*Example 1:
Use P3 port to light up 8 LEDs in sequence
#include<reg51.h> // Include the header file for microcontroller registers / Function: Delay for a period of time
void delay(void)
{
unsigned char i,j;
for(i=0;i<250;i++)
for(j=0;j<250;j++)
;
}
/ Function: Main function
void main(void)
{
while(1)
{
P3=0xfe; // First LED on
delay(); // Call delay function
P3=0xfd; // Second LED on
delay(); // Call delay function
P3=0xfb; // Third LED on
delay(); // Call delay function
P3=0xf7; // Fourth LED on
delay(); // Call delay function
P3=0xef; // Fifth LED on
delay(); // Call delay function
P3=0xdf; // Sixth LED on
delay(); // Call delay function
P3=0xbf; // Seventh LED on
delay(); // Call delay function
P3=0x7f; // Eighth LED on
delay(); // Call delay function
} / /
}
*Example 2:
Light up 8 LEDs in sequence by manipulating the P3 port address
#include<reg51.h> // Include the header file for microcontroller registers
sfr x=0xb0; // The address of P3 in memory is b0H, through sfr can define all internal 8-bit special function registers of 8051 microcontroller, manipulating address x is also manipulating P1 port
/
Function: Delay for a period of time
/
void delay(void)
{
unsigned char i,j;
for(i=0;i<250;i++)
for(j=0;j<250;j++)
; // Use loop to wait for several machine cycles, thus delaying for a period of time
}
/
Function: Main function
/
void main(void)
{
while(1)
{
x=0xfe; // First LED on
delay(); // Call delay function
x=0xfd; // Second LED on
delay(); // Call delay function
x=0xfb; // Third LED on
delay(); // Call delay function
x=0xf7; // Fourth LED on
delay(); // Call delay function
x=0xef; // Fifth LED on
delay(); // Call delay function
x=0xdf; // Sixth LED on
delay(); // Call delay function
x=0xbf; // Seventh LED on
delay(); // Call delay function
x=0x7f; // Eighth LED on
delay(); // Call delay function
}
}
*Example 3:Control LED flashing time with different data types
#include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for a period of time using integer data
/
void int_delay(void) // Delay for a longer period of time
{
unsigned int m; // Define unsigned integer variable, double-byte data, range 0~65535 for(m=0;m<36000;m++)
;
}
/
Function: Delay for a period of time using character data
/
void char_delay(void) // Delay for a shorter period of time
{
unsigned char i,j; // Define unsigned character variable, single-byte data, range 0~255 for(i=0;i<200;i++)
for(j=0;j<180;j++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char i;
while(1)
{
for(i=0;i<3;i++)
{
P1=0xfe; // Light up the LED at P1.0
int_delay(); // Delay for a longer period of time
P1=0xff; // Turn off
int_delay(); // Delay for a longer period of time
}
for(i=0;i<3;i++)
{
P1=0xef; // Light up the LED at P1.4
char_delay(); // Delay for a shorter period of time
} P1=0xff; // Turn off char_delay(); // Delay for a shorter period of time } }
*Example 4:Use microcontroller to control the first LED to light up
#include<reg51.h> // Include the header file for 51 microcontroller registers
void main(void)
{
P1=0xfe; // P1=1111 1110B, that is, P1.0 outputs low level
}
*Example 5:Use microcontroller to control an LED to flash: Understand the working frequency of the microcontroller #include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for a period of time
/
void delay(void) // The two voids mean no return value, no parameter passing {
unsigned int i; // Define unsigned integer, maximum value range 65535 for(i=0;i<20000;i++) // Do 20000 empty loops
;
}
/ Function: Main function (C language stipulates that there must be only one main function) / void main(void)
{
while(1) // Infinite loop
{
P1=0xfe; // P1=1111 1110B, P1.0 outputs low level
delay(); // Delay for a period of time
P1=0xff; // P1=1111 1111B, P1.0 outputs high level
delay(); // Delay for a period of time
}
}
*Example 6:Send the state of P1 port to P0, P2, P3 ports: Understand the function of I/O port pins
#include<reg51.h> // Include the header file for microcontroller registers
/ Function: Main function (C language stipulates that there must be only one main function) /
void main(void)
{
while(1) // Infinite loop
{
P1=0xff; // P1=1111 1111B, turn off LED
P0=P1; // Send the state of P1 port to P0 port
P2=P1; // Send the state of P1 port to P2 port
