[En-Nut-Discussion] Timing problem with a rs485 line? or something else...

[Ovidiu]

Hello,

 I am trying to make a character (byte) oriented simple protocol over the
serial line using two ethernut 1 boards connected together  with a rs485
line (using the extension port), but I'm having serious problems.

the code must look like this, otherwise it's not working:
        wait(2);                                       //PROBLEM!!!!
        fread(&octet,sizeof(char),1,stream);

(the wait is done by repeating the _delay_ms(10) function from libc, I can't
use NutSleep() cause other proceses will also read/write the serial line)

and I'm trying to read a structure like this:

typedef struct
{
    char cmd;
    char id;
    int val;
} msg485_t;

msg485_t msg;

with the function:
read485(&msg,sizeof(msg485_t),rs485);

I dont know what is happening, maybe is a problem with the buffers or maybe
some echo on the line...

Thank you,
Ovidiu

PS:
1)Can Anyone, pleeeaaasseee help me before I throw my computer through the
window.
2)The rest of the code:

The function that is not working correctly:

void read485(void *buf,int marime,FILE *stream)
{

    char octet;
    char *buffer;
    buffer=buf;
//    printf("\nLength:%i\n",marime);
    for(;;)
    {
    fread(&octet,sizeof(char),1,stream);
    if(octet==_ESCAPE)
    {
//        printf("Escape received\n");
        wait(2);                                       //PROBLEM!!!!
        fread(&octet,sizeof(char),1,stream);
        if(octet==_START)
        {
//            printf("Start received\n");
            int pozitie=0;
            for(pozitie=0;pozitie<marime;pozitie++)
            {
                wait(2);
                fread(&octet,sizeof(char),1,stream);
                wait(2);
//                printf("A char came for pozition:%i and the char
is:%c\n",pozitie,octet);
                if(octet==_ESCAPE)
                {
                    printf("Am primit un caracter escape!\n");
                    fread(&octet,sizeof(char),1,stream);
                    wait(2);
                    if(octet==_START)
                    {
                        pozitie=0;//when an error occurs (a start in the
midle of the message), resincronize on the current start
                    }
                    else if(octet==_ESCAPE)
                    {
                        buffer[pozitie]=_ESCAPE;
                    }
                    else
                    {
                        break;
                    }
                }
                buffer[pozitie]=octet;
//                printf("Buffer at pozitie=%i is:%s\n",pozitie,buffer);
            }
        if(pozitie==marime) break;
        }
    }
    }
}

The function I used to send the data:

void write485(void *m_orig,int marime,FILE* stream)
{
    char m_final[20];
    char *m_original;
    m_original=m_orig;
    printf("Original message:%s length:%i\n",m_original,marime);//debugging
only
    m_final[0]=_ESCAPE;
    m_final[1]=_START;
    int i=0;
    int pozitie=2;
    for(i=0;i<marime;i++)
    {
        printf("i=%i pozitie=%i
m_original[i]=%c\n",i,pozitie,m_original[i]);//debug only
        if(m_original[i]==_ESCAPE)
        {
            printf("Found an escape char!");//debug only
            m_final[pozitie]=_ESCAPE;
            pozitie++;
            m_final[pozitie]=_ESCAPE;
            pozitie++;
        }
        else
        {
            m_final[pozitie]=m_original[i];
            pozitie++;
        }
    }

    printf("Final message:%s\n",m_final);
    fwrite(m_final,pozitie,1,stream);//the fwrite itself
    fflush(stream);
}


void wait(int ms)
{
    int i;
    for(i=0;i<ms;i++)
    {
        _delay_ms(10);
    }
}