Hi, it´s me once more, with my c programming questions.

I made a program that echoes any input using the serial interruption and thanks god (and your help) its finally working OK.

My question is:

If I now try to make a printf, putchar, nothing happens. I think this might be because it enters the interrupt function before outputing the message.

here is the code:

<pre>
/*------------------------------------------------
includes
------------------------------------------------*/
#include <stdio.h>
#include <reg52.h>

/*------------------------------------------------
declarations
------------------------------------------------*/
#define XTAL 11059200

/*------------------------------------------------
declarations
------------------------------------------------*/
void serialini (int baud);
void serialint (void);

/*------------------------------------------------
The main C function. Program execution starts
here after stack initialization.
------------------------------------------------*/
void main (void) {

serialini(19200); /* Inicialize serial: baudrate = 9600 */
printf ("hola\n");
while(1); /* infinite loop */

}

/*------------------------------------------------
Setup the serial port for 9600 baud at 11.0592MHz.
------------------------------------------------*/
void serialini (int baud){

EA = 0; /* disable interruptions */
PCON |= 0x80; /* PCON: double baudrate */
SCON = 0x50; /* SCON: mode 1 8-bit UART, enable rcvr */
TMOD |= 0x20; /* TMOD: timer 1, mode 2, 8-bit reload */
TH1 = 256-((XTAL/192)/baud); /* TH1: reload value */
ES = 1; /* ES: enable serial int. */
TR1 = 1; /* TR1: timer 1 run */
TI = 0;
RI = 0;
EA = 1; /* enable interruptions */
}

/*------------------------------------------------
Serial interruption, echos the incoming byte
------------------------------------------------*/
void serialint (void) interrupt 4 using 2 {
/*------------------------------------------------
Received data interrupt.
------------------------------------------------*/
char c;

if (RI != 0){
RI = 0;
c = SBUF;
SBUF = c;
}

/*------------------------------------------------
Transmitted data interrupt.
------------------------------------------------*/
if (TI != 0){
TI = 0;
}

}
<\pre>