STC89C52 microcontroller lights up the LED light

Light up the LED light

1. What is LED

The full name of LED is semiconductor light-emitting diode. It is made of semiconductor materials and is a light-emitting device that directly converts electrical energy into light energy and electrical signal into optical signal. It is characterized by low power consumption, high brightness, bright colors, vibration, and long life. It has the advantages of long life (80,000-100,000 hours of normal light emission) and cold light source, making it a true "green lighting".

2. LED working parameters

The symbol of LED (Light Emitting Diode) in the circuit diagram is:

It has the basic characteristics of a diode: forward conduction and reverse blocking. To light up the LED, operating current needs to flow from the forward direction.

The working voltage drop of ordinary light-emitting diodes is: 1.6~2.1V.

Working current: 1~20mA.

With the passing current of the LED in the picture, we can follow Ohm's law I (current) = U (voltage) / R (resistance)

It can be calculated as 3mA.

3. Schematic analysis

4. C language knowledge

Keywords: sbit

Function: bit definition

General format: sbit identifier = address value;

For example: sbit LED1 = P1^0;

Note: The "P" in P1 in the address value must be a capital P

5. Write code

1. Turn on LED1

#include // Reference 51 header file

sbit LED1 = P1^0; // P must be uppercase to control the red light

void main(){ // After the program is compiled, the main function itself will loop

LED1 = 0; // When set to 0, input a low level and the first light of the microcontroller will light up.     

// LED1 = 1; // When set to 1, input a high level, the first light of the microcontroller will go out

}

Rendering:

2. Turn on LED1, 3, 5, and 7, and turn off LED2, 4, 6, and 8;

#include

void main(){ // main function itself will loop

while(1){ // Generally, when executing a program, you need to write a while loop body to execute the code.

P1 = 0XAA; // 1010 1010   // Make LED1, 3, 5, 7 light up

}

} 

Rendering: