Smart fertilizer and crop recommendation system using Arduino an NPK sensor

[yelbe]

Hello everyone,

I am currently developing a smart fertilizer and crop recommendation system using Arduino (NodeMCU) along with an NPK sensor to measure soil nutrients. However, I am encountering an issue with the data readings. When I receive data from the sensor to the Arduino, it consistently displays a value of 255 for each parameter (Nitrogen, Phosphorus, and Potassium) regardless of the actual soil condition. This same value is also displayed even when the sensor is not inserted in the soil.

Has anyone experienced a similar issue or can provide insights on why this might be happening? Any suggestions on troubleshooting steps or potential fixes would be greatly appreciated.

Thank you!

this is the code

#include <SoftwareSerial.h>
#include <Wire.h>
#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

// #include <Adafruit_GFX.h>
// #include <Adafruit_SSD1306.h>

#define RE 4
#define DE 5
#define DI 14
#define RO 2

// const byte phv[] = {0x01, 0x03, 0x00, 0x06, 0x00, 0x01, 0x64, 0x0b};
// 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};




//const byte temp[] = {0x01,0x03, 0x00, 0x13, 0x00, 0x01, 0x75, 0xcf};//
const byte temp[] = {0x01,0x03, 0x01, 0x13, 0x22, 0x01, 0x75, 0xcf};

const byte mois[]  = {0x01,0x03,0x00,0x12,0x00,0x01,0x24,0x0F};

const byte econ[] = {0x01,0x03, 0x00, 0x15, 0x00, 0x01, 0x95, 0xce};

const byte phv[] = {0x01,0x03, 0x00, 0x06, 0x00, 0x01, 0x64, 0x0b};//0x0B64

//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 };



// const byte nitro[) = (0x01,0x03, 0x00, Oxle, 0x00, 0x01, Oxed, OxOc):
// const byte phos(] = (0x01,0x03, 0x00, Oxif, 0x00, 0x01, ORbS, Oxce):
// const byte pota(] = (0x01,0x03, 0x00, 0x20, 0x00, 0x0l, ORES, Oxc0);
// const byte soil ph(] = (0x01, 0x03, 0x00, 0x06, 0x00, 0x01, Oxéd, Cxib):
// const byte soil moist(] = (0X01, 0x03, 0800, 0x12, 0X00, 0X01, 0x24, OXOf):
// const bye templ] = (0x01, O03, 0x00, 0x12, 0x00, 0x02, Oxéd, Uxde):
// const byte ec] = (0301, 0x03, 0x00, OK1S, 0x00, 0x01, 0x95, Oxce):

const char* ssid = "cont";
const char* password = "098765432";

const char* serverName = "http://192.168.137.217/Gc/gc_project/display.php";

String apiKeyValue = "Y5UPLPLDCO4154WW";

byte values[11];
SoftwareSerial mod(RO, DI);

void setup() {
  Serial.begin(9600);
  mod.begin(4800);
  WiFi.begin(ssid, password);
  Serial.print("Connecting to WiFi");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  Serial.println("Connected to WiFi");
  Serial.print("IP Address: ");
  Serial.println(WiFi.localIP());
  Serial.println("i am in setup");
  pinMode(RE, OUTPUT);
  pinMode(DE, OUTPUT);
  Serial.print("Nitrogen: ");
  delay(3000);
}

void loop() {






  
  byte n, p, k, h;
  n = nitrogen();
  delay(250);
  p = phosphorous();
  delay(250);
  k = potassium();
  delay(250);
  h = ph();
  delay(250);

  Serial.print("Nitrogen: ");
  Serial.print(n);
  Serial.println(" mg/kg");
  Serial.print("Phosphorous: ");
  Serial.print(p);
  Serial.println(" mg/kg");
  Serial.print("Potassium: ");
  Serial.print(k);
  Serial.println(" mg/kg");
  Serial.print("pH: ");
  Serial.println(h);

  if (WiFi.status() == WL_CONNECTED) {
    WiFiClient client;
    HTTPClient http;
    String serverPath = String(serverName) + "?nitrogen=" + String(n) + "&phosphorus=" + String(p) + "&potassium=" + String(k) + "&ph=" + String(h);

    http.begin(client, serverPath);

    int httpResponseCode = http.GET();

    if (httpResponseCode > 0) {
      String payload = http.getString();
      Serial.print("HTTP Response code: ");
      Serial.println(httpResponseCode);
      Serial.println("Response payload: " + payload);
    } else {
      Serial.print("Error code: ");
      Serial.println(httpResponseCode);
    }
    http.end();
  } else {
    Serial.println("WiFi Disconnected");
  }
  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();
      values[i] = mod.read();
    }
  }
  return values[3];
}

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();
    }
  }
  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();
    }
  }
  return values[5];
}

byte ph() {
  digitalWrite(DE, HIGH);
  digitalWrite(RE, HIGH);
  delay(10);
  if (mod.write(phv, sizeof(phv)) == 8) {
    digitalWrite(DE, LOW);
    digitalWrite(RE, LOW);
    for (byte i = 0; i < 7; i++) {
      values[i] = mod.read();
    }
  }
  return values[6];
}

[rsmls]

NPK sensors like the one you've got are bogus. There's fundamentally no way to even remotely accurate determine N, P and K levels electrically with a simple probe. Sorry, but forget about this approach; it's not going anywhere.

[gilshultz]

Welcome! Post both your code and an annotated schematic, we cannot see what you have or how it is connected. Show all connections and any external components such as resistors, capacitors, etc. Give links to technical information on each hardware item. Doing this should get you a more accurate answer and much quicker.

[xfpd]

@yelbe

I am encountering an issue with the data readings

Show your code.

@rsmls

no way to even remotely accurate determine N, P and K levels electrically

Although the probes are made of different material (some are aluminum, some are steel) the conduction of the soil depends upon liquid, not the number of atoms per trace element. If you search on this forum, you will probably not find a definitive solution (heh) to measuring NPK with these devices.

However; the coding exercise is good. For that reason alone, you should follow this through to completing the code. Ask any question.

[rsmls]

@xfpd

However; the coding exercise is good.

There's that, yes. It should definitely be possible to get something else than all 0xFF's from the sensor. At that point, the output may still be meaningless, but it's still a neat random number generator!

[yelbe]

i just post both now. sir

[jremington]

Please edit your post to add code tags. Instructions are given in the "How to get the best out of this forum" post.

[yelbe]

sorry sir, i will.

[kmin]

It's not very clear on the photos.
Can you write where all the pins of max485 are going (arduino/sensor).