I have an AVR Microcontroller which send data to pc from serial port (rs-232) and get data from serial port (rs-232). also i should say that our AVR Microcontroller is in touch with pc just with 2 pins, [pin 3 (TD=Transmit data) and pin 2 (RD=Receive data)]. for example, Microcontroller send two number (A=1,B=2) to pc from serial port (rs-232) and visual c++ get it and add those number (A+B=3) then sends it to Microcontroller from serial port (rs-232). please give me an example which do this.

 

<p>Sealevel Systems (http://www.sealevel.com) includes code samples on the software CD that ships with all serial products. This C++ code sample shows you how to open a COM port, and send & receive data. In this example, data is sent and read at 460K bps, but standard windows ports are limited to 115K bps.

<p>----- Begin Code Sample -----
<pre>
#include "stdafx.h"
#include
#include
#include
int main(int argc, char* argv[])
{
char INBUFFER[500];
char OUTBUFFER[20];
DWORD bytes_read = 0; // Number of bytes read from port
DWORD bytes_written = 0; // Number of bytes written to the port
HANDLE comport = NULL; // Handle COM port
int bStatus;
DCB comSettings; // Contains various port settings
COMMTIMEOUTS CommTimeouts;
strcpy(&OUTBUFFER[0], "The quick brown fox jumped over the lazy dog. \n\r\0");
// Open COM port
if ((comport =
CreateFile("\\\\.\\COM5", // open com5:
GENERIC_READ | GENERIC_WRITE, // for reading and writing
0, // exclusive access
NULL, // no security attributes
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL)) == INVALID_HANDLE_VALUE)
{
// error processing code goes here
}
// Set timeouts in milliseconds
CommTimeouts.ReadIntervalTimeout = 0;
CommTimeouts.ReadTotalTimeoutMultiplier = 0;
CommTimeouts.ReadTotalTimeoutConstant = 100;
CommTimeouts.WriteTotalTimeoutMultiplier = 0;
CommTimeouts.WriteTotalTimeoutConstant = 100;
bStatus = SetCommTimeouts(comport,&CommTimeouts);
if (bStatus != 0)
{
// error processing code goes here
}
// Set Port parameters.
// Make a call to GetCommState() first in order to fill
// the comSettings structure with all the necessary values.
// Then change the ones you want and call SetCommState().
GetCommState(comport, &comSettings);
comSettings.BaudRate = 460800;
comSettings.StopBits = ONESTOPBIT;
comSettings.ByteSize = 8;
comSettings.Parity = NOPARITY;
comSettings.fParity = FALSE;
bStatus = SetCommState(comport, &comSettings);
if (bStatus == 0)
{
// error processing code goes here
}
while(!kbhit())
{
bStatus = WriteFile(comport, // Handle
&OUTBUFFER, // Outgoing data
48, // Number of bytes to write
&bytes_written, // Number of bytes written
NULL);
if (bStatus != 0)
{
// error processing code here
}
bStatus = ReadFile(comport, // Handle
&INBUFFER, // Incoming data
500, // Number of bytes to read
&bytes_read, // Number of bytes read
NULL);
if (bStatus != 0)
{
// error processing code goes here
}
// code to do something with the data goes here
}
CloseHandle(comport);
return 0;
}
</pre>

 

It is easy to use MSComm control as compared to API.

 

Thanks for commenting.

If it is possible through the MSComm control then how?

Please guide me coz i am doing the same thing.

Kashif

[email protected]

 

Hello,

i tried ur code but using WINAPI. when i execute the application, i am getting read file status = 1 which is fine but when i try to read the INBUFFER data i am not able to get proper data. i written a for loop to read the INBUFFER data

can you please guide me where i am going wrong

Reagrds
Ms. Shrividya
(shri.88vidya [at] rediffmail.com, rnd [at] eecindia.com)

 

SetCommTimeouts() returns 0 on failure

 

The CommTimeouts in this code cause a huge read/write latency.
Changing the values as follows reduced my latency from ~200ms to ~6ms.<pre>
// A ReadIntervalTimeout value of MAXDWORD, combined with zero values for both the ReadTotalTimeoutConstant
// and ReadTotalTimeoutMultiplier members, specifies that the read operation is to return immediately with
// the bytes that have already been received, even if no bytes have been received.

CommTimeouts.ReadIntervalTimeout = MAXDWORD;
CommTimeouts.ReadTotalTimeoutMultiplier = 0;
CommTimeouts.ReadTotalTimeoutConstant = 0;
CommTimeouts.WriteTotalTimeoutMultiplier = 0;
CommTimeouts.WriteTotalTimeoutConstant = 0;</pre>

 

d:\computer programming with applications\cpa\wb\wb\wb1.cpp(1): fatal error C1083: Cannot open include file: 'stdafx.h': No such file or directory
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

i get this error when i run this program
can any one help me