Experiment 6 -- Interface of the 8088 MPU with the 8259A PIC and LCD Module

In this week, I have done the experiment 6. This lab is to study the interfacing of the 8259A PIC with the 8088 MPU and the interfacing of the LCD module with the 8088 MPU. I need to Wrap wire the control signals of the 8259A and LCD module as shown in the lab manual, modify the I/O address field of the given test program to match our design of address decoder. Finally I need to write my own program to fulfill the following function, the switch button is pressed, my name and ID will display on the LCD.  When the button is pressed again, my partner’s name and ID will display on the LCD.

I need to according to the above figure to wrap wire, The typical one is pin7-14 of Character LCD are connected to AD0~AD7.  The pin 6 of character LCD is connected to GAL  pin17 which I have modified the address decoder  for selecting the character LCD.

For writing this assembly program, I need to initialize all the devices first. I write to loop function which can display the name of my partner and I sequentially.

     

loop1: check2: call check_key1         jnc check2         mov      dx,lcd_base         call TURN_LED1_ON         call display1         mov cx,50         call delay_X         check: call check_key1         jnc check         mov      dx,lcd_base         call TURN_LED2_ON             call display2          mov cx,50         call delay_X            jmp loop1

Also I have to write the display string function, which can display name on the LCD display.

outs1 db 'Cheng Ka Kui',0dh         outs2 db '1155003893',0dh         outs3 db 'Tai Pit Tat',0dh         outs4 db '1155023064',0dh                                     display1   PROC      NEAR         mov      dx,lcd_base busy7:     in         al,dx         and       al,10000000b         jnz        busy7         mov      al,00000001b    ;clear screen         out        dx,al ;display string1         mov      dx,lcd_base busy10:   in         al,dx         and       al,10000000b         jnz        busy10         mov      al,10000000b    ;set display address to 0         out        dx,al         mov      bx, offset outs1         call        print_string ;display string2                        mov      dx,lcd_base busy20:   in         al,dx         and       al,10000000b         jnz        busy20         mov      al,11000000b    ;set display address to 0         out        dx,al         mov      bx, offset outs2         call        print_string         ret display1   ENDP display2   PROC      NEAR         mov      dx,lcd_base busy72:   in         al,dx         and       al,10000000b         jnz        busy72         mov      al,00000001b    ;clear screen         out        dx,al ;display string3         mov      dx,lcd_base busy12:   in         al,dx         and       al,10000000b         jnz        busy12         mov      al,10000000b    ;set display address to 0         out        dx,al         mov      bx, offset outs3         call        print_string ;display string4                        mov      dx,lcd_base busy22:   in         al,dx         and       al,10000000b         jnz        busy22         mov      al,11000000b    ;set display address to 0         out        dx,al         mov      bx, offset outs4         call        print_string         ret display2   ENDP

Here is the result of our lab.

              

            

              After doing this lab, I have learnt how to write the assembly program. This is a very interesting lab. I can wrap wire to connect the device and write our own program. When the LCD can display the name and ID successfully, we felt a great sense of achievement.