51 single chip microcomputer learning notes (2)

LED Light flashing

Premise ： Learn how to create and complete projects LED Lighting experiment , If you haven't learned , Please click the following to jump ：51 MCU learning notes （1）

Thinking before experiment ： Last study note , We have learned how to light a light-emitting diode （LED）, So how can we make it flash this time ？ We know , Light emitting diodes have single conductivity , And only when a current circuit is formed can it glow , And in SCM , One end of the LED has been connected to the positive pole , We just need to be on the other side （IO mouth ） Connect it to low level （0） It can be lit , Then if we let the other end change high and low levels with a certain period of time , Then we can realize the flashing of light-emitting diodes ！ Let's start the experiment ！
- New project , Name it template, The new document is named main.c, Save in the project folder . take c Add files to the project . Start editing the code .

#include <reg51.h> // introduce 51 SCM library file 

typedef unsigned int u16;   // take unsigned int In the code, use u16 Instead of , namely u16 i; Is to define an unsigned integer variable i

sbit led = P2^0;            // Define SCM pins （IO）P2^0 by led, This pin is connected with a light-emitting diode , And one end of it has been connected to the positive pole 

void delay(u16 i)           // Define the delay function 
{
    while(i--);             // Use while Function to realize self subtraction , When i=0 when , Out of the loop , Return the main function 
}

void main()                 // Define the main function , The program enters from here 
{
    while(1)                // Definition while loop , Condition is 1（ really ）, namely while It's been circulating 
    {
        led = 0;            // Set up P2^0 The pin is low level , Forming loop ,LED Lighten up 
        delay(50000);       // Call delay function , About time delay 450ms
        led = 1;            // Set up P2^0 The pin is high level , At this time, both ends of the LED are high ,LED Extinguish 
        delay(50000);       // Call delay function , About time delay 450ms
    }
}

• After the code is written , Compile it , Open the burning software to compile the generated hex The file is written into the single chip microcomputer for testing and phenomenon observation .

LED Running water lamp

Thinking before practice ： How to achieve LED Running water lamp ？ First of all, let's understand from the concept of water lamp , Water light refers to the bulbs that are currently placed one after another in sequence , And then next , The bulbs light up in turn , That is, the special flashing mode of the former off and the latter on , In the last experiment, we learned about light-emitting diodes （LED） The twinkle of , Now we want to realize the flashing of a row of diodes . First we need to know , In the circuit of MCU , That row of light-emitting diodes is common , That is, one end of them is connected to high level , Then we just need to turn on each LED in turn （IO Low level ） After extinction （IO High level ）, Water lamp can be realized ！ Then let's start the experiment ！

- New project , Name it template, The new document is named main.c, Save in the project folder . take c Add files to the project . Start editing the code .

#include <reg51.h> // introduce 51 SCM library file 
#include <intrins.h> // Introduce the library file with left-right shift function 

typedef unsigned int u16;   // take unsigned int In the code, use u16 Instead of , namely u16 i; Is to define an unsigned integer variable i
typedef unsigned char u8;   // take unsigned char In the code, use u8 Instead of , namely u8 i; Is to define an unsigned variable i

#define led P2 // Use a macro to define , Defining variables led For single chip microcomputer P2.0-2.7 Pin 

void delay(u16 i)           // Define the delay letter 
{
    while(i--);             // Use while Function to realize self subtraction , When i=0 when , Out of the loop , Return the main function 
}

void main()                 // Define the main function , The program enters from here 
{
    u8 i;                   // Define unsigned character variables i
    led = 0xfe;             // The variable led The magnitude is 0xfe, Convert to binary, i.e  1111 1110, That is, only P2.0 Low level 
    delay(50000);           // Call delay function , About time delay 450ms
    while(1)                // Definition while loop , Condition is 1（ really ）, namely while It's been circulating 
    {
        for(i=0;i<7;i++)    // Definition for loop , loop 7 Time 
        {
            led = _crol_(led,1);   // Call the shift left function , One bit left at a time , namely 1111 1110 ——> 1111 1101,0 Move one bit to the left in turn 
            delay(50000);          // Call delay function , About time delay 450ms
        }                          // After the left shift ,led = 0111 1111 0x7f
        for(i=0;i<7;i++)           // Definition for loop , loop 7 Time 
        {
            led = _cror_(led,1);   // Call the shift right function , One bit left at a time , namely 0111 1111 ——> 1011 1111,0 Move one bit to the right 
            delay(50000);          // Call delay function , About time delay 450ms
        }
    }
}

• After the code is written , Compile it , Open the burning software to compile the generated hex The file is written into the single chip microcomputer for testing and phenomenon observation .

thus , You've learned to LED Flashing and LED Running water lamp , May you sing all the way ！