Why the leds on Port C keeps on blinking?

[Einly]

Dear all,

I am trying to send data from pc to the pic. and from pic to the pc. When I send a byte from the pc to the pic, the pic will get the character and light a led. I connect a max232 between the pc and the pic.

My program looks like this:
#include <16f876.h>
#fuses HS,NOWDT,NOLVP,NOPROTECT,PUT,BROWNOUT

#use delay(clock=20000000)
#use rs232(baud=115200, xmit=PIN_C6, rcv=PIN_C7)

#byte PORTC=7

byte a;

#int_rda
void serial_isr()
{
a=getc();
portc=a;
}

void main()
{
set_tris_c(0x80);
enable_interrupts(global);
enable_interrupts(int_rda);

portc=0x02;

do {
} while (1);
}

However, when I send a byte, e.g. 1, the led that is connected to PIN C0 keeps on blinking. Later I change my program to just lights the PIN_C0 without receive data from the pc to check whether the problem is caused by the interrupt. However, the LED is still blinking if the rs232 between the pc and pic still there. If I remove the connection, then it is ok (just light on, without blinking. May I know anyone hav any idea why does this happen?

Thanks
_________________
Einly

[ckielstra]

The program version as shown above will blink the led on incomming serial data. So, if the led is blinking your PC must be transmitting data (even though you might 'think' it is not). Check all programs running on your PC.