4.2. Controlling Rotation of LED Serially - RS232 Serial

Standart communication using serial data RS232 is very efective way to minimize cable connection. This experiment will be done to arrange the rotation direction of LED by using DELPHI Programming and conducted serially.

Figure 4.1. Sending Command to LED

Step 1st
Build the circuit as shown in figure 4.1. As you seen on figure 4.1. Remember, that all we want to do with this lesson is send data out trough PC serially, to direct LED rotation.

Step 2nd
In this step, you must tipe the assembly program to make your serial working, we assume that you have already known the editor, we used MIDE-51 to edit the program. ( Download File asm and hex : rotateRL.zip, Download Complete Circuit File : SerialLED.PDF )

     org 0h
     nop
     call initserial
gets:call inchar
     cjne a,#1,rotR
     sjmp rotL
     sjmp gets
     ;
rotR:mov P2,#11111110b; 
     call delay
     mov P2,#11111101b; 
     call delay       ; 
     mov P2,#11111011b; 
     call delay       ; 
     mov P2,#11110111b; 
     call delay       ; 
     mov P2,#11101111b; 
     call delay       ; 
     mov P2,#11011111b; 
     call delay       ; 
     mov P2,#10111111b; 
     call delay       ; 
     mov P2,#01111111b; 
     call delay       ; 
     sjmp gets
;
rotL:mov P2,#01111111b; 
     call delay
     mov P2,#10111111b; 
     call delay       ; 
     mov P2,#11011111b; 
     call delay       ; 
     mov P2,#11101111b; 
     call delay       ; 
     mov P2,#11110111b; 
     call delay       ; 
     mov P2,#11111011b; 
     call delay       ; 
     mov P2,#11111101b; 
     call delay       ; 
     mov P2,#11111110b; 
     call delay       ; 
     sjmp gets
;
initserial:
        mov scon,#52h ;serial mode 1 configuration
        mov tmod,#20h ; Baud rate 2400 BPS
        mov th1,#-13
        setb tr1
        ret
;
inchar:
        detect: jnb ri,detect;detecting do data have been accepted or not yet.
        clr ri
        mov a,sbuf
        ret
;

delay:
      	MOV	R7,#00H
again2:	MOV	R6,#00H
again1:	MOV	R5,#00H
again:	INC	R5
      	CJNE	R5,#50H,again
      	INC	R6
      	CJNE	R6,#50H,again1
      	INC	R7
      	CJNE	R7,#50H,again2
      	RET

;
End

To get the data from microcontroller serially, computer must run the program to get data from port communication RS232, in this experiment I have been used Delphi programming: ( Download File Delphi : rotateLED.zip )

(a)

(b)
Figure 4.2. Delphi Programming for Left or Right Rotate

var
  Form1: TForm1;
  data,status:byte;
const
    base = $3f8;{base address port serial}
    lcr = 3; {line control register}
    dll = 0; {divisor lacht low byte}
    dlh = 1; {divisor lacht high byte}
    lsr = 5; {line status register}

Procedure Initserial;
begin
    asm
        mov dx,base+lcr; {address line control register}
        mov al,$80 ; {10000000b = access bit divisor lacht}
        out dx,al
;
        mov dx,base+dll; {address divisor lacht low byte}
        mov al,$30 ; {DLLB = 30h}
        out dx,al
;
        mov dx,base+dlh; {address divisor lacht high byte}
        mov al,$00     ; {DLLH = 00h}
        out dx,al
;                       {In this case Port Serial have}
;                       { baud rate = 2400 bps}
        mov dx,base+lcr;{address line control register}
        mov al,$03 ;    {00000011b =}
        out dx,al ;     {bit 7=0, access to Rx buffer & Tx
;                       {bit 6=0, set break disable
;                       {bit 5-4-3=000, no parity
;                       {bit 2=0, one stop bit
;                       {bit 1-0=11,data lenght 8 bit}
        end;
end;

Procedure Send_Data_Serial;
begin
    asm
        mov dx,base
        mov al,data
        out dx,al
    end
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Initserial;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
repeat
  asm
   mov dx,base+lsr ; {address line status register }
   in al,dx
   and al,$20      ; {00100000b =not masking bit 5}
   mov status,al   ; {bit5=Empty Transmitting holding reg}
  end;
until status = $20; { If ETHR = 1 then data ready tobe send }
data:=0;
Send_Data_Serial;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
 repeat
  asm
   mov dx,base+lsr; {address line status register }
   in al,dx
   and al,$20     ; {00100000b =not masking bit 5}
   mov status,al  ; {bit5=Empty Transmitting holding reg}
  end;
until status = $20; { If ETHR = 1 then data ready tobe send}
data:=1;
Send_Data_Serial;
end;

Step 3rd
Safe your assembly program above, Compile the program that you have been save by using MIDE-51, see the software instruction.

Step 4th
Download your hex file (rotateRL.hex ) into the microcontroller by using Microcontroller ATMEL ISP software, see the instruction.After download this hex file you'll see the action of serial transmition( of course if your cable connection and your program are corrected ).

BACK NEXT

Lesson 1:
T o o l
1.1. Programmer
1.2. Edsim 51
1.3. MIDE-51
1.4. ATMEL ISP

Lesson 2:
Input Output
2.1.LED
2.2.Swicht
2.3.7 Segmen
2.4.LCD Character
2.5.ADC
2.6.DAC
2.7.Motor Stepper
2.8.Keypad

Lesson 3:
Timer Counter
3.1.Basic
3.2.Mode 0
3.3.Mode 1
3.4.Mode 2
3.5.Mode 3

Lesson 4:
Serial Comm.
4.1.Basic
4.2.LED
4.3.Rotate LED
4.2 ADC
4.3.LCD

Lesson 5:
Interuption
5.1.Basic
5.2.Timer
5.2.External