Thread: USB to Serial (to and fro) communication using C language

Hi eveybuddy,
This is the 1st time am posting my query. I am in need of help. Any help is appreciated.


As i agree that i have given my prob as long story. But am sorry i am not getting how to make it short and my intention is to give complete information regarding my prob.


Problem :
I have to communicate between two laptops using USB-to-Serial adapter. I have written 2 programs one for sending and another for receiving. Programs were written in both C and C# programming languages.


Using C language :
I am able to successfully communicate using C-Programs mentioned below. But the problem is speed. It takes around 1 hour(60min) for just to pass 150MB. Anyone plz help me in improving the performance of this programs or you may suggest me other approaches which is robust and give high performance. I also mention some comments along with programs for self understanding.


Sender File on laptop with serial port :

Code:

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


#define COM1       0
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0


#define SETTINGS ( 0xE0 | 0x03 | 0x00 | 0x00)


int main(void)
{
   int in, out, status, DONE = FALSE,i=0;
   char c;
   FILE *fp,*fp1;
   unsigned long count = 0,shiftcount = 0;


   clrscr();


   fp = fopen("C:/TC/pic.jpg","rb"); //opened for reading actual content
   fp1 = fopen("C:/TC/pic.jpg","rb"); //opened for reading the size of file


   fseek(fp1,0L,2);
   count = ftell(fp1) + 1; // file size


   bioscom(0, SETTINGS, COM1); // initializing the port


   printf("No. of Characters = %lu\n",count);


// since bioscom function can send or receive only 8bits at a time, am sending file size in
    4 rounds so that we can send at max of 4GB file.


   bioscom(1,count,COM1); // sneding 1st lower 8bits 


   bioscom(1,count>>8,COM1); // sending 2nd set of lower 8bits


   bioscom(1,count>>16,COM1); // sending 3rd set of lower 8bits


   bioscom(1,count>>24,COM1); // sending upper 8 bits


   cprintf("... BIOSCOM [ESC] to exit ...\n");
   while (!DONE)
   {
      status = bioscom(3, 0, COM1);// get the status of port
      //printf("%d",status);
      if (status & DATA_READY) //checks if data is ready
      {
        out = bioscom(2, 0, COM1); // receives the ack
        if(!feof(fp))
        {
            c = fgetc(fp); //read character by character from file
            bioscom(1,c,COM1);//send character to receiver
            putch(c);//display
        }
     }


//to interrupt
     if (kbhit())
     {
        if ((in = getch()) == '\x1B')
           DONE = TRUE;
     }
   }
   fclose(fp);
   return 0;
}

Receiving file on laptop with USB port :

Code:

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


#define COM4       3
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0


#define SETTINGS ( 0xE0 | 0x03 | 0x00 | 0x00)


int main(void)
{
   int in, out, status;
   char c;
   FILE *fp;
   unsigned long shiftcount1=0,shiftcount2=0,shiftcount3=0,shiftcount4=0;
   unsigned long count = 0, DONE = 1;


   clrscr();


   fp = fopen("C:/TC/pic1.jpg","wb");// file opened for writing


   bioscom(0, SETTINGS, COM4);//initialize tyhe port
   cprintf("... BIOSCOM [ESC] to exit ...\n");
//receives all the 32 bits of file size sent from sender
   shiftcount1 = bioscom(2,0,COM4);
   shiftcount2 = bioscom(2,0,COM4);
   shiftcount3 = bioscom(2,0,COM4);
   shiftcount4 = bioscom(2,0,COM4);


//send an ack
   bioscom(1,'x',COM4);


   count = shiftcount1 | (shiftcount2<<8) | (shiftcount3<<16) | (shiftcount4<<24);


   printf("shift4 = %lu\tshift3 = %lu\tshift2 = %lu\tshift1 = %lu\n",shiftcount4,shiftcount3,shiftcount2,shiftcount1);
   printf("File Size = %lu\n",count);


//loop till the size of the file
   while (DONE < count)
   {
      status = bioscom(3, 0, COM4);// check the status
     // printf("%d",status);
      if (status & DATA_READY)//check for data ready at the port
      {
        out = bioscom(2, 0, COM4);//receive the data
        DONE++;
        fputc(out,fp);
        putch(out);
        bioscom(1,'x',COM4);//send an ack
      }




     if (kbhit())
     {
        if ((in = getch()) == '\x1B')
        break;
     }
   }
   fclose(fp);
   return 0;
}

Sender file on laptop with USB port:

Code:

#include <stdio.h>
#include <bios.h>
#include <conio.h>
#include<dos.h>
#include<stdlib.h>
#include<time.h>


#define RTS 0x02
#define COM1       0
#define    COM4       3
#define CURRCOM      COM4
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0


