Analyser circuir BREATHANALYSER

BREATHALYSER CIRCUIT IMPLEMENTED USING MICROCONTROLLERSSOR 8051

This is abreath analyser using 8051 micro controller which gives output through blood alcohol content as input.This is a BaC displayes a 3digit 7 segment display.

we need a AT89S51 microcontroller of 8051

2.alcohol sensor  MQ135

MQ135 is agas sensor it detects the presence of alcohol in blood and output is displayed.Generally MQ135 sensor detect ammonia,co2,AL2o3,alcohol9(ch3cooh),smoke,nitrogen dioxide.

this ssensor has steel net and heating element present inside.

When alcohol is present in breath is oxidised to acetic acid when touches the heating element when this acetic acid fall on sensing layer resistance  of the material decreases and bridge circuit converts to appropriate voltage.

we can use the load upto 50k

program

ORG 00H
MOV P1,#11111111B
MOV P0,#00000000B
MOV P3,#00000000B
MOV DPTR,#LUT
MAIN: MOV R4,#250D
      CLR P3.7
      SETB P3.6
      CLR P3.5
      SETB P3.5
WAIT: JB P3.4,WAIT
      CLR P3.7
      CLR P3.6
      MOV A,P1
      MOV R5,A
      SUBB A,#86
      JC NEXT
      SETB P3.3
      CLR PSW.7
NEXT: MOV A,R5
      SUBB A,#115D
      JNC LABEL
      MOV A,#00000000B
      CLR PSW.7
LABEL: MOV B,#5D
       MUL AB
       MOV B,#8D
       DIV AB
       MOV B,#10D
       DIV AB
       MOV R6,A
       MOV R7,B
DLOOP:SETB P3.0
      MOV P0,#01000000B
      ACALL DELAY
      CLR P3.0
      SETB P3.1
      MOV A,R6
      ACALL DISPLAY
      MOV P0,A
      ACALL DELAY
      CLR P3.1
      SETB P3.2
      MOV A,R7
      ACALL DISPLAY
      MOV P0,A
      ACALL DELAY
      CLR P3.2
      DJNZ R4,DLOOP
      SJMP MAIN
DELAY: MOV R3,#255D
LABEL1: DJNZ R3,LABEL1
        RET
DISPLAY: MOVC A,@A+DPTR
         CPL A
         RET
LUT: DB 3FH
     DB 06H
     DB 5BH
     DB 4FH
     DB 66H
     DB 6DH
     DB 7DH
     DB 07H
     DB 7FH
     DB 6FH

     End

MQ135 sensor require 5min  to heat 

when alcohol test done if result is true we should take some time to do another test

intefacing 7segment display with 8051 to be done carefully