interrupts

hi
i am writting a program to recieve data throuth serial port (UART) of
AT89S51 microcontroller.Using the interrupts i have wriiten the ISR as

void serial_ISR () interrupt 4 using 2
{
if(RI == 1)
{
led = on;
RI=0;
}}
the interrupt is occuring but the led do not get ON
if i write ISR like this

void serial_ISR () interrupt 4 using 2
{
led = on;
if(RI == 1)
{
RI=0;}
}
now led gets on
this means it is getting some thing but why RI == 1; is not working
do the recieve flag automatically gets clear

You need to clear RI
**broken link removed**

I posted a reply very early this AM but it is gone along with several others.

First use the # tool to place code tags around your code to make it readable.
For testing I would use 3 LEDs or breakpoints if you have run control. The serial interrupt can be set by the RX or TX. Check for both and neither which in theory should not happen. Check anyway.

3v0 said:

I posted a reply very early this AM but it is gone along with several others.

Click to expand...

I think the problem is that he started more than one thread with the same topic.

@colin mac (and everyone)
When you see a duplicate thread please post in the one that already has replies. Let the other one die.