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UART Problem : between atmega32 and atmega8

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E

engallam

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Hi I'm try to connect atmega32a with atmega8a using UART protocal but...

(in simulation)
- when I send byte from atmega32 to atmega8, the connection work good
- when I send byte from atmega8 to atmega32,the connection not work

(in real)
- the data recived by atmega8 (transmuted by atmega32) , be wrong data (Ex: when i send (1) from atmega32 the data received by atmega8 be (24)

- when I send byte from atmega8 to atmega32, the connection not work


what the problem ??!



code of atmega32a

Code: 
#define  F_CPU 16000000
#include <avr\io.h>
#include <avr\pgmspace.h>
#include <avr\interrupt.h>
#include <util\delay.h>
#include <math.h>

#define ButtonPort		PORTA			// Buttons port
#define ButtonDir		DDRA			// Buttons Direction
#define ButtonPin		PINA			// Buttons port
#define Down			0			// Down Button
#define Up				1			// Up Button
#define Right			2			// Right Button
#define Left			3			// Left Button
#define Run				4			// Run Button
#define Back			5			// Back Button

int main(void) 
{
	DDRB=0xff;	
	PORTB=0x00;
	ButtonDir=0x00;		
	ButtonPort=0xff;
	uint16_t baud = 2400;


	uint16_t UBRR_Value = lrint (( F_CPU / (16 * baud) ) - 1); 
		
	UBRRL = (uint8_t) UBRR_Value;
	UBRRH = (uint8_t) (UBRR_Value >> 8);
	UCSRB = (1<<RXEN) | (1<<TXEN);  
	
    UCSRC |= (1 << UPM1);	//Sets parity to EVEN
	UCSRC |= (3 << UCSZ0);	//8-bit data length

	while (1)
	{

		if (bit_is_clear(ButtonPin,Up))
		{
			_delay_ms(500);
			while( ! (UCSRA & (1<<UDRE) ) );
			UDR = 1;
		}
		if (bit_is_clear(ButtonPin,Down))
		{
			_delay_ms(500);
			while( ! (UCSRA & (1<<UDRE) ) );
			UDR = 2;
		}
		if (bit_is_clear(ButtonPin,Right))
		{
			_delay_ms(500);
			while( ! (UCSRA & (1<<UDRE) ) );
			UDR = 4;
		}
		if (bit_is_clear(ButtonPin,Left))
		{
			_delay_ms(500);
			while( ! (UCSRA & (1<<UDRE) ) );
			UDR = 8;
		}
		if (bit_is_clear(ButtonPin,Run))
		{
			_delay_ms(500);
			while( ! (UCSRA & (1<<UDRE) ) );
			UDR = 16;
		}
		

		while (! (UCSRA & (1 << RXC)) );
			PORTB= UDR; 
		 _delay_ms(500);
	}

}

code of atmega8a

Code: 
#define  F_CPU 16000000
#include <avr\io.h>
#include <avr\pgmspace.h>
#include <avr\interrupt.h>
#include <util\delay.h>
#include <math.h>



int main(void) 
{
	DDRB=0xff;	
	PORTB=0x00;

	uint16_t baud = 2400;
	char data=5;	

	uint16_t UBRR_Value = lrint (( F_CPU / (16 * baud) ) - 1); 
		
	UBRRL = (uint8_t) UBRR_Value;
	UBRRH = (uint8_t) (UBRR_Value >> 8);
	UCSRB = (1<<RXEN) | (1<<TXEN);  
	
        UCSRC |= (1 << UPM1);	//Sets parity to EVEN
	UCSRC |= (3 << UCSZ0);	//8-bit data length

	while (1)
	{
		while (! (UCSRA & (1 << RXC)) );
			PORTB= UDR; 
		 _delay_ms(500);

		while( ! (UCSRA & (1<<UDRE) ) );
			UDR = data;
		_delay_ms(500);
	}

}
 

At a glance, the first thing that trikes the eyes is the addition of a delay in the serial pooling routine; In real world it could even work if you tap each button once at long intervals (assuming that there is a debouncer in hardware), but surelly would not work in simulation, where the things happens in 'slow motion' from our perspective. I did not look at the remaining code after that.
 

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