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
