AVR Freaks

Hi all,

   Good Day! I have two problems.

Problem 1: I have problem in strlen calculation. I am trying to calculate CRC16 for a FRAME with initial value of CRC = 0xFFFF. In this code if i initialized unsigned char array as global then i am getting correct strlen value. after sending a frame i am getting strlen value as 62. it is giving the value 62 = 4 + 58(frame length). In this if i initialized unsigned char as local then i am getting strlen is 10. I am allocating only 4 byte but how i am getting 10 as strlen?

Frame Format:

*0,0,0,0,1,6,1,2,3,4,5,6,2,1,1,1,B,2,2,1,0.00,00.0,0.00,0#

Problem 2: How to compare crc0 value with crc1 value. crc0 is unsigned int and crc1 is unsigned char array. in the below code 

if(crc0 == crc1) Is this comparison is correct or not.

 Even i tried with pointers.

can you please give me a guidance to get a solution for these two problems.

Code is:

/*****************************************************
This program was produced by the
CodeWizardAVR V2.05.3 Standard
Automatic Program Generator
© Copyright 1998-2011 Pavel Haiduc, HP InfoTech s.r.l.
http://www.hpinfotech.com

Project :
Version :
Date    : 4/10/2015
Author  : Dev6
Company : sass
Comments:


Chip type               : ATmega128
Program type            : Application
AVR Core Clock frequency: 14.745600 MHz
Memory model            : Small
External RAM size       : 0
Data Stack size         : 1024
*****************************************************/

#include <mega128.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <delay.h>

unsigned char rx_rcv=0, rcv_comp=0;
unsigned char uartin_data[256];
unsigned char temp_uartin[26];
unsigned int uartin_length=0;



#ifndef RXB8
#define RXB8 1
#endif

#ifndef TXB8
#define TXB8 0
#endif

#ifndef UPE
#define UPE 2
#endif

#ifndef DOR
#define DOR 3
#endif

#ifndef FE
#define FE 4
#endif

#ifndef UDRE
#define UDRE 5
#endif

#ifndef RXC
#define RXC 7
#endif

#define FRAMING_ERROR (1<<FE)
#define PARITY_ERROR (1<<UPE)
#define DATA_OVERRUN (1<<DOR)
#define DATA_REGISTER_EMPTY (1<<UDRE)
#define RX_COMPLETE (1<<RXC)

// USART0 Receiver buffer
#define RX_BUFFER_SIZE0 256
char rx_buffer0[RX_BUFFER_SIZE0];

#if RX_BUFFER_SIZE0 <= 256
unsigned char rx_wr_index0,rx_rd_index0,rx_counter0;
#else
unsigned int rx_wr_index0,rx_rd_index0,rx_counter0;
#endif

// This flag is set on USART0 Receiver buffer overflow
bit rx_buffer_overflow0;

// USART0 Receiver interrupt service routine
interrupt [USART0_RXC] void usart0_rx_isr(void)
{
    char status,data;
    status=UCSR0A;
    data=UDR0;

    if(data == '*')
    {
        rcv_comp = 0;
        rx_wr_index0 = 0;
        rx_rcv = 1;
        uartin_length = 0;
    }

    if(data == '#')
    {
        rcv_comp = 1;
    }

    if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
    {
       rx_buffer0[rx_wr_index0++]=data;
    #if RX_BUFFER_SIZE0 == 256
       // special case for receiver buffer size=256
       if (++rx_counter0 == 0) rx_buffer_overflow0=1;
    #else
       if (rx_wr_index0 == RX_BUFFER_SIZE0) rx_wr_index0=0;
       if (++rx_counter0 == RX_BUFFER_SIZE0)
       {
          rx_counter0=0;
          rx_buffer_overflow0=1;
       }
    #endif
    }
}

