Circuit Documentation

Summary

This circuit is designed to read values from an NPK Soil Sensor using RS485 communication and a Capacitive Soil Moisture Sensor. The sensor values for Nitrogen, Phosphorous, and Potassium are read and printed to the Serial Monitor. The RS485 module is connected to the Arduino UNO. The moisture value is read from the Capacitive Soil Moisture Sensor and printed to the Serial Monitor.

Component List

1. Arduino UNO

   • Description: A microcontroller board based on the ATmega328P.
   • Pins: UNUSED, IOREF, Reset, 3.3V, 5V, GND, Vin, A0, A1, A2, A3, A4, A5, SCL, SDA, AREF, D13, D12, D11, D10, D9, D8, D7, D6, D5, D4, D3, D2, D1, D0

2. NPK Soil Sensor

   • Description: A sensor used to measure the Nitrogen, Phosphorous, and Potassium levels in the soil.
   • Pins: VCC, GND, A, B

3. Lipo Battery 2200mAH 30c

   • Description: A rechargeable lithium polymer battery.
   • Pins: VCC, GND

4. RS485

   • Description: A module used for RS485 communication.
   • Pins: VCC, RO, RE, GND, B, A, DE, DI

5. Capacitive Soil Moisture Sensor V1.2

   • Description: A sensor used to measure soil moisture levels.
   • Pins: GND, VCC, AOUT

6. LDR

   • Description: A light-dependent resistor used to measure light intensity.
   • Pins: A0, D0, GND, VCC

Wiring Details

Arduino UNO

• GND is connected to:

  • RS485 GND
  • Capacitive Soil Moisture Sensor V1.2 GND

• 5V is connected to:

  • RS485 VCC
  • Capacitive Soil Moisture Sensor V1.2 VCC

• A0 is connected to:

  • Capacitive Soil Moisture Sensor V1.2 AOUT

• D8 is connected to:

  • RS485 RE

• D7 is connected to:

  • RS485 DE

• D3 is connected to:

  • RS485 DI

• D2 is connected to:

  • RS485 RO

NPK Soil Sensor

• VCC is connected to:

  • Lipo Battery 2200mAH 30c VCC

• GND is connected to:

  • Lipo Battery 2200mAH 30c GND

• A is connected to:

  • RS485 A

• B is connected to:

  • RS485 B

Lipo Battery 2200mAH 30c

• VCC is connected to:

  • NPK Soil Sensor VCC

• GND is connected to:

  • NPK Soil Sensor GND

RS485

• GND is connected to:

  • Arduino UNO GND

• VCC is connected to:

  • Arduino UNO 5V

• RE is connected to:

  • Arduino UNO D8

• DE is connected to:

  • Arduino UNO D7

• DI is connected to:

  • Arduino UNO D3

• RO is connected to:

  • Arduino UNO D2

• A is connected to:

  • NPK Soil Sensor A

• B is connected to:

  • NPK Soil Sensor B

Capacitive Soil Moisture Sensor V1.2

• GND is connected to:

  • Arduino UNO GND

• VCC is connected to:

  • Arduino UNO 5V

• AOUT is connected to:

  • Arduino UNO A0

Code Documentation

#include "SoftwareSerial.h"
#include "Wire.h"

/*
 * This Arduino Sketch reads values from an NPK Soil Sensor using RS485
 * communication and a Capacitive Soil Moisture Sensor. The sensor values for
 * Nitrogen, Phosphorous, and Potassium are read and printed to the Serial
 * Monitor. The RS485 module is connected to the Arduino UNO. The moisture
 * value is read from the Capacitive Soil Moisture Sensor and printed to the
 * Serial Monitor.
 */

#define RE 8
#define DE 7
#define MOISTURE_PIN A0

const byte nitro[] = {0x01, 0x03, 0x00, 0x1e, 0x00, 0x01, 0xe4, 0x0c};
const byte phos[] = {0x01, 0x03, 0x00, 0x1f, 0x00, 0x01, 0xb5, 0xcc};
const byte pota[] = {0x01, 0x03, 0x00, 0x20, 0x00, 0x01, 0x85, 0xc0};

byte values[11];
SoftwareSerial mod(2, 3);

void setup() {
  Serial.begin(9600);
  mod.begin(9600);
  pinMode(RE, OUTPUT);
  pinMode(DE, OUTPUT);
  delay(500);
}

void loop() {
  byte val1, val2, val3;
  val1 = nitrogen();
  delay(250);
  val2 = phosphorous();
  delay(250);
  val3 = potassium();
  delay(250);
  int moisture = analogRead(MOISTURE_PIN);

  Serial.print("Nitrogen: ");
  Serial.print(val1);
  Serial.println(" mg/kg");
  Serial.print("Phosphorous: ");
  Serial.print(val2);
  Serial.println(" mg/kg");
  Serial.print("Potassium: ");
  Serial.print(val3);
  Serial.println(" mg/kg");
  Serial.print("Moisture: ");
  Serial.println(moisture);
  delay(2000);
}

byte nitrogen() {
  digitalWrite(DE, HIGH);
  digitalWrite(RE, HIGH);
  delay(10);
  if (mod.write(nitro, sizeof(nitro)) == 8) {
    digitalWrite(DE, LOW);
    digitalWrite(RE, LOW);
    for (byte i = 0; i < 7; i++) {
      values[i] = mod.read();
      Serial.print(values[i], HEX);
    }
    Serial.println();
  }
  return values[4];
}

byte phosphorous() {
  digitalWrite(DE, HIGH);
  digitalWrite(RE, HIGH);
  delay(10);
  if (mod.write(phos, sizeof(phos)) == 8) {
    digitalWrite(DE, LOW);
    digitalWrite(RE, LOW);
    for (byte i = 0; i < 7; i++) {
      values[i] = mod.read();
      Serial.print(values[i], HEX);
    }
    Serial.println();
  }
  return values[4];
}

byte potassium() {
  digitalWrite(DE, HIGH);
  digitalWrite(RE, HIGH);
  delay(10);
  if (mod.write(pota, sizeof(pota)) == 8) {
    digitalWrite(DE, LOW);
    digitalWrite(RE, LOW);
    for (byte i = 0; i < 7; i++) {
      values[i] = mod.read();
      Serial.print(values[i], HEX);
    }
    Serial.println();
  }
  return values[4];
}

This code initializes the Arduino UNO to read values from the NPK Soil Sensor and the Capacitive Soil Moisture Sensor. The values are then printed to the Serial Monitor. The RS485 module is used for communication with the NPK Soil Sensor, and the Capacitive Soil Moisture Sensor is read using an analog pin.