Write an assembly language program in 8051 to generate a 10 ms delay using Timer 1 in Mode 1 and toggle an LED connected to Port 1.0 continuously.

AIM

To develop an 8051 microcontroller assembly program that uses Timer 1 in Mode 1 to generate a 10 ms delay and toggles an LED connected to Port 1.0. 8051.

APPARATUS REQUIRED

8051 Microcontroller Trainer Kit (or simulator like Keil uVision, Proteus, or 8051 IDE) LED (connected to Port 2.0) 10kΩ Resistor (as current limiter) Connecting Wires & Breadboard (for practical hardware) Computer with IDE/Assembler for code development and simulation.

ALGORITHM

Set Port 1.0 as an output by initializing it low (P1.0 = 0). Configure Timer 1 in Mode.Load Timer 1 registers with TH1 = 0xDC and TL1 = 0x00 to obtain a 10 ms delay at 12 MHz. Clear TF1, start Timer 1 (TR1 = 1), and wait until TF1 becomes 1. Stop Timer 1 (TR1 = 0) and clear TF1. Toggle the state of Port 1.0 (P1 ^= 0x01). Repeat the delay and toggle steps indefinitely inside the main loop.

PROGRAM

#include<reg51.h>
void delay();
void main()
{
    P1 = 0x00;
   TMOD = 0x10;  
    while(1){
        P1 = 0xFF;
        delay();
        P1 = 0x00;
        delay();
    }
}

void delay()
{
    TH1 = 0xDC;  
    TL1 = 0x00;  
    TR1 = 1;     
    while(TF1 == 0);  
    TR1 = 0;     
    TF1 = 0;     
}

OUTPUT

RESULT

Successfully designed and verified an 8051 Assembly program to toggle an LED at Port 1.0 with a precise 10 ms interval using Timer 1 in Mode 1. Demonstrated timer initialization, delay loop, and I/O port manipulation in 8051 Assembly.