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humidity_sensor.exe.~asm
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humidity_sensor.exe.~asm
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DATA SEGMENT
; PORT ADDRESSES
PORTA EQU 00H
PORTB EQU 02H
PORTC EQU 04H
CONTROL_REG EQU 06H
; TEXT TO DISPLAY ON LCD
HUMIDITY DB "Humidity: $"
PPM DB "ppm$"
; VARIABLES TO KEEP TRACK OF PORT DATA
PORTB_VAL DB 00H
PORTC_VAL DB 00H
; MISC VARS
QUOTIENT DB 31H
REMAINDER DB 32H
DECIMAL_POINT DB '.'
MAX_PPM DB 56
ENDS
STACK SEGMENT
DW 128 DUP(0)
ENDS
CODE SEGMENT
START:
; SETTING SEGMENT REGISTERS
MOV AX, DATA
MOV DS, AX
MOV ES, AX
; INITIALISING 8255 WITH PORT-A AS INPUT PORT AND PORT-B, PORT-C AS OUTPUT PORTS
MOV AL, 10010000B
OUT CONTROL_REG, AL
CALL LCD_INIT
MOV DL, 01H
MOV DH, 01H
CALL LCD_SET_CUR
; GET DATA FROM ADC AND DISPLAY ON LCD
CALL DISPLAY_HUMIDITY
HLT
; END OF MAIN PROCEDURE
; ============= DISPLAY HUMIDITY VALUE PROCEDURE =============
PROC DISPLAY_HUMIDITY
X1:
IN AL, PORTA
MOV QUOTIENT, AL
CALL CHANGE_TO_PPM
MOV AL, 00H
OUT PORTC, AL
MOV CX, 20000
CALL DELAY
MOV AL, 01H
OUT PORTC, AL
CALL LCD_CLEAR
LEA SI, HUMIDITY
CALL LCD_PRINTSTR
MOV AH, QUOTIENT
CALL LCD_WRITE_CHAR
MOV AH, DECIMAL_POINT
CALL LCD_WRITE_CHAR
MOV AH, REMAINDER
CALL LCD_WRITE_CHAR
LEA SI, PPM
CALL LCD_PRINTSTR
MOV CX, 20000
CALL DELAY
JMP X1
RET
ENDP DISPLAY_HUMIDITY
; ============= DELAY PROCEDURE =============
PROC DELAY
; HERE CX CONTROLS THE AMOUNT OF DELAY, CX=50 MEANS A DELAY OF 1 MS.
JCXZ @DELAY_END
@DEL_LOOP:
LOOP @DEL_LOOP
@DELAY_END:
RET
ENDP DELAY
; ============= ADC VALUE CONVERSION TO PPM VALUE =============
PROC CHANGE_TO_PPM
; QUOTIENT HAS THE VALUE TO BE CONVERTED INTO PPM
; LET VALUE FROM ADC BE X
; MAX_PPM STORES THE MAXIMUM PPM TO BE SHOWN * 10
; VALUE TO BE SHOWN IN PPM = (MAX_PPM) * X / 2550
; EG. X = 255 CORRESPONDS TO MAX_PPM
; DIGIT BEFORE DECIMAL IS STORED IN QUOTIENT
; DIGIT AFTER DECIMAL IS STORED IN REMAINDER
MOV AL, QUOTIENT
MOV AH, 00H ; AX = AH:AL
MOV CL, MAX_PPM
MOV CH, 00H
MUL CX ; AX = AX * MAX_PPM
MOV BX, 2550
DIV BX ; AX = AX / 2550 AND DX = AX % 2550
; AX STORES THE QUOTIENT, DX STORES THE REMAINDER
ADD AL, 30H ; CONVERTING HEX VALUE TO ASCII
MOV QUOTIENT, AL ; STORING FIRST DECIMAL ASCII
MOV AX, DX ; REMAINDER TRANSFERRED TO AX
MOV CX, 10
MUL CX ; AX = AX * 10
DIV BX ; AX = AX / 2550
; AX STORES THE QUOTIENT, FOR THIS CASE ALL THE QUOTIENTS ARE ONLY 8 BIT SO IT IS STORED IN AL
