π¦ Traffic Monitoring System Circuit Diagram
π Complete Wiring Table
| Component |
Component Pin |
NodeMCU Pin |
GPIO |
Wire Color |
| DHT11 Sensor |
VCC |
3V3 |
- |
Red |
| DHT11 Sensor |
GND |
GND |
- |
Black |
| DHT11 Sensor |
DATA |
D7 |
GPIO13 |
Yellow |
| Buzzer |
Positive |
D4 |
GPIO2 |
Orange |
| Buzzer |
Negative |
GND |
- |
Black |
| Gas Sensor |
VCC |
3V3 |
- |
Red |
| Gas Sensor |
GND |
GND |
- |
Black |
| Gas Sensor |
DOUT |
D6 |
GPIO12 |
Green |
| Sound Sensor |
VCC |
3V3 |
- |
Red |
| Sound Sensor |
GND |
GND |
- |
Black |
| Sound Sensor |
DOUT |
D5 |
GPIO14 |
Blue |
| Red LED |
Anode (+) |
D0 |
GPIO16 |
Red |
| Red LED |
Cathode (-) |
GND (via 220Ξ©) |
- |
Black |
| Yellow LED |
Anode (+) |
D1 |
GPIO5 |
Yellow |
| Yellow LED |
Cathode (-) |
GND (via 220Ξ©) |
- |
Black |
| Green LED |
Anode (+) |
D2 |
GPIO4 |
Green |
| Green LED |
Cathode (-) |
GND (via 220Ξ©) |
- |
Black |
π ASCII Circuit Diagram
NodeMCU ESP8266 Breadboard Layout
βββββββββββββββββββ ββββββββββββββββββββββββββ
β βββββββ β β + + + + + + + + + + + β
β β USB β β β - - - - - - - - - - - β
β βββββββ β β β
β β β βββββ βββββ β
β 3V3 βββββββββββββΌββββββββββββββββββΌβββ€DHTβββββββ€GASβββββββββ€
β GND βββββββββββββΌββββββββββββββββββΌβββββββ βββββ β
β β β β
β D0 βββββββββββββΌββββββββββββββββββΌββ[220Ξ©]βββ€>βββ(RED) β
β D1 βββββββββββββΌββββββββββββββββββΌββ[220Ξ©]βββ€>βββ(YEL) β
β D2 βββββββββββββΌββββββββββββββββββΌββ[220Ξ©]βββ€>βββ(GRN) β
β β β β
β D4 βββββββββββββΌββββββββββββββββββΌβββͺ BUZZER β
β D5 βββββββββββββΌββββββββββββββββββΌβββββββββ β
β D6 βββββββββββββΌββββββββββββββββββΌβββ€SOUNDβββββββββββββββββ€
β D7 βββββββββββββΌββββββββββββββββββΌβββββββββ β
β β β β
βββββββββββββββββββ ββββββββββββββββββββββββββ
Power Distribution:
ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
β 3V3 Rail (Red) β
β βββ DHT11 VCC β
β βββ Gas Sensor VCC β
β βββ Sound Sensor VCC β
β β
β GND Rail (Black) β
β βββ DHT11 GND β
β βββ Gas Sensor GND β
β βββ Sound Sensor GND β
β βββ Buzzer GND β
β βββ Red LED Cathode (via 220Ξ© resistor) β
β βββ Yellow LED Cathode (via 220Ξ© resistor) β
β βββ Green LED Cathode (via 220Ξ© resistor) β
ββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββββ
π¨ Breadboard Layout Guide
Power Rails Setup:
β’ Connect NodeMCU 3V3 to positive power rail (red stripe)
β’ Connect NodeMCU GND to negative power rail (blue/black stripe)
Component Placement (Left to Right):
Row 1-5: DHT11 Temperature & Humidity Sensor
Row 10-15: MQ-2 Gas Sensor
Row 20-25: Sound Detection Sensor
Row 30-35: Traffic Light LEDs (Red, Yellow, Green)
Row 40-45: Buzzer
Row 50-55: Current Limiting Resistors (220Ξ© x 3)
β‘ Pin Configuration Summary
Input Sensors
D7 (GPIO13) - DHT11 Data Pin
D6 (GPIO12) - Gas Sensor Digital Out
D5 (GPIO14) - Sound Sensor Digital Out
Output Devices
D0 (GPIO16) - Red LED
D1 (GPIO5) - Yellow LED
D2 (GPIO4) - Green LED
D4 (GPIO2) - Buzzer
β οΈ Important Notes:
β’ Use 220Ξ© resistors for each LED to prevent burnout
β’ Ensure proper polarity for LEDs (longer leg = positive)
β’ DHT11 may need a 10kΞ© pull-up resistor on data line
β’ Double-check all connections before powering on
β’ Gas sensor needs 24-48 hours warm-up time for accurate readings
π§ Assembly Steps
- Power Setup: Connect 3V3 and GND rails on breadboard
- Sensors: Place DHT11, Gas sensor, and Sound sensor
- LEDs: Insert LEDs with 220Ξ© resistors in series
- Buzzer: Connect buzzer with proper polarity
- Wiring: Use jumper wires as per the table above
- Testing: Upload code and test each component individually