Advertising light design using table method

1. Experimental tasks

Let's use the table-fetching method to implement the advertising light, so that port P1 can make a single light change: move left 2 times, move right 2 times, and flash 2 times (delay time 0.2 seconds).

2. Circuit diagram

Figure 4.5.1

3. Hardware connection on the system board

Use an 8-core cable to connect P1.0-P1.7 in the "MCU System" area to the L1-L8 ports in the "Eight-way LED Indicator Module" area. The requirements are: P1.0 corresponds to L1, P1.1 corresponds to L2, ..., P1.7 corresponds to L8.

4. Programming content

When programming with a table, use the following instructions to complete

(1) Use the MOV DPTR, #DATA16 instruction to set the data pointer register to the beginning of the table.

(2) Using the instruction MOVC A, @A + DPTR, the program counter PC can be pointed to the data to be retrieved from the table based on the value of the accumulator plus the value of DPTR.

Therefore, as long as the control code is built into a table, and the MOVC function is used to perform the code retrieval operation, some complex control actions can be easily processed. The table retrieval process is shown in the figure below:

Program flowchart[page]

6. Assembly source program

                            ORG 0

START: MOV DPTR,#TABLE

LOOP: CLR A

                            MOVC A,@A+DPTR

                            CJNE A,#01H,LOOP1

                            JMP START

LOOP1: MOV P1,A

                           MOV R3,#20

                            LCALL DELAY

                            INC DPTR

                           JMP LOOP

DELAY: MOV R4,#20

D1: MOV R5,#248

                            DJNZ R5,$

                            DJNZ R4,D1

                           DJNZ R3,DELAY

                            RET

TABLE: DB 0FEH,0FDH,0FBH,0F7H

                            DB 0EFH,0DFH,0BFH,07FH

                           DB 0FEH,0FDH,0FBH,0F7H

                            DB 0EFH,0DFH,0BFH,07FH               

                           DB 07FH,0BFH,0DFH,0EFH

                            DB 0F7H,0FBH,0FDH,0FEH

                            DB 07FH,0BFH,0DFH,0EFH

                            DB 0F7H,0FBH,0FDH,0FEH

                            DB 00H, 0FFH,00H, 0FFH

                            DB 01H

                            END

7. C language source program

#include

unsigned char code table[]={0xfe,0xfd,0xfb,0xf7,

                            0xef,0xdf,0xbf,0x7f,

                            0xfe,0xfd,0xfb,0xf7,

                            0xef,0xdf,0xbf,0x7f,

                            0x7f,0xbf,0xdf,0xef,

                            0xf7,0xfb,0xfd,0xfe,

                            0x7f,0xbf,0xdf,0xef,

                            0xf7,0xfb,0xfd,0xfe,

                            0x00,0xff,0x00,0xff,

                            0x01};

unsigned char i;

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)

    {

      if(table[i]!=0x01)

        {

          P1=table[i];

          i++;

          delay();

        }

        else

          {

            i=0;

          }

    }

}

The above is the full source code of the advertising light design