com.c

RS232串口通信协议

// RS-232 example
// Compiles with Microsoft Visual C++ 5.0/6.0
// (c) fpga4fun.com KNJN LLC - 2003, 2004, 2005, 2006

#include <windows.h>
#include <stdio.h>
#include <conio.h>

HANDLE hCom;

void OpenCom()
{
	DCB dcb;
	COMMTIMEOUTS ct;

	hCom = CreateFile("COM1:", GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
	if(hCom==INVALID_HANDLE_VALUE) exit(1);
	if(!SetupComm(hCom, 4096, 4096)) exit(1);

	if(!GetCommState(hCom, &dcb)) exit(1);
	dcb.BaudRate = 115200;
	((DWORD*)(&dcb))[2] = 0x1001;  // set port properties for TXDI + no flow-control
	dcb.ByteSize = 8;
	dcb.Parity = NOPARITY;
	dcb.StopBits = 2;
	if(!SetCommState(hCom, &dcb)) exit(1);

	// set the timeouts to 0
	ct.ReadIntervalTimeout = MAXDWORD;
	ct.ReadTotalTimeoutMultiplier = 0;
	ct.ReadTotalTimeoutConstant = 0;
	ct.WriteTotalTimeoutMultiplier = 0;
	ct.WriteTotalTimeoutConstant = 0;
	if(!SetCommTimeouts(hCom, &ct)) exit(1);
}

void CloseCom()
{
	CloseHandle(hCom);
}

DWORD WriteCom(char* buf, int len)
{
	DWORD nSend;
	if(!WriteFile(hCom, buf, len, &nSend, NULL)) exit(1);

	return nSend;
} 

void WriteComChar(char b)
{
	WriteCom(&b, 1);
}

int ReadCom(char *buf, int len)
{
	DWORD nRec;
	if(!ReadFile(hCom, buf, len, &nRec, NULL)) exit(1);

	return (int)nRec;
}

char ReadComChar()
{
	DWORD nRec;
	char c;
	if(!ReadFile(hCom, &c, 1, &nRec, NULL)) exit(1);

	return nRec ? c : 0;
}

void main()
{
	char c, s[256];
	int len;

	OpenCom();

	// sending data
	WriteComChar(0x41);		WriteComChar(0x42);		WriteComChar(0x43);	
	WriteCom("ABCDE", 5);
	Sleep(3);

	// receiving data
	len = ReadCom(s, sizeof(s)-1);	s[len] = 0;	printf("%s", s);
	while(c=ReadComChar()) printf("%c", c);

	CloseCom();
	printf("Press a key to exit");	getch();
}