sending data to usart using atmel studio avr gcc

[Areeha Durrani]

Hello..I am trying to send data to usart so that when i type a character 'a' to it it should turn the led on and if anything else is typed it should turn it off..I have written the code but i think i am missing something..kindly help...
My code is:
#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <stdio.h>
// the USART circuitry within the AVR really likes clock frequencies divisible by 1.8432MHz. If your clock source is not divisible by 1.8432 you will have a percentage of error which will result in unstable communications.
//using formula for setting the ubrr value
//as long as the error rate is less 0.5% it will result in solid communication
#define BAUDRATE 9600
#define BAUD_PRESCALLER (((F_CPU / (BAUDRATE * 16UL))) - 1)
//Declaration of our functions
void USART_init(void);
unsigned char USART_receive(void);
void USART_send( unsigned char data);
void USART_putstring(char* StringPtr);

char String[]=""; //String[] is in fact an array but when we put the text between the " " symbols the compiler threats it as a String and automatically puts the null termination character in the end of the text
unsigned char data,a;
int main(void){
//DDRD = 0b00000010;
//PORTD=0x00;
DDRB |=(1<<PORTB5);
PORTB=0x00;
USART_init(); //Call the USART initialization code

while(1){ //Infinite loop
//USART_putstring(String); //Pass the string to the USART_putstring function and sends it over the serial
//USART_send(data);
_delay_ms(3000); //Delay for 3 seconds so it will re-send the string every 5 seconds
data=getchar();
USART_send(data);

if (data=='a')
{
PORTB|=(1<<PORTB5);
_delay_ms(500);
}
else
{PORTB&=~(1<<PORTB5);
}
}
return 0;
}

void USART_init(void){
//UBRRn is a baudrate register
//UMSELn bit in USART Control and Status Register C (UCSRnC) selects
//between asynchronous and synchronous operation
UBRR0H = (uint8_t)(BAUD_PRESCALLER>>8); // Baud Rate Register upper 4 bits
UBRR0L = (uint8_t)(BAUD_PRESCALLER); // Baud Rate Register lower 4 bits
//enable the transmission and receive functionality independently.
//Both the RXENn bit (Receive Enable) and the TXEN(TXENn) bit (Transmitter Enable)
//are both located in the B Register (UCSRnB)
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
//All of our configuration options are located in Register C
UCSR0C = (3<<UCSZ00); //Set frame
}

unsigned char USART_receive(void){

while(!(UCSR0A & (1<<RXC0)));//Wait until data is received
return UDR0; // Read the data from the RX buffer

}

void USART_send( unsigned char data) //write byte to serial port
{

while(!(UCSR0A & (1<<UDRE0)));// Wait until buffer is empty
UDR0 = data;// Send the data to the TX buffer

}

void USART_putstring(char* StringPtr){

while(*StringPtr != 0x00){
USART_send(*StringPtr);
StringPtr++;}

}

 

[Harald Kapp]

The issue seems to be here

data=getchar();

As far as I understand you want to type on the PC's keyboard, so instead of getchar() you nee dto rad from the USART using USART_receive().
On the PC side you need to attach to the serial port e.g. via a terminal program to connect to the AVR's UART, then type 'a'.

 

[Areeha Durrani]

The issue seems to be here

As far as I understand you want to type on the PC's keyboard, so instead of getchar() you nee dto rad from the USART using USART_receive().
On the PC side you need to attach to the serial port e.g. via a terminal program to connect to the AVR's UART, then type 'a'.

Thanks alot it worked...
But I have a confusion..I want to initialize my esp8266 wifi module...whose code I had worked on arduino but now since em New to avr so don't know why my code is giving me errors...kindly help me with that..

 

[Areeha Durrani]

This is my code...for using my wifi module as an access point..
#include <avr/io.h>
#define F_CPU 16000000UL
#include <avr/io.h>
#include <util/delay.h>

#define BAUDRATE 9600
#define BAUD_PRESCALLER (((F_CPU / (BAUDRATE * 16UL))) - 1)
#define DEBUG true
#define String espmode
#define espmode "3"
#define SSid "KFRL-4"
#define password "RFID5678"

void Esp_init(void);
unsigned char Esp_receive(void);
void Esp_send( unsigned char data);
void Esp_putstring(char* StringPtr);
void wifiSetup(String,String,String);
void sendData(String,const,boolean);

char String[]="Hello world";
unsigned char data;

int main(void)
{
Esp_init();
while(1)
{
wifiSetup(String espmode,SSid,password);
if (Esp_receive()!=0X00)
{
_delay_ms(1000);
int ConnectionId=Esp_receive()-48;
Esp_putstring(String);
Esp_send(data);
}
}
return 0;
}
void sendData(String Command,const int timeout,boolean debug)
{
String response="";
Esp_receive(Command);
long int time=millis();
while(time+timeout)>millis;
{
while(Esp_receive()!=0X00);
{
char c=Esp_receive();
response+=c;
}
}
if(debug)
{
Esp_putstring(response);
}
return response;
}
void wifiSetup(String mode,String SSid,String pass)
{
sendData("AT\r\n",2000,DEBUG); //reset mode
String mode0= "AT+CWMODE=";
mode0 += mode;
mode0 += "\r\n";
sendData(mode0,2000,DEBUG); // configure as access point
String ssidset="AT+CWJAP=\"";
ssidset += SSid ;
ssidset += "\",\"" ;
ssidset += pass ;
ssidset += "\"" ;
ssidset += "\r\n" ;
sendData(ssidset,5000,DEBUG);
return;

}

void Esp_init(void)
{
//UBRRn is a baudrate register
//UMSELn bit in USART Control and Status Register C (UCSRnC) selects
//between asynchronous and synchronous operation
UBRR0H = (uint8_t)(BAUD_PRESCALLER>>8); // Baud Rate Register upper 4 bits
UBRR0L = (uint8_t)(BAUD_PRESCALLER); // Baud Rate Register lower 4 bits
//enable the transmission and receive functionality independently.
//Both the RXENn bit (Receive Enable) and the TXEN(TXENn) bit (Transmitter Enable)
//are both located in the B Register (UCSRnB)
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
//All of our configuration options are located in Register C
UCSR0C = (3<<UCSZ00); //Set frame

}

unsigned char Esp_receive(void){

while(!(UCSR0A & (1<<RXC0)));//Wait until data is received
return UDR0; // Read the data from the RX buffer

}

void Esp_send( unsigned char data) //write byte to serial port
{

while(!(UCSR0A & (1<<UDRE0)));// Wait until buffer is empty
UDR0 = data;// Send the data to the TX buffer

}

void Esp_putstring(char* StringPtr){

while(*StringPtr != 0x00){
Esp_send(*StringPtr);
StringPtr++;}

}

 

[Harald Kapp]

But I have a confusion..I want to initialize my esp8266 wifi module..

I'm sorry, I'm not familiar with the esp8622 module.

 

[Areeha Durrani]

That's okay thanks..

 

[Areeha Durrani]

N what if u want to send string to the usart instead of character??

 

[Harald Kapp]

A string is a series of charactes, so simply send one character after the other until you reach the end of the string. Wait for the UART to finish transmission of a character before you send the next one.

 

[Areeha Durrani]

like what changes do i need to make in the code?

 

[Harald Kapp]

The routine is already there in your code:

void Esp_putstring(char* StringPtr){

while(*StringPtr != 0x00){
Esp_send(*StringPtr);
StringPtr++;}

}