Get string with Unknown length from serial Port

mo2_star · Feb 27, 2015

hello My friends,

I have A problem in my Project

I have A String
I have to receive it From Serial Port And Use It

First Problem is How Receive it? When it is between 0 to 9 it has 9 Characters,And from 10 to 99 it has 10 Characters,And from 100 to 255 it has 11 Characters

This Strring Starts With * And Ends With #
Example:
*11|11|1#
*11|11|9#
*11|11|54#
*11|11|87#
*11|11|110#
*11|11|180#
*11|11|254#
This Project Is With C Language and I use AVR Codevison.

Problem # 2
How Use The numeric variable From the String After Receiving?
sample : 1,9,54,87,110,180,254
I want To use It for OCR1A Register For PWM.

andre_luis · Feb 27, 2015

You could store all bytes received into a temporary buffer, so that just after detecting of the end-of-stream character '#' you would perform the weighting of each one by a 10th scale factor; something like that ( may contain either syntax or logic errors ):

Code C - [expand]
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bool StoreValue = FALSE ;
if ( ByteReceivedFromUart == '#' )
i=0;
switch ( ByteReceivedFromUart )
{
case : '*' ; i++ ; break ;
case : '1' ; i++ ; break ;
case : '1' ; i++ ; break ;
case : '|' ; i++ ; break ;
case : '1' ; i++ ; break ;
case : '1' ; i++ ; break ;
case : '|' ; i++ ; break ;
default : i=0  StoreValue = TRUE  ; break ;
}
// Store values according sequence of reception 
if ( StoreValue  )
     i=0;
     While ( i =! '#' )   // while not reached end of reception, performs assignent bellow
        Temp[i++] = ByteReceivedFromUart ;  // load each byte received form UART
 
     // Calculate weighted values on inverse order of reception
     j=i ;
     While ( j > 0 )
         Value=(10^i ) * Temp[j-i] ; // note that the last value received is the most significant

Note:
It is assumed that you alredy performed ASCII conversion to decimal

mo2_star · Feb 28, 2015

Code:

while (1)
      {     
            
            z[11]=0x00;
            i=0;
            delay_ms(100);
            while(z[i]!=0x23){   
            i++;
            z[i]=getchar();
            }   
            
            switch (z[8])
            {    
            case '0':z1=0 ;break;
            case '1':z1=1 ;break;
            case '2':z1=2 ;break;
            case '3':z1=3 ;break;
            case '4':z1=4 ;break;
            case '5':z1=5 ;break;
            case '6':z1=6 ;break;
            case '7':z1=7 ;break;
            case '8':z1=8 ;break;
            case '9':z1=9 ;break;
            case 0x23:z1=0 ;break;  
            default :z1=0 ;break;
            } 
            switch (z[9])
            {    
            case '0':z2=0 ;break;
            case '1':z2=1 ;break;
            case '2':z2=2 ;break;
            case '3':z2=3 ;break;
            case '4':z2=4 ;break;
            case '5':z2=5 ;break;
            case '6':z2=6 ;break;
            case '7':z2=7 ;break;
            case '8':z2=8 ;break;
            case '9':z2=9 ;break; 
            case 0x23:z2=0 ;break;  
            default :z2=0 ;break;
            }
            switch (z[10])
            {    
            case '0':z3=0 ;break;
            case '1':z3=1 ;break;
            case '2':z3=2 ;break;
            case '3':z3=3 ;break;
            case '4':z3=4 ;break;
            case '5':z3=5 ;break;
            case '6':z3=6 ;break;
            case '7':z3=7 ;break;
            case '8':z3=8 ;break;
            case '9':z3=9 ;break;   
            case 0x23:z3=0 ;break;  
            default :z3=0 ;break;
            }  
           
            lcd_clear();
            lcd_gotoxy(0,0);
            lcd_puts("ok:"); 
            lcd_gotoxy(1,1);
            lcd_putchar(z[8]); 
            lcd_putchar(z[9]);
            lcd_putchar(z[10]); 
            lcd_puts("  ");
            z1=z1*100;
            z2=z2*10;
            z3=z3*1;
            sum=z2+z1;
            sum=sum+z3;
            lcd_puts("  "); 
            sprintf(str,"%d",sum);
            lcd_puts(str);
            OCR1A=sum;
      } 
}

I do it.
Thanks
Know I have A new Problem
i don't know why happened

When My numeric variable is higher than 99 (100,124,...,255)
It is Ok.
But When numeric variable is lower than 99
it turns to 34#,53#
but my output should be 34,53,...
but it is 340,530,...
In my case I Switch "#" to 0 but it happened.

Get string with Unknown length from serial Port

mo2_star

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andre_luis

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Get string with Unknown length from serial Port

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