Serial Communication between 2 Arduino Uno using just Registers - c

Question

I need to transfer a string between 2 Arduino Uno, using serial communication without functions(just manipulating registers, such as UDR0).
I am able to send a string using
#define BAUD 9600
#define MYUBRR F_CPU/16/BAUD-1
void USART_Init(unsigned int ubrr)
{
UBRR0H=(unsigned char)(ubrr>>8);
UBRR0L=(unsigned char)ubrr;
UCSR0B=(1<<RXEN0)|(1<<TXEN0);
UCSR0C=(1<<USBS0)|(3<<UCSZ00);
}
void USART_Transmit(unsigned char data)
{
while(!(UCSR0A&(1<<UDRE0)));
UDR0=data;
}
void SendString(char *StringPtr)
{
while(*StringPtr !=0x00)
{
USART_Transmit(*StringPtr);
StringPtr++;
}
}
void setup()
{
USART_Init(MYUBRR);
}
void loop()
{
SendString("123456");
delay(1000);
}
but I have no idea how to copy the content of the UDR0 register at the other end. The function should be something like:
unsigned char USART_Receive(void)
{
while(!(UCSR0A&(1<<RXC0)))
return UDR0;
}
But I don't know how to actually use it; I need to save all those chars from the serial to a string, then show the string on a LCD connected to the second Arduino Uno, but every time when I attempt to receive more that one char it's all working very bad(blank spaces, a lot of zeros, invalid characters).
I read that if I have an LCD connected to the second arduino, it's much better to not use the USART_Receive() function, and implement it as an interrupt, but I don't know how to do that either.
Do you have any idea how to transfer the string to the other Arduino?

Answer 1

Perhaps try to put all the chars in an big array and then send that array to your LCD. That way, the time between reading one char and the next one is minimized. (UART is asynchronous, so if you're too slow, you miss the requested data).