P3=P1; // Send the state of P1 port to P3 port
}
}
*Example 7:Use P0 and P1 ports to display the results of addition and subtraction #include<reg51.h>
void main(void)
{
unsigned char m,n;
m=43; // Decimal number 2×16+11=43
n=60; // Decimal number 3×16+12=60
P1=m+n; // P1=103=0110 0111B, result P1.3, P1.4, P1.7 lights up P0=n-m; // P0=17=0001 0001B, result P0.0, P0.4 lights off }
*Example 8:Use P0 and P1 ports to display the results of multiplication
#include<reg51.h> // Include the header file for microcontroller registers
void main(void)
{
unsigned char m,n;
unsigned int s;
m=64;
n=71;
s=m*n; // s=64*71=4544, requires 16-bit binary representation, high 8 bits sent to P1 port, low 8 bits sent to P0 port
// Since 4544=17*256+192=H3*16^2+H2*16^1+H1*16^0
// Dividing both sides by 256 gives 17+192/256=H3*16^2+H2+(H1*16^1+H0)/256
// Therefore, the high 8-bit hexadecimal number H3*16+H2 must equal 17, that is, 4544 divided by 256 gives the quotient
// The low 8-bit hexadecimal number H1*16+H0 must equal 192, that is, 4544 divided by 256 gives the remainder
P1=s/256; // Send the high 8 bits to P1 port , P1=17=11H=0001 0001B, P1.0 and P1.4 lights off
P0=s%256; // Send the low 8 bits to P0 port , P3=192=c0H=1100 0000B,P3.1,P3.6,P3.7 lights off
}
*Example 9:Use P1 and P0 ports to display the results of division
#include<reg51.h> // Include the header file for microcontroller registers
void main(void)
{
P1=36/5; // Calculate integer
P0=((36%5)*10)/5; // Calculate decimal
while(1)
; // Infinite loop to prevent the program from “running away”
}
*Example 10:Use self-increment operation to control the 8 LEDs on P0 port to light up in sequence
#include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for a period of time
/
void delay(void)
{
unsigned int i;
for(i=0;i<20000;i++)
;
}
/ Function: Main function
/ void main(void)
{
unsigned char i;
for(i=0;i<255;i++) // Note that the value of i must not exceed 255
{
P0=i; // Send the value of i to P0 port
delay(); // Call delay function
}
}
*Example 11:Use P0 port to display the result of logical “AND” operation #include<reg51.h> // Include the header file for microcontroller registers void main(void)
{
P0=(4>0)&&(9>0xab);// Send the logical operation result to P0 port
while(1)
; // Set infinite loop to prevent the program from “running away”
}
*Example 12:Use P0 port to display the result of conditional operation
#include<reg51.h> // Include the header file for microcontroller registers void main(void)
{
P0=(8>4)?8:4;// Send the conditional operation result to P0 port, P0=8=0000 1000B while(1)
; // Set infinite loop to prevent the program from “running away”
}
*Example 13:Use P0 port to display the result of bitwise “XOR” operation #include<reg51.h> // Include the header file for microcontroller registers void main(void)
{
P0=0xa2^0x3c;// Send the conditional operation result to P0 port, P0=8=0000 1000B while(1)
; // Set infinite loop to prevent the program from “running away”
}
*Example 16:Use P0 to display the result of left shift operation
#include<reg51.h> // Include the header file for microcontroller registers void main(void)
{
P0=0x3b<<2;// Send the left shift operation result to P0 port, P0=1110 1100B=0xec while(1)
; // Infinite loop to prevent the program from “running away”
}
*Example 17:“Universal Logic Circuit” experiment
#include<reg51.h> // Include the header file for microcontroller registers
sbit F=P1^4; // Define bit F as P1.4
sbit X=P1^5; // Define bit X as P1.5
sbit Y=P1^6; // Define bit Y as P1.6
sbit Z=P1^7; // Define bit Z as P1.7
void main(void)
{
while(1)
{
F=((~X)&Y)|Z; // Assign the logical operation result to F
;
}
}
*Example 18:Use right shift operation to light up 8 LEDs on P1 port in sequence #include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for a period of time
/
void delay(void)
{
unsigned int n;
for(n=0;n<30000;n++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char i;
while(1)
{
P1=0xff;
delay();
for(i=0;i<8;i++)// Set loop count to 8
{
P1=P1>>1; // Each loop right shifts each bit of P1, high bit fills with 0 delay(); // Call delay function
}
}
}
*Example 19:Use if statement to control the direction of 8 LEDs on P0 port #include<reg51.h> // Include the header file for microcontroller registers
