[51] 8051 Timer Interrupt Programming.

[Titus Manoj Kumar]

Dear All,

Am working on 8051 Timer Interrupt Programming.

Specs:

Timer 0 Mode 1.
Need to blink an Led for 30 seconds.
Xtal Freq: 11.0592Mhz.

I've pasted the code below. Could you please identify the errors in it. If so could you give me the complete code for it. It'l be a great help. Thanks.

code :

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
#include<reg51.h>
sbit led = P2^0;        //LED connected to D0 of port 1
 
void timer(void) interrupt 1        //interrupt no. 1 for Timer 0
{
int x;
for (x=0; x<600 ; x++)
{
led=~led;       //toggle LED on interrupt
TR0 = 0;
}
}
main()
{
TMOD = 0x01;        // mode1 of Timer0
TH0 = 0x4C;     // initial values loaded to timer
TL0 = 0x00;
IE = 0x82;      // enable interrupt
TR0 = 1;        //start timer
while(1);       // do nothing  
}

---

 

[udayan92]

It looks like you did not call the timer function in the main function.

 

[Disha Karnataki]

Dear All,

Am working on 8051 Timer Interrupt Programming.

Specs:

Timer 0 Mode 1.
Need to blink an Led for 30 seconds.
Xtal Freq: 11.0592Mhz.

I've pasted the code below. Could you please identify the errors in it. If so could you give me the complete code for it. It'l be a great help. Thanks.

code :

---

Code C - [expand]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
#include<reg51.h>
sbit led = P2^0;        //LED connected to D0 of port 1
 
void timer(void) interrupt 1        //interrupt no. 1 for Timer 0
{
int x;
for (x=0; x<600 ; x++)
{
led=~led;       //toggle LED on interrupt
TR0 = 0;
}
}
main()
{
TMOD = 0x01;        // mode1 of Timer0
TH0 = 0x4C;     // initial values loaded to timer
TL0 = 0x00;
IE = 0x82;      // enable interrupt
TR0 = 1;        //start timer
while(1);       // do nothing  
}

---

tell us what are problems you are facing while dumping it on hardware. Does the leds are lit continuoulsy i.e either on/off (with no toggle)?
first of all you have not cleared the timer flag & hence the interrupt will not terminate.
another do not use

while(1);

it will again start initializing from starting & hence the timer flag will never be set.
So use something like this:

while(1)
{
//do some work here
//may be blinking leds on some other ports .
}

- - - Updated - - -

It looks like you did not call the timer function in the main function.

but, that is not timer function to blink leds it's the ISR & the controller will jump only when interrupt occurs & hence he need not to call that in the main function.