使用window API开发一个具有字符串收发功能的串口助手
开发环境
- Visual Studio 2015
串口设备相关的API
-
CreateFile
参数详情见：https://docs.microsoft.com/en-us/windows/win32/api/fileapi/nf-fileapi-createfilea?redirectedfrom=MSDN -
SetCommState
参数详情见：https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setcommstate?redirectedfrom=MSDN -
GetCommState
参数详情见：https://docs.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getcommstate?redirectedfrom=MSDN -
ReadFile
参数详情见：https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee489594(v=winembedded.80)?redirectedfrom=MSDN -
WriteFile
参数详情见：https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee490774(v=winembedded.80)?redirectedfrom=MSDN -
PurgeComm
参数详情见：https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee488020(v=winembedded.80)?redirectedfrom=MSDN -
CloseHandle
参数详情见：https://docs.microsoft.com/en-us/previous-versions/windows/embedded/ee490442(v=winembedded.80)?redirectedfrom=MSDN
// 函数原型
HANDLE WINAPI CreateFile(
_In_ LPCTSTR lpFileName,
_In_ DWORD dwDesiredAccess,
_In_ DWORD dwShareMode,
_In_opt_ LPSECURITY_ATTRIBUTES lpSecurityAttributes,
_In_ DWORD dwCreationDisposition,
_In_ DWORD dwFlagsAndAttributes,
_In_opt_ HANDLE hTemplateFile
);
BOOL WINAPI SetCommState(
_In_ HANDLE hFile,
_In_ LPDCB lpDCB
);
BOOL WINAPI GetCommState(
_In_ HANDLE hFile,
_Inout_ LPDCB lpDCB
);
BOOL ReadFile(
HANDLE hFile,
LPVOID lpBuffer,
DWORD nNumberOfBytesToRead,
LPDWORD lpNumberOfBytesRead,
LPOVERLAPPED lpOverlapped
);
BOOL WriteFile(
HANDLE hFile,
LPCVOID lpBuffer,
DWORD nNumberOfBytesToWrite,
LPDWORD lpNumberOfBytesWritten,
LPOVERLAPPED lpOverlapped
);
BOOL PurgeComm(
HANDLE hFile,
DWORD dwFlags
);
BOOL CloseHandle(
HANDLE hObject
);
步骤
- 创建一个设备句柄
- 创建一个设备文件
- 配置串口参数
- 创建读写线程
- 对设备文件进行读写
- 退出线程后关闭设备文件
实现代码
#define _CRT_SECURE_NO_WARNINGS
#include <windows.h>
#include <stdio.h>
HANDLE hCom; // 句柄，用于初始化串口
DWORD WINAPI ThreadWrite(LPVOID lpParameter)
{
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;
}
DWORD WINAPI ThreadRead(LPVOID lpParameter)
{
// 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
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);
fflush(stdout);
}
Sleep(100);
}
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;
}
收发测试图
- 备注（左边为自己开发的串口软件，右边为正点原子团队开发的XCOM V2.0串口上位机软件）
