c - Error getting data from GSM SIM900

I am interfacing with GSM SIM900. I wrote a program so that I can read the SMS in SIM900. I have made a function to transmit and receive. Whenever msg comes, GSM responds with +CMT along with slot number.I am trying to extract that slot number which is in digits, but I am getting garbage values

Here is the code:

while(1)
{
    if (serial_Rx() != NULL) // SOMETHING PRESENT TO BE READ
    {
        serial_Tx("done"); // print done 
        PORTC = 0x01; // turn on led

        for (int i=0;i<=14;i++)
        {
            data[i] = serial_Rx(); //storing received in data

            if(isdigit(data[i]))
            {
                serial_Tx("enter");
                PORTC = 0x02;
                data1[i] = data[i];
                serial_Tx(data1[i]);

            }
        }               
    }
}

Transmit and receive funstions:

void serial_Tx(char *str)
{
    for (unsigned int i=0;str[i]!=0;i++)
    {

        UDR=str[i];
        while(!(UCSRA&(1<    }
}

char serial_Rx()
{
    //Wait untill a data is available
    while(!(UCSRA & (1<    {

         //Do nothing
    }

    //Now USART has got data from host and is available is buffer
    return UDR;
}

void uart_put(char data)
{
    UDR=data;

    while(!(UCSRA&(1<}

Hyperterminal:

Answer

In your code the following function call is wrong:

serial_Tx(data1[i]);

Because data1[i] has a type of char but void serial_Tx(char *str) expects a char*, this function is for sending strings, not single characters. This way it causes runtime error, hence you won't get the expected output.

Though, it won't generate a compilation error, but the compiler will give a warning like this:

It is recommended to check and fix these warnings, because as you could see they could cause troubles in runtime.

So, replace the function above with the void uart_put(char data) function, like:

uart_put(data[i]);

and it will work.