Circuit Documentation

Summary

This circuit is designed to monitor soil moisture levels using multiple sensors and to control a water pump based on the sensor readings. The Arduino UNO serves as the central microcontroller, interfacing with soil moisture sensors, a temperature and humidity sensor (DHT11), an I2C LCD screen for display, and a relay to control the water pump. The system is powered by a 9V battery, and the relay switches the pump on and off as needed.

Component List

Arduino UNO

• Microcontroller board based on the ATmega328P
• It has 14 digital input/output pins, 6 analog inputs, a 16 MHz quartz crystal, a USB connection, a power jack, an ICSP header, and a reset button.

Soil Moisture Sensor (x3)

• Sensor that measures the volumetric content of water in the soil
• It has a VCC, GND, and SIG pin for power, ground, and signal output, respectively.

9V Battery

• Standard 9V battery used to provide power to the circuit.

12V Single Channel Relay

• An electromechanical switch used to control high power devices, such as the water pump.
• It has normally closed (NC), common (COM), and normally open (NO) terminals, as well as an input (IN), ground (GND), and VCC for control.

Mini Diaphragm Water Pump

• A pump used for moving water, typically controlled by a relay or a transistor.
• It has positive (+) and negative (-) terminals for power connection.

I2C LCD 16x2 Screen

• A 16x2 character LCD display that uses the I2C communication protocol.
• It has SCL and SDA pins for the I2C interface, VCC and GND for power, and additional pins for more direct control.

DHT11 Sensor V2

• A basic, ultra low-cost digital temperature and humidity sensor.
• It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and outputs a digital signal on the data pin (no analog input pins needed).

Wiring Details

Arduino UNO

• 3.3V connected to VCC of all Soil Moisture Sensors
• 5V connected to VCC of 12V Single Channel Relay, DHT11 Sensor V2, and I2C LCD 16x2 Screen
• GND connected to GND of all Soil Moisture Sensors, 12V Single Channel Relay, DHT11 Sensor V2, and I2C LCD 16x2 Screen
• A0 connected to SIG of the first Soil Moisture Sensor
• A1 connected to SIG of the second Soil Moisture Sensor
• A2 connected to SIG of the third Soil Moisture Sensor
• A4 (SDA) connected to SDA of I2C LCD 16x2 Screen
• A5 (SCL) connected to SCL of I2C LCD 16x2 Screen
• D7 connected to DAT of DHT11 Sensor V2
• D8 connected to IN of 12V Single Channel Relay

Soil Moisture Sensors

• VCC connected to 3.3V on Arduino UNO
• GND connected to GND on Arduino UNO
• SIG connected to A0, A1, and A2 on Arduino UNO (one sensor per pin)

9V Battery

• - connected to Negative (-) of Mini Diaphragm Water Pump
• + connected to COM of 12V Single Channel Relay

12V Single Channel Relay

• VCC connected to 5V on Arduino UNO
• GND connected to GND on Arduino UNO
• IN connected to D8 on Arduino UNO
• COM connected to + of 9V Battery
• NO connected to Positive (+) of Mini Diaphragm Water Pump

Mini Diaphragm Water Pump

• Positive (+) connected to NO of 12V Single Channel Relay
• Negative (-) connected to - of 9V Battery

I2C LCD 16x2 Screen

• SDA connected to A4 (SDA) on Arduino UNO
• SCL connected to A5 (SCL) on Arduino UNO
• VCC (5V) connected to 5V on Arduino UNO
• GND connected to GND on Arduino UNO

DHT11 Sensor V2

• DAT connected to D7 on Arduino UNO
• VCC connected to 5V on Arduino UNO
• GND connected to GND on Arduino UNO

Documented Code

Arduino UNO Code (sketch.ino)

void setup() {
  // put your setup code here, to run once:

}

void loop() {
  // put your main code here, to run repeatedly:

}

Note: The provided code is a template and does not contain any functional code. It needs to be filled in with the logic for reading sensors, controlling the relay, and updating the display.