ADD AL, 30H ; CONVERTING HEX VALUE TO ASCII
MOV REMAINDER, AL ; STORING SECOND DECIMAL ASCII
RET
ENDP CHANGE_TO_PPM
; ============= ALL LCD PROCEDURES INVOLVED =============
PROC LCD_INIT
MOV AL, 01H
CALL OUT_C ; MAKING LCD INPUT RS = RW = E = LOW (00H) AT THE START
MOV CX, 1000
CALL DELAY ; 20 MS DELAY
; RESET SEQUENCE
MOV AH, 30H
CALL LCD_CMD
MOV CX, 250
CALL DELAY ; 250 MS DELAY
MOV AH, 30H
CALL LCD_CMD
MOV CX, 50
CALL DELAY ; 1 MS DELAY
MOV AH, 30H
CALL LCD_CMD
MOV CX, 500
CALL DELAY ; 10 MS DELAY
; SET FUNCTION
MOV AH, 38H
CALL LCD_CMD
MOV AH, 0CH
CALL LCD_CMD
MOV AH, 01H
CALL LCD_CMD
MOV AH, 06H
CALL LCD_CMD
RET
ENDP LCD_INIT
PROC LCD_CMD
; AH CONTAINS THE COMMAND CODE
PUSH DX
PUSH AX
MOV AL, PORTC_VAL
AND AL, 0FDH ; RESET RS, AL = 1111 1101B, SINCE RS IS AT PIN PC1 OF 8255
CALL OUT_C
; SET OUT DATA PINS
MOV AL, AH
CALL OUT_B
MOV AL, PORTC_VAL
OR AL, 1000B ; SET E, AL = 0000 1000B, SINCE EN IS AT PIN PC3 OF 8255
CALL OUT_C
MOV CX, 50
CALL DELAY ; 1 MS DELAY
MOV AL, PORTC_VAL
AND AL, 0F7H ; RESET E, AL = 1111 0111B, SINCE E IS AT PIN PC3 OF 8255
CALL OUT_C
MOV CX, 50
CALL DELAY ; 1 MS DELAY
POP AX
POP DX
RET
ENDP LCD_CMD
PROC LCD_CLEAR
MOV AH, 01H
CALL LCD_CMD
RET
ENDP LCD_CLEAR
PROC LCD_WRITE_CHAR
; AH CONTAINS THE INFO TO DISPLAY
PUSH AX
MOV AL, PORTC_VAL
OR AL, 10B ; SET RS, AL = 0000 0010B, SINCE RS IS AT PIN PC1 OF 8255
CALL OUT_C
; SET OUT DATA PINS
MOV AL, AH
CALL OUT_B
MOV AL, PORTC_VAL
OR AL, 1000B ; SET E, AL = 0000 1000B, SINCE EN IS AT PIN PC3 OF 8255
CALL OUT_C
MOV CX, 50
CALL DELAY ; 1 MS DELAY
MOV AL, PORTC_VAL
AND AL, 0F7H ; RESET E, AL = 1111 0111B, SINCE E IS AT PIN PC3 OF 8255
CALL OUT_C
POP AX
RET
ENDP LCD_WRITE_CHAR
PROC LCD_PRINTSTR
; SI CONTAINS THE ADDRESS OF THE STRING ENDING WITH '$'
PUSH SI
PUSH AX
@LCD_PRINTSTR_LT:
LODSB
CMP AL, '$'
JE @LCD_PRINTSTR_EXIT
MOV AH, AL
CALL LCD_WRITE_CHAR
JMP @LCD_PRINTSTR_LT
@LCD_PRINTSTR_EXIT:
POP AX
POP SI
RET
ENDP LCD_PRINTSTR
PROC LCD_SET_CUR
; DH = ROW, DL = COL
PUSH AX
; LCD USES 0 INDEXING FOR COLUMNS
DEC DH
; DL = 1
MOV AH, 80H
JMP @LCD_SET_CUR_ENDCASE
@LCD_SET_CUR_ENDCASE:
ADD AH, DH
CALL LCD_CMD
POP AX
RET
ENDP LCD_SET_CUR
PROC OUT_B
; AL CONTAINS THE DATA TO OUTPUT AND THIS IS STORED IN PORTB_VAL
OUT PORTB, AL
MOV PORTB_VAL, AL
RET
ENDP OUT_B
PROC OUT_C
; AL CONTAINS THE DATA TO OUTPUT AND THIS IS STORED IN PORTC_VAL
OUT PORTC, AL
MOV PORTC_VAL, AL
RET
ENDP OUT_C
CODE ENDS
END START