Cannot receive data from PC serially connected to ATMEGA8

[yviswanathbe]

Hi,
I am working on AVR Atmega8 Microcontroller.
I am using Code Vision AVR Compiler.
I am facing problem in serial communication.
I am able transmit data to the PC but i am not able to receive data from the PC.

What could be the problem?
Please suggest me something.

Thanks& Regards,
Y.Viswanath.

 

[AMK1971]

codevision communication error

One possibility is that problem is in the configuration of your serial port, Check if the 'receiver' and 'receive complete interrupt' both are enabled.

 

[yviswanathbe]

codevision serial communication tutorial

Hi,
here are my USART configuration details:

	UCSRA=0x00;
	UCSRB=0x18;
	UCSRC=0x86;
	UBRRH=0x00;
	UBRRL=0x19;

n
here are the functions i have used for Tx and Rx

void serial_send(unsigned char dat)
{
       while((UCSRA & 0x20)==0x00); //wait for UDRE flag
       UDR=dat;
       while((UCSRA & 0x40)==0x00); //wait for TXC flag.
}
unsigned char serial_read()
{
	if(!UCSRA.7)
	{
		return UDR; 
	} 
}

i think i have everything correct.

Please let me know if i am doing anything wrong?

Thanks,
Y.Viswanath

Added after 11 minutes:

HI,
Now i am able to receive the data as well as transmit the data.
Problem is with RX function.

Here is updated code.

unsigned char serial_read()
{
	while((UCSRA & 0x80)==0x00);
	{
		return UDR; 
	} 
}

 

[sanliedinata]

atmega8 codevision avr tutorial

unsigned char serial_read()
{
	if(!UCSRA.7) --> while(!UCSRA.7)
	{
		return UDR; 
	} 
}

have you tried this?

 

[yviswanathbe]

bad isr interrupt atmega8

could any body send me some sample code for serial communication using ISR.
using codevision AVR.

 

[sanliedinata]

+codevision +txc

hmm, what kind of sample do you want??
here is one of multiple bytes tx to micro.. take a look.

data = receive();
switch (state){
    case 0: // wait for sync
        if(data == SYNC) state = 1;
        break;

    case 1: // got sync, get byte count
        byte_count = data;
        counter = 0;
        checksum = 0;
        state = 2;				
        break;

    case 2:	// get data
        buffer[counter] = data;
        checksum ^= data;
        counter++;
        byte_count--;
        if(byte_count == 0) state = 3;
        break;
     
    case 3: // grab checksum
        if(checksum == data) 
        {
	// packet is valid
        }
        else
        {
	// packet is bad
        }
        state = 0;
        break;
}

Added after 1 minutes:

oopss, sorry.. my bad.. but who knows you need it someday..

 

[yviswanathbe]

Re: ATMEGA8 help????

Hi,
Thanks for sharing the code.

I need how to configure Interrupt Service Routine(ISR) for Serial Communication.

I have used CodeVisionAVR for sample code,but it is giving lots of code for ISR.i.e.,error frame checkingh,parity checking.
Do i need to do all the above to interact with my microcontroller from PC.

please post some tutorials on AVR ISR programming.

Thanks,
Viswanath.

 

[nandhu015]

Re: ATMEGA8 help????

Hai

Check out the tutorial at avrfreaks.net

Nandhu