51 MCU Learning Notes——1. Custom delay function lights up and controls the flashing seconds of LED and uses Proteus to simulate

#include

#define LED P0

void delay(); //delay for one second

void main() //Bitwise operation to light up the small light 

{

  unsigned int i;

  while(1)

  {

  for(i = 0;i<8;i++)

{

LED = ~(0X01< delay();

}

  }

  } 

void delay()   //delay for one second

{

  unsigned int i,j;

  for(i = 0;i<83;i++)

{

for(j = 0;j<1000;j++)

{

;

}

}

 }

Since the blogger is at home during the winter vacation and does not have a 51 single-chip microcomputer, I used Proteus to build a simple circuit, wrote the file with keil5 to generate a .hex file, and then added it to Proteus to run. The specific operations are as follows:

Then check the following options:

Then save the written code and finally open the Proteus software.

Build the circuit as follows:

Then insert the code to combine with the circuit:

Select the .hex file to confirm, then run in the lower left corner:

The operation is as follows, blue means the small light is running normally:

We can see the small lights cycle from the first light to the eighth light.

Careful friends can see that the delay time set by our delay() function is one second. Why is it one second? The control here is quite clever. Two for() loop statements are used. The outer loop is executed 83 times and the inner loop is executed 1000 times, which means that the total execution is 83 * 1000 times. In C language, the number of seconds to execute a statement can be observed by setting breakpoints before and after. In order to deeply understand why the program can reach 1 second after executing 83 * 1000 times, we set a breakpoint before and after this statement respectively, and roughly judge the program's pointing time by observing the time difference between the two endpoints: