Interfacing on LED Push Button

Interfacing on LED Push Button

Description: The 89V51RD2 is the microcontroller used here. The circuit is so designed that when push button suppose S1 is depressed the LED D1 goes ON.

Connection Of LED: Never connect the LED directly with V_cc (output voltage which comes directly) it may burn your LED. Always connect the led with resistance.

Electrical Switch: The switch is a basic input device used to control operation of any output device using the microcontroller or control unit. It basically breaks the electrical circuit and interrupts the flow of current.

Connection of Electrical Switch: In circuit pull up and pull down resistor use to convert infinite or zero resistance into the digital signals. On the basis of pull up and pull down resistor .We can interface the switch in two way.

Positive Logic: In this we use a pull down resistor connected to the ground .When pressed the switch logic assert high and when disconnect the switch logic assert low.

Negative Logic: In this we use a pull up resistor connected to V_cc. When we press switch the logic assert low and when disconnected logic assert high.

Algorithm to control the led using the switch:

1 Microcontroller pin connected to LED makes the output.

2 Microcontroller pin connected to switch makes the input.

3 If switch is pressed LED is high or either makes it low.