#ifndef _DEBUG_TERMINAL_IO_
// Get a character from the USART0 Receiver buffer
#define _ALTERNATE_GETCHAR_
#pragma used+
char getchar(void)
{
char data;
while (rx_counter0==0);
data=rx_buffer0[rx_rd_index0++];
#if RX_BUFFER_SIZE0 != 256
if (rx_rd_index0 == RX_BUFFER_SIZE0) rx_rd_index0=0;
#endif
#asm("cli")
--rx_counter0;
#asm("sei")
return data;
}
#pragma used-
#endif


unsigned int crc16_update_little_endian(unsigned int crc, unsigned char arr[])
{
    // Least significant bit first (little-endian)
   // x^16+x^15+x^2+1 = 1010 0000 0000 0001 (1) = 0xA001  (CRC 16 POLYNOMIAL REVERSED)

    unsigned int i,j;

    for(j =0; j<26/*strlen(arr)*/; ++j)
    {
        crc ^= arr[j];
        for (i = 0; i < 8; ++i)   // Assuming 8 bits per byte
        {
            if (crc & 0x0001)   // if rightmost (most significant) bit is set
            {
                crc = (crc >> 1) ^ 0xA001;
            }
            else
            {
                crc = (crc >> 1);
            }
        }
        //printf("\nj: %d, \tcrc: %X", j,crc);
    }
    return crc;
}


void uartin_function(void)
{
    unsigned int i=0,j=0,k=0;
    unsigned int crc0 = 0xFFFF;   //0x0000
    unsigned char crc1[4] = {'0','0','0','0'};
    //unsigned char *pcrc = "0000";
    //pcrc = malloc(4);

    //printf("\nstrlen_crc1: %d, \tstrlen_a: %d", strlen(crc1),strlen(a));
//    printf("\nstrlen_crc1: %d", strlen(crc1));

    //uartin_length = rx_wr_index0;

    if(rx_rcv == 1)
    {
        if(rcv_comp == 1)
        {
            strcpy(uartin_data,rx_buffer0);
            puts(uartin_data);

            for(i=1; i<32;)
            {
                temp_uartin[j] = uartin_data[i];
                //printf("\ntemp_uartin[%d]: %c", j,temp_uartin[j]);
                i+=2;
                ++j;
            }
            for(i=41; i<57;)
            {
                temp_uartin[j] = uartin_data[i];
                if((i==41)||(i==44)||(i==47)||(i==49)||(i==51)||(i==56))
                {
                    i+=2;
                }
                else
                {
                    ++i;
                }
            }
            crc0 = crc16_update_little_endian(crc0, temp_uartin);
            //printf("\ncrc0 = %X", crc0);

            for(i=33; i<40;)
            {
                crc1[k] = uartin_data[i];
                //*(pcrc) = uartin_data[i];
                //printf("\ncrc1[%d]: %c", k,crc1[k]);
                i+=2;
                ++k;
                //++pcrc;
            }
            puts(crc1);
            //pcrc=crc1;
            //puts(pcrc);

            if(crc0 == crc1)
            {
                puts("\nTRUE");
                puts(crc1);
            }
            else
            {
                puts("\nFALSE");
                puts(crc1);
            }
        }
        rcv_comp = 0;
    }
    rx_rcv = 0;
}      // end of uartin_function


void main(void)
{
// Declare your local variables here

// Input/Output Ports initialization
// Port A initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTA=0x00;
DDRA=0x00;

// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTB=0x00;
DDRB=0x00;

// Port C initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTC=0x00;
DDRC=0x00;

// Port D initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTD=0x00;
DDRD=0x00;

// Port E initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTE=0x00;
DDRE=0x00;

// Port F initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTF=0x00;
DDRF=0x00;

// Port G initialization
// Func4=In Func3=In Func2=In Func1=In Func0=In
// State4=T State3=T State2=T State1=T State0=T
PORTG=0x00;
DDRG=0x00;

// USART0 initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART0 Receiver: On
// USART0 Transmitter: On
// USART0 Mode: Asynchronous
// USART0 Baud Rate: 9600
UCSR0A=0x00;
UCSR0B=0x98;
UCSR0C=0x06;
UBRR0H=0x00;
UBRR0L=0x5F;

// Global enable interrupts
#asm("sei")

    puts("\nstart");


while (1)
      {
           uartin_function();
           delay_ms(2000);
      }
}