Circuit Documentation

Summary

This circuit is designed to control a 5V mini water pump and monitor soil moisture levels using an Arduino Nano as the central microcontroller. The circuit includes a 12V relay to switch the water pump, a capacitive soil moisture sensor for detecting moisture levels, an OLED display for output, and various other components such as resistors, a transistor, a diode, and capacitors for power stabilization and signal interfacing.

Component List

Arduino Nano

• Microcontroller board based on the ATmega328P
• It has a variety of digital and analog I/O pins.

Electrolytic Capacitor

• Capacitance: 47 µF (microfarads)
• Used for power supply filtering.

Power Jack

• Connects the external power supply to the circuit.

2.1mm DC Barrel Jack

• Used to connect an external power source with a barrel connector.

12V Relay

• Electromechanical switch used to control the water pump.

0.96" OLED

• Small display for showing information such as soil moisture levels.

Resistor (1 kΩ)

• Two resistors with a resistance of 1 kΩ each, used for current limiting and voltage division.

BC547

• NPN Bipolar Junction Transistor (BJT) used for signal amplification or switching.

1N4007 Rectifier Diode

• Standard diode used for protecting the circuit from reverse voltage.

Capacitive Soil Moisture Sensor V1.2

• Measures the moisture content in the soil.

LED: Two Pin (blue)

• Blue light-emitting diode used as an indicator.

5V Mini Water Pump

• A small pump for moving water, controlled by the relay.

12V Power Supply

• Provides the necessary power for the circuit.

Wiring Details

Arduino Nano

• GND connected to the common ground net.
• 5V connected to the OLED VDD, relay VCC, and soil moisture sensor VCC.
• VIN connected to the positive side of the electrolytic capacitor and the center pin of the DC barrel jack.
• A0 connected to the AOUT pin of the soil moisture sensor.
• A4 connected to the SDA pin of the OLED.
• A5 connected to the SCK pin of the OLED.
• D4 connected to one end of a 1 kΩ resistor.

Electrolytic Capacitor

• - (negative) connected to the common ground net.
• + (positive) connected to the Arduino Nano VIN.

Power Jack

• POSITIF connected to the positive terminal of the 12V power supply.
• NEGATIF connected to the negative terminal of the 12V power supply.

2.1mm DC Barrel Jack

• switch connected to the common ground net.
• center connected to the positive side of the electrolytic capacitor and Arduino Nano VIN.

12V Relay

• + connected to the OLED VDD and Arduino Nano 5V.
• - connected to the collector of the BC547 transistor and the anode of the 1N4007 diode.
• C connected to the positive pin of the water pump.
• NC connected to the OLED VDD and Arduino Nano 5V.
• NO not connected in this circuit.

0.96" OLED

• GND connected to the common ground net.
• VDD connected to the Arduino Nano 5V, relay VCC, and soil moisture sensor VCC.
• SCK connected to the Arduino Nano A5.
• SDA connected to the Arduino Nano A4.

Resistor (1 kΩ)

• One resistor connected between Arduino Nano D4 and the base of the BC547 transistor.
• The other resistor connected between the anode of the LED and the common ground net.

BC547

• collector connected to the relay - and the cathode of the 1N4007 diode.
• base connected to one end of a 1 kΩ resistor.
• Emitter connected to the common ground net.

1N4007 Rectifier Diode

• Cathode connected to the OLED VDD and relay VCC.
• Anode connected to the collector of the BC547 transistor.

Capacitive Soil Moisture Sensor V1.2

• GND connected to the common ground net.
• VCC connected to the OLED VDD and Arduino Nano 5V.
• AOUT connected to the Arduino Nano A0.

LED: Two Pin (blue)

• cathode connected to the common ground net.
• anode connected to one end of a 1 kΩ resistor.

5V Mini Water Pump

• positive pin connected to the relay C.
• negative pin connected to the common ground net.

12V Power Supply

• + connected to the power jack POSITIF.
• - connected to the power jack NEGATIF.

Documented Code

Arduino Nano - sketch.ino

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

}

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

}

Arduino Nano - documentation.txt

(No additional documentation provided for the code)

(Note: The code provided is a template and does not contain any functional code. It will need to be populated with the logic required to read the soil moisture sensor, control the OLED display, and manage the water pump via the relay.)