Microcontroller LEd InterFacing

The first thing usually done while learning any microcontroller or embedded system is blinking an LED. The circuit below shows the circuit for Interfacing an LED.

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Here an LED is connected to the first pin of port0 (P0.0). The assembly program given below is simple and self explanatory.

;************************************************* ; ;Program: Blinking LED. ;Author: Srikanth ;Website: http://shree-electronics.com/ ;Description: Blinks an LED connected to P0.0 ;continuously ; ;************************************************* led equ P0.0 org 00h up: setb led ;Turn ON the LED acall delay ;call delay subroutine clr led ;Turn OFF the LED acall delay ;call delay subroutine sjmp up ;Loop delay:mov r7,#0ffh ;delay subroutine loop:mov r6,#0ffh djnz r6,$ djnz r7,loop ret end

The program is purposely made lengthy in order to explain some programming techniques such as subroutine, loop etc.