sbit S1=P1^4; // Define bit S1 as P1.4
sbit S2=P1^5; // Define bit S2 as P1.5
/
Function: Main function
/
void main(void)
{
while(1)
{ if(S1==0) // If button S1 is pressed P0=0x0f; // Light up the high four LEDs on P0 if(S2==0) // If button S2 is pressed P0=0xf0; // Light up the low four LEDs on P0 }
*Example 20:Use switch statement to control the lighting state of 8 LEDs on P0 port #include<reg51.h> // Include the header file for microcontroller registers
sbit S1=P1^4; // Define bit S1 as P1.4
/
Function: Delay for a period of time
/
void delay(void)
{
unsigned int n;
for(n=0;n<10000;n++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char i;
i=0; // Initialize i to 0
while(1)
{
if(S1==0) // If S1 key is pressed
{
delay(); // Delay for a period of time
if(S1==0) // If S1 key is pressed again
i++; // Increment i by 1
if(i==9) // If i=9, reset it to 1
i=1;
}
switch(i) // Use multi-branch selection statement
{
}
} case 1: P0=0xfe; // First LED on break; case 2: P0=0xfd; // Second LED on break; case 3:P0=0xfb; // Third LED on break; case 4:P0=0xf7; // Fourth LED on break; case 5:P0=0xef; // Fifth LED on break; case 6:P0=0xdf; // Sixth LED on break; case 7:P0=0xbf; // Seventh LED on break; case 8:P0=0x7f; // Eighth LED on break; default: // Default value, turn off all LEDs P0=0xff; }
*Example 21:Use for statement to control the number of beeps from the buzzer
#include<reg51.h> // Include the header file for microcontroller registers sbit sound=P3^7; // Define bit sound as P3.7 / Function: Delay to form 1600Hz audio
/ void delay1600(void)
{
unsigned char n;
for(n=0;n<100;n++)
;
}
/ Function: Delay to form 800Hz audio
/ void delay800(void)
{
unsigned char n;
for(n=0;n<200;n++)
;
}
/ Function: Main function
/ void main(void)
{
unsigned int i;
while(1)
{
for(i=0;i<830;i++)
{
sound=0; // P3.7 outputs low level delay1600();
sound=1; // P3.7 outputs high level delay1600();
}
for(i=0;i<200;i++)
{
sound=0; // P3.7 outputs low level delay800();
sound=1; // P3.7 outputs high level delay800();
}
}
}
*Example 22:Use while statement to control LED
#include<reg51.h> // Include the header file for microcontroller registers / Function: Delay for about 60ms (3 100 200=60000μs) / void delay60ms(void)
{
unsigned char m,n;
for(m=0;m<100;m++)
for(n=0;n<200;n++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char i;
while(1) // Infinite loop
{
i=0; // Initialize i to 0
while(i<0xff) // Execute loop body while i is less than 0xff (255) {
P0=i; // Send i to P0 port for display
delay60ms(); // Delay
i++; // Increment i
}
}
}
*Example 23:Use do-while statement to control the 8 LEDs on P0 port to light up in sequence #include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for about 60ms (3 100 200=60000μs)
/
void delay60ms(void)
{
unsigned char m,n;
for(m=0;m<100;m++)
for(n=0;n<200;n++)
;
}
/
Function: Main function
/
void main(void)
{
do
{
P0=0xfe; // First LED on
delay60ms();
}
P0=0xfd; // Second LED on delay60ms(); P0=0xfb; // Third LED on delay60ms(); P0=0xf7; // Fourth LED on delay60ms(); P0=0xef; // Fifth LED on delay60ms(); P0=0xdf; // Sixth LED on delay60ms(); delay60ms(); P0=0xbf; // Seventh LED on delay60ms(); P0=0x7f; // Eighth LED on delay60ms(); }while(1); // Infinite loop, making the 8 LEDs light up in sequence
*Example 24:Use character array to control the 8 LEDs on P0 port to light up in sequence #include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for about 60ms (3 100 200=60000μs)
/
void delay60ms(void)
{
unsigned char m,n;
for(m=0;m<100;m++)
for(n=0;n<200;n++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char i;
unsigned char code Tab[ ]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f}; // Define unsigned character array
while(1)
{
for(i=0;i<8;i++)
{
P0=Tab[i];// Sequentially reference array elements and send them to P0 port for display
delay60ms();// Call delay function
}
}
}
*Example 25:Use P0 port to display string constant
#include<reg51.h> // Include the header file for microcontroller registers
/
Function: Delay for about 150ms (3 200 250=150 000μs=150ms)
/
void delay150ms(void)
{
unsigned char m,n;
for(m=0;m<200;m++)
for(n=0;n<250;n++)
;
}
/
Function: Main function
/
void main(void)
{
unsigned char str[]={