputData));
           //printf("fd = %d,ret = %d\n",fd,ret);
           fflush(stdout);
       }
       //Sleep(2);
   }
   return 0;
}

int main()
{
   // 初始化串口
   TCHAR *com_name = (TCHAR *)malloc(10 * sizeof(TCHAR));
   do
   {
       printf("请输入需要打开的串口号（示例：COM2）:");
       scanf("%s",com_name);
       getchar();
       hCom = CreateFile(com_name, GENERIC_READ | GENERIC_WRITE, 
                       0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
       if (hCom == INVALID_HANDLE_VALUE)
           printf("串口号不存在，请重新输入！\n");
       else
           break;
   } while (1);
   free(com_name);

   // 获取和设置串口参数
   DCB myDCB;
   myDCB.BaudRate = 115200;       // 波特率
   myDCB.Parity = NOPARITY;     // 校验位
   myDCB.ByteSize = 8;          // 数据位
   myDCB.StopBits = ONESTOPBIT; // 停止位
   SetCommState(hCom, &myDCB);  // 设置串口参数
   printf("baud rate is %d\n", (int)myDCB.BaudRate);

   // 线程创建
   HANDLE HRead, HWrite;
   //HWrite = CreateThread(NULL, 0, ThreadWrite, NULL, 0, NULL);
   HRead = CreateThread(NULL, 0, ThreadRead, NULL, 0, NULL);

   while (1);

   CloseHandle(HRead);
   //CloseHandle(HWrite);
       CloseHandle(hCom);
   return 0;
}