4. Move the advertising light left and right

1. The experimental task 
is to move a single light left and right. The hardware circuit is shown in Figure 4.4.1. The eight light-emitting diodes L1-L8 are connected to the P1.0-P1.7 interfaces of the single-chip computer. When the output is "0", the light-emitting diodes light up. At the beginning, P1.0→P1.1→P1.2→P1.3→┅→P1.7→P1.6→┅→P1.0 lights up, and the cycle repeats. 
2. Circuit schematic diagram 
 
Figure 4.4.1  3. Hardware connection on the system board 
Connect P1.0-P1.7 in the "single-chip system" area to the L1-L8 port in the "eight-way LED indicator module" area with an 8-core cable. The requirements are: P1.0 corresponds to L1, P1.1 corresponds to L2, ..., P1.7 corresponds to L8.
4. Program design content 
We can use the output port instruction MOV P1, A or MOV P1, #DATA. As long as the accumulator value or constant value is given, and then the above instruction is executed, the output control action can be achieved.
The data sent each time is different. The specific data is shown in Table 1 below
P1.7  P1.6  P1.5  P1.4  P1.3  P1.2  P1.1  P1.0  illustrate  L8  L7  L6  L5  L4  L3  L2  L1  1 1 1 1 1 1 1 0  L1 Bright 1 1 1 1 1 1 0  1 L2 Bright 1 1 1 1 1 0  1 1 L3 Bright 1 1 1 1 0  1 1 1 L4 Bright 1 1 1 0  1 1 1 1 L5 Bright 1 1 0  1 1 1 1 1 L6 Bright 1 0  1 1 1 1 1 1 L7 Bright 0  1 1 1 1 1 1 1 L8 Bright Table 1 5.       Flowchart 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Figure 4.4.2 6. Assembly source program 
                   ORG 0 
START: MOV R2,#8 
                   MOV A,#0FEH 
                   SETB C 
LOOP: MOV P1,A 
                   LCALL DELAY 
                   RLC A 
                   DJNZ R2,LOOP 
                   MOV R2,#8 
LOOP1: MOV P1,A 
                   LCALL DELAY            
                   RRC A 
                   DJNZ R2 ,LOOP1 
                   LJMP START 
DELAY: MOV R5,#20; 
D1: MOV R6,#20 
D2: MOV R7,#248 
                   DJNZ R7,$ 
                   DJNZ R6,D2 
                   DJNZ R5,D1 
                   RET 
                   END 
7. C language source program 
#include  
unsigned char i; 
unsigned char temp; 
unsigned char a,b; 
  
void delay(void) 
{ 
  unsigned char m,n,s; 
  for(m=20;m>0;m --) 
  for(n=20;n>0;n--) 
  for(s=248;s>0;s--); 
} 
void main(void) 
{ 
  while(1) 
    { 
      temp=0xfe; 
      P1= temp; 
      delay(); 
      for(i=1;i<8;i++) 
        { 
          a=temp<           b=temp>>(8-i); 
          P1=a|b; 
          delay(); 
        } 
      for( i=1;i<8;i++) 
        { 
          a=temp>>i; 
          b=temp<<(8-i); 
          P1=a|b; 
          delay(); 
        } 
    } 
}