How to send string in serial communication in AVR-C

Question

So as the title states, instead of sending a byte of information at a time, I would like to be able to send a whole string. What I tried to do was that I tried to put the user input in an array and get each element of that array to be transmitted. However I was only able to get the first few letters to transmit not the whole array, here is my code:

//tx serial
#include <avr/io.h> 

#define F_CPU 16000000 
#define BUAD 9600 
#define BUAD_RATE_CALC ((F_CPU/16/BUAD) - 1)  


int main(void){  

    char ar[]= "hello";

    //High and low bits
    UBRR0H = (BUAD_RATE_CALC >> 8); 
    UBRR0L = BUAD_RATE_CALC; 
    //////////////// 
    //transimit and recieve enable
    UCSR0B = (1 << TXEN0)| (1 << TXCIE0) | (1 << RXEN0) | (1 << RXCIE0); 
    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);  //8 bit data format
    ////////////////////////////////////////////////////////////////
    int i = 0;

    while (1){  

    while (( UCSR0A & (1<<UDRE0))  == 0){};
        for (i = 0; i < strlen(ar); i++){ 
            UDR0 = ar[i]; 
        }
    }
}

What would the problem be with this?

Answer 1

Not quite sure, just a fast guess. Maybe you should put the while(UDRE0 == 0){} inbetween sending characters. I believe it's to wait until one character has been sent.

for (i = 0; i < strlen(ar); i++){ 
   while (( UCSR0A & (1<<UDRE0))  == 0){};
   UDR0 = ar[i]; 
}

Answer 2

So I tried your code and it works!! However when I did, as expected it kept printing out hello continuously however I made it return zero to make it print hello out once here is the code:

            //data_buffer 

            //tx serial

            #include <avr/io.h> 

            #define F_CPU 16000000 
            #define BUAD 9600 
            #define BUAD_RATE_CALC ((F_CPU/16/BUAD) - 1)  
            #define buffer_size 128
            #define boolen 0
            int main(void){  
                char br;
                char ar[]= "hello";
                char buffer[10]; 
                //High and low bits
                UBRR0H = (BUAD_RATE_CALC >> 8); 
                UBRR0L = BUAD_RATE_CALC; 
                //////////////// 
                //transimit and recieve enable
                UCSR0B = (1 << TXEN0)| (1 << TXCIE0) | (1 << RXEN0) | (1 << RXCIE0); 
                UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);  //8 bit data format
                ////////////////////////////////////////////////////////////////
                int i = 0;

                while (1){  
                /*while( (UCSR0A & (1<<RXC0))  == 0 ){}; 
                    br = UDR0;
                */

                while (( UCSR0A & (1<<UDRE0))  == 0){};

                        for (i = 0; i < strlen(ar); i++){ 
                            while (( UCSR0A & (1<<UDRE0))  == 0){};
                            UDR0 = ar[i]; 
                            if (i == (strlen(ar) - 1)){ 
                                return 0;
                            }
                        } 
                }

            }   

I would like to note the there are some random variables and things defined that I don't even use, just ignore them

Answer 3

You should make a new question for every other question you have... But well. The code below (Might be a bit arduino styled, but it might help the questioner).

The Setup code runs only once, at the start of your progam. Great to initialize any peripherals and/or send a hello message / startup routine. The Loop code runs continiously, usually this contains a program like blinking leds... or the security system of a nuclear powerplant. However, it's not designed to be returned from, it's designed to run forever. Though my code will catch you in a while(forever); if you were to return from it.

I haven't tested the code, but I recon it would be this:

#include <avr/io.h> 
#define F_CPU 16000000 
#define BUAD 9600 
#define BUAD_RATE_CALC ((F_CPU/16/BUAD) - 1)  

//Function definitions
void Setup(void);
void Loop(void);
void serialSetup(void);
void serialSend(char* sendString);

//Global variables.
char ar[]= "hello";

void Setup(){
//Code to be run once (At start).
    serialSetup();
    serialSend(ar);
}

void Loop(){
    //Code to be run continiously.
}

void serialSetup(){
    //Register settings
    //High and low bits
    UBRR0H = (BUAD_RATE_CALC >> 8); 
    UBRR0L = BUAD_RATE_CALC; 
    //transimit and recieve enable
    UCSR0B = (1 << TXEN0)| (1 << TXCIE0) | (1 << RXEN0) | (1 << RXCIE0); 
    UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);  //8 bit data format
}

void serialSend(char* sendString){
     for (int i = 0; i < strlen(sendString); i++){ 
         while (( UCSR0A & (1<<UDRE0))  == 0){};
         UDR0 = sendString[i]; 
     } 
}

int main(void){  
    Setup();
    while(1){
       Loop();
    }
while(1){}//If you ever return from Loop(); This while will catch you, so it won't continue doing randomness.           
}