Re: [avr-gcc-list] using UART to send from within SIGNAL(SIG_UART_RECV) function

[Karsten Becker]

Joerg Wunsch wrote:

> Karsten Becker <address@hidden> wrote:
>
> > When I try to send from within the SIGNAL(SIG_UART_RECV)  function, the 
> > sending stops after one character.
> > Is there any way to make it possible to send from within this function?
>
> Guess you gotta post your code in order to get help.
>
> Anyway, it's IMHO a bad idea to abuse an interrupt service routine to
> do this kind of task, in particular since you're most likely using a
> busy-wait loop in order to see when to start sending the next
> character.
>
> It's usually better to minimize the code inside the ISRs, and just set
> a bit that can be evaluated inside the program's main loop.  Something
> like
That is exactly what i wanted to replace by the Interrupt driven method 
because of the "high" latency.
Maybe one of the problems is that the code inside the 
SIGNAL(SIG_UART_RECV) has 178lines in original. But there are many if 
that lead in something like 4-6 cycles to the bit longer PRINT routine.
I'm using 115200Baud.
What I do is:

#define PRINT(string) (UART_PrintfProgStr(PSTR(string)))

void UART_PrintfProgStr(u08* pBuf)
{
   /* wait for UART to become available */
   while(!UART_Ready);
   UART_Ready = 0;
   /* Indicate to ISR the string to be sent */
   pUART_Buffer = pBuf;
   /* Send first character */
   outp( PRG_RDB(pUART_Buffer), UDR );
}

/* UART Transmit Complete Interrupt Function */
SIGNAL(SIG_UART_TRANS)     
{
   /* Test if a string is being sent */
   if (pUART_Buffer!=0)
   {
       /* Go to next character in string */
       pUART_Buffer++;
       /* Test if the end of string has been reached */
       if (PRG_RDB(pUART_Buffer)==0)
       {
           /* String has been sent */
           pUART_Buffer = 0;
           /* Indicate that the UART is now ready to send */
           UART_Ready   = 1;
           return;
       }
       /* Send next character in string */
       outp( PRG_RDB(pUART_Buffer), UDR );
       return;
   }
   /* Indicate that the UART is now ready to send */
   UART_Ready = 1;
}

SIGNAL(SIG_UART_RECV)     
{
   /* Store received character */
   UART_RxChar = inp(UDR);
   if (UART_RxChar ==5) {
       PRINT("Bad choice, try again");
   }

Thanks, Karsten


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