Precision Soil NPK & pH Sensor with RS485 Modbus Telemetry

Educational Notes

This project is designed to be accessible to students from Class 4 to Masters level, with complexity scalable to match different age groups and skill levels.

Learning Objectives:

• Understand basic electronics and circuitry principles
• Learn sensor applications and data collection techniques
• Develop problem-solving skills through hands-on building and troubleshooting
• Apply programming concepts to control hardware and process data
• Connect projects to real-world Nepalese contexts and challenges

Adaptability:

• For younger students (Class 4-8): Focus on assembling pre-built circuits, observing results, and understanding basic concepts
• For intermediate students (Class 9-12): Modify code, experiment with parameters, and explore underlying principles
• For advanced students (Undergraduate/Masters): Optimize designs, add features, conduct research extensions, and analyze performance

Safety Note: Always supervise younger students when working with electricity, heat, or moving parts.

Industrial agriculture sensors communicate using RS485 Modbus RTU protocol to ensure noise-immune readings over long field wire lengths.

Hardware Bill of Materials:

• Microcontroller: Arduino Nano V3.0 Solderless
• RS485 Transceiver: MAX485 TTL To RS485 Module
• Soil Probe: Soil Sensor JXBS-3001 NPK RS
• Display: 1602 (16x2) LCD Display with I2C/IIC interface - Blue Backlight
• Power: 9V Battery with 10CM DC 9V 5.5*2.1mm Battery Button Power Plug

Circuit Pinout & Wiring Connections:

Firmware Source Code (Arduino Uno C++)

#include <Wire.h>
#include <EEPROM.h>

// L298N Motor Driver Pin Connections
const int ENA = 5;
const int IN1 = 18;
const int IN2 = 19;
const int IN3 = 21;
const int IN4 = 22;
const int ENB = 23;

void setup() {
  Serial.begin(9600);
  pinMode(ENA, OUTPUT);
  pinMode(ENB, OUTPUT);
  pinMode(IN1, OUTPUT);
  pinMode(IN2, OUTPUT);
  pinMode(IN3, OUTPUT);
  pinMode(IN4, OUTPUT);
  Serial.println("Robotic Chassis & Motor Driver Controller Active.");
}

void moveForward(int speedVal) {
  analogWrite(ENA, speedVal);
  analogWrite(ENB, speedVal);
  digitalWrite(IN1, HIGH);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, HIGH);
  digitalWrite(IN4, LOW);
}

void stopMotors() {
  digitalWrite(IN1, LOW);
  digitalWrite(IN2, LOW);
  digitalWrite(IN3, LOW);
  digitalWrite(IN4, LOW);
}

void loop() {
  Serial.println("Executing Autonomous Drive Routine Forward...");
  moveForward(200);
  delay(3000);
  Serial.println("Stopping Motors...");
  stopMotors();
  delay(2000);
}