#define SETTINGS ( 0xE0 | 0x03 | 0x00 | 0x00)


int main(void)
{
   int in, out, status, DONE = FALSE,nextfile = 1;
   char c;
   FILE *fp,*fp1;
   unsigned long count = 0,shiftcount = 0;
   clock_t start,end;


   start = clock();


   clrscr();


   fp = fopen("C:/TC/pic.jpg","rb");
   fp1 = fopen("C:/TC/pic.jpg","rb");


   fseek(fp1,0L,2);
   count = ftell(fp1) + 1;


   bioscom(0, SETTINGS, CURRCOM);


  /*  while(!feof(fp1))
    {
    c = fgetc(fp1);
    count++;
    } */




   printf("No. of Cheracters = %lu\n",count);




    bioscom(1,count,CURRCOM);


    bioscom(1,count>>8,CURRCOM);


    bioscom(1,count>>16,CURRCOM);


    bioscom(1,count>>24,CURRCOM);


   cprintf("\n... BIOSCOM [ESC] to exit ...\n");
   while (!DONE)
   {
      status = bioscom(3, 0, CURRCOM);
      if (status & DATA_READY)
      {
        out = bioscom(2,0,CURRCOM);


        if(!feof(fp))
        {
            c = fgetc(fp);
            bioscom(1,c,CURRCOM);
            putch(c);
        }
      }


     if (kbhit())
     {
        if ((in = getch()) == '\x1B')
           DONE = TRUE;
     }
   }
   fclose(fp);


   end = clock();
   printf("\nTotal time = %d\n",(end - start)/CLK_TCK);


   return 0;
}

Receiver file on laptop with serial port :

Code:

#include <stdio.h>
#include <bios.h>
#include <conio.h>
#include<time.h>


#define COM1       0
#define DATA_READY 0x100
#define TRUE       1
#define FALSE      0


#define SETTINGS ( 0xE0 | 0x03 | 0x00 | 0x00)


int main(void)
{
   int in, out, status;
   char c;
   FILE *fp;
   int y = 0,esc;
   unsigned long count=0,shiftcount1 = 0,shiftcount2 = 0,shiftcount3 = 0,shiftcount4 = 0, DONE = 1;


   clock_t start,end;


   start = clock();


   clrscr();


   fp = fopen("C:/TC/pic1.jpg","wb");


   bioscom(0, SETTINGS, COM1);
   cprintf("... BIOSCOM [ESC] to exit ...\n");


   shiftcount1 = bioscom(2,0,COM1);
   shiftcount2 = bioscom(2,0,COM1);
   shiftcount3 = bioscom(2,0,COM1);
   shiftcount4 = bioscom(2,0,COM1);


   bioscom(1,'x',COM1);


   count = shiftcount1 | (shiftcount2<<8) | (shiftcount3<<16) | (shiftcount4<<24);


   printf("shift4 = %lu\tshift3 = %lu\tshift2 = %lu\t shift1 = %lu\n",shiftcount4,shiftcount3,shiftcount2,shiftcount1);
   printf("file size = %lu\n",count);


   while (DONE < count)
   {
      status = bioscom(3, 0, COM1);
      //printf("%d",status);
      if (status & DATA_READY)
      {
        out = bioscom(2, 0, COM1);
        DONE++;
        fputc(out,fp);
        putch(out);
        bioscom(1,'x',COM1);
      }




     if (kbhit())
     {
        if ((in = getch()) == '\x1B')
           break;
     }
   }
   fclose(fp);


   end = clock();
   printf("\nTotal time = %f\n",(end - start)/CLK_TCK);


   return 0;
}

The above 4 programs behaves as, sender send a character and receives an ack for every character. I have followed this approach, bcoz other approaches were not working fine (in the sense the complete data is not sent, the amount of data sent is not judgeable, bcoz it will different every tym). when i used this approach it worked fine.



Please help me.


Thanks in advance.
[/code]

Same question in C# as well.
USB to Serial (to and fro) communication using C# language

Originally Posted by chetanraj

3. Am using CONIO.H and DOS.H, is just because, the program that is written for communication must be compatible to DOS environment. It is a prime requisite that, the programs will be run in the DOS environment.

I tried to search other libraries and function, but I am not succeeded in searching. Could any one please suggest some libraries or functions that works in DOS environment and uses Serial port(RS-232) as a basic communication interface for transmitting and receiving data.

You could try DJGPP, which is basically like MinGW for DOS. It is old, but probably newer than whatever DOS stuff you are trying now. DJGPP has support for termios.h which lets you use similar methods as Linux to access the serial port

Documentation of DJGPP termios

DJGPP C Library Reference

Example of using termios

linux - how to open, read, and write from serial port in C - Stack Overflow

Obviously you'll have to make adjustments for the environment, for example in DJGPP I doubt the serial port is called /dev/ttyUSB1