Xiaobai self-study c51 notes - running water lamp

Development board schematic diagram:

From the schematic diagram of the development board, we know that LEDs 1 to 8 are connected to P2＾0 to P2＾7 respectively. When low voltage is input to P2 port, the LED lights up (VCC indicates high voltage, and P2 outputs low voltage when it is 0 and high voltage when it is 1).

It can be expressed in two ways:

1.

#include

sbit led1=P2^0; //If you want to use other LEDs, change to the corresponding

void main()

{

led1=0;

}

#include

#define led P2 //no semicolon

void main()

{

led=0x00; //0x means hexadecimal, other explanations are below

}

Note: P is capitalized.

Here is the code I wrote:

#include "reg52.h "

#include "intrins.h"

#define led P2 //#define is a macro definition

void delay(unsigned int i) //custom delay function

{

while(i--);

}

void main()

{

unsigned int i=0;       //define unsigned integer i and assign value 0

led=0xfe;               //0xfe is hexadecimal: 1111 1110; that is, only the first LED is lit

delay(20000); //Call the delay function above to achieve the purpose of delay

while(i<7) //while loop, when i does not meet the condition, {} the inner loop ends

{

led=_crol_(led,1); //Left shift function: LED is shifted left by 1 bit, that is, 1111 1101, which can light up the second LED

delay(20000);

i++; //i=i+1;

} //The above while loop can make the eight LEDs light up in sequence

while(i>2)

{

led=0x55; //0101 0101

delay(5000);

led=~led; //negate: 1010 1010

delay(5000);

i--;

}

}

Next, Xiaobai self-studies C51's mood chapter:

So damn excited, just a little bit away from ascending to heaven