This document describes a breathalyzer door lock system that uses a PIC microcontroller. It checks the breath alcohol content (BAC) level using a gas sensor, and prevents the door from opening if the person is intoxicated. It also includes an keypad for administrative access. The system is intended to prevent drunken driving by not allowing intoxicated people to leave in a vehicle. It provides details on the components, including the microcontroller, gas sensor, keypad, LCD display, DC motor and more. Circuit diagrams and block diagrams are also included to explain how it works.

1. BREATHALYZER
DOOR LOCK

2. INSPIRATION
WE FOCUS NOT TO PREVENT PEOPLE FROM USING ALCOHOL
BUT PREVENT THEM FROM DRUNKEN DRIVING

3. BREATHALYZER DOOR LOCK PROVIDES
IT CHECKS THE BAC LEVEL OF THE BLOWER
IT PREVENTS THE DOOR OPENING WHENEVER
THE PERSON IS TOXICATED
IT ALSO PROVIDES ADMISTRATIVE ACCESS
WITH A KEYPAD
IT ALSO DISPLAYS THE BAC VALUE

4. BLOCK DIAGRAM

5. BLOCK DIAGRAM DESCRIPTION
1.PIC MC-16F877A
• MASTER BRAIN OF THE DEVICE
2.GAS SENSOR
• DETECTS THE BAC LEVEL OF THE BLOWER
3.KEYPAD
• FOR SELECTING MODE AND ENTERING ACCESS CODE
4.LCD DISPLAY
• DISPLAYS THE BAC VALUE AND INSTRUCTIONS
5.DC MOTOR
• CONTROLS THE OPENING OF THE DOOR

6. FEATURES OF PIC-16F877A
 High performance RISC CPU
 Only 35 single word instructions to learn
 Interrupt capability (up to 14 sources)
 Eight level deep hardware stack
 Direct, indirect and relative addressing modes
 Timer0: 8-bit timer/counter
 Timer1: 16-bit timer/counter
 Timer2: 8-bit timer/counter
 Two Capture, Compare, PWM modules
 10-bit multi-channel Analog-to-Digital converter
 Synchronous Serial Port (SSP)
 Universal Synchronous Asynchronous Receiver
Transmitter (USART/SCI)
 Parallel Slave Port (PSP)

7. CIRCUIT DIAGRAM
Vcc(9v)

8. LCD DISPLAY UNIT
•IT DISPAYS THE BAC VALUE DETECTED BY GAS SENSOR AND
ADC
•IT ALSO DISPLAYS BASIC INSTRUCTIONS

9. KEYPAD
• IT IS A PUSH TYPE 12 BUTTON KEYPAD
• USED FOR SELECTING MODE AND ENTESING
ACCESS CODE
DC MOTOR
• DC MOTOR IS USED FOR CONTROLING
OPENING OF DOOR
BUZZER
• PRODUCING CAUTION TONE WHEN TEST
FAILS AND INCORRECT PASSWORD IS
ENTERED

10. INTERNAL DIAGRAM OF GAS
SENSOR MQ-303A
STANDARD CIRCUIT
CONFIGURATION

11. FEATURES OF GAS SENSOR
• High sensitivity
•Low power consumption
•Miniature-size
• The change of the sensor resistance (RS) is obtained as the
change of the output voltage
•Generally, the sensor enters into normal working conditions
after several minutes’ preheating
• TheMQ-303A is a tin dioxide
semiconductor alcohol sensor WITH
QUICK RESPONSE SPEED .

12. DATAFLOW DIAGRAM

13. APPLICATION
1.PREVENTING DRUNKEN DRIVING AND THERE BY
REDUCING ROAD ACCIDENTS UP TO AN EXTENT
2.IN CASE OF FAILURE OF SENSOR,WE CAN
DEPEND ANOTHER ACCESSING MODE
3.CAN BE SIMPLY IMPLEMENTED ON ANY KIND OF
DOOR SYSTEM

14. THANKS
We are thankful for the Co-operation and Kindness Of the
Staff Of Electronics & Communication Dept. for
boosting our Spirit by Giving Us Innovative Suggestions
for the Successful Completion Of our Project Entitled
“BREATHALYZER DOOR lOCK” on time.