Notes

ORG 0000H
SJMP MAIN ; Jump to main program

ORG 0030H
ADC_DATA EQU 30H ; Define ADC_DATA memory location

MAIN:
CALL INIT_SERIAL ; Initialize serial communication
CALL LCD_INITIALISE ; Initialize LCD

SETB P0.0 ; RELAY ON
CLR P0.1 ; BUZZER ON
CALL LCD_LOADING ; Display loading message

MOV P2, #0FFH ; Set P2 as input for ADC
CALL LCD_DISPLAY_INIT ; Display "GAS:000PPM R:OFF"

CLR P0.1 ; BUZZER OFF
CALL DELAY_500MS ; Initial delay

LOOP:
CALL ADC_READ ; Read ADC value
MOV A, ADC_DATA ; Move ADC data to A
CALL LCD_UPDATE ; Update LCD display

MOV B, #80
CJNE A, B, CHECK_SAFE
SJMP ALERT

CHECK_SAFE:
JC SAFE ; If A < 80, jump to SAFE state
SJMP ALERT ; Otherwise, go to ALERT

SAFE:
CALL SAFE_STATE ; If gas is normal, keep relay ON
SJMP LOOP ; Repeat process

;------------------------------------------------
; ADC READ FUNCTION
;------------------------------------------------
ADC_READ:
CLR P0.6 ; WR = 0 (Start conversion)
SETB P0.6 ; WR = 1 (End conversion)

WAIT_INTR:
JNB P0.5, WAIT_INTR ; Wait until INTR = 0 (conversion complete)

CLR P0.7 ; RD = 0 (Read ADC Data)
MOV ADC_DATA, P2 ; Store ADC Data
SETB P0.7 ; RD = 1 (Stop read)
RET

;------------------------------------------------
; LCD DISPLAY UPDATE
;------------------------------------------------
LCD_UPDATE:
CALL LCD_CMD ; Ensure cursor is set
MOV A, ADC_DATA
CALL LCD_WRITE_DIGITS ; Convert and write to LCD
RET

;------------------------------------------------
; ALERT FUNCTION
;------------------------------------------------
ALERT:
CLR P0.0 ; RELAY OFF
CLR P0.1 ; BUZZER ON
CALL LCD_ALERT_MSG ; Display "G:HIGH V:CLOSE"
CALL SEND_SMS ; Send SMS Alert
SJMP LOOP
RET

;------------------------------------------------
; SAFE STATE FUNCTION
;------------------------------------------------
SAFE_STATE:
SETB P0.0 ; RELAY ON
SETB P0.1 ; BUZZER OFF
CALL LCD_SAFE_MSG ; Display "G:NORMAL V:OPEN"
RET

;------------------------------------------------
; SEND SMS FUNCTION (Basic GSM Module Commands)
;------------------------------------------------
SEND_SMS:
MOV DPTR, #MSG
CALL SEND_STRING ; Send the SMS message string
RET

SEND_STRING:
CLR A
SEND_LOOP:
MOVC A, @A+DPTR ; Load character from memory
JZ END_STRING ; If NULL terminator, exit
CALL SEND_CHAR ; Send character via serial
INC DPTR
SJMP SEND_LOOP

END_STRING:
RET

MSG:
DB "VOLVE CLOSED AND POWER DISCONNECTED DUE TO GAS LEAKAGE!", 0

;------------------------------------------------
; LCD FUNCTION PROTOTYPES
;------------------------------------------------
LCD_INITIALISE:
; LCD Initialization Code
RET

LCD_LOADING:
; Display "LOADING...."
RET

LCD_DISPLAY_INIT:
; Display "GAS:000PPM R:OFF"
RET

LCD_CMD:
; LCD Command Function (Set cursor position)
RET

LCD_WRITE_DIGITS:
; Convert ADC Data to ASCII and display on LCD
RET

LCD_ALERT_MSG:
; Display "G:HIGH V:CLOSE"
RET

LCD_SAFE_MSG:
; Display "G:NORMAL V:OPEN"
RET

;------------------------------------------------
; DELAY FUNCTION (500ms)
;------------------------------------------------
DELAY_500MS:
MOV R0, #200
DELAY1:
MOV R1, #255
DELAY2:
DJNZ R1, DELAY2
DJNZ R0, DELAY1
RET

END