Hey all. My first project is an EC/Soil Salinity sensor using an Arduino nano, OLED display, and Modbus. I followed this tutorial: DIY Soil EC/Salinity Meter || Measure Soil Conductivity & Salinity using Arduino & Soil EC Sensor - YouTube. The EC value stays at -1 instead of changing as it should.
#include <SoftwareSerial.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#define RE 8
#define DE 7
const byte ec[] = {0x01, 0x03, 0x00, 0x15, 0x00, 0x01, 0x95, 0xCE};
const byte salinity[] = {0x01, 0x03, 0x00, 0x14, 0x00, 0x01, 0xC4, 0x0E};
byte values[8];
SoftwareSerial mod(2, 3);
#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1 // Reset pin # (or -1 if sharing reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);
void setup()
{
Serial.begin(9600);
mod.begin(9600);
pinMode(RE, OUTPUT);
pinMode(DE, OUTPUT);
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C))
{
Serial.println(F("SSD1306 allocation failed"));
for (;;); // Don't proceed, loop forever
}
display.display();
delay(100);
display.clearDisplay();
display.setTextColor(WHITE);
display.setTextSize(1);
display.setCursor(20, 30);
display.print("Soil Analysis");
display.display();
delay(2000);
}
void loop()
{
/**************Soil EC Reading*******************/
digitalWrite(DE, HIGH);
digitalWrite(RE, HIGH);
delay(10);
if (mod.write(ec, sizeof(ec)) == 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();
}
int soil_ec = int(values[3]<<8|values[4]);
delay(1000);
/**************Soil Salinity Reading*******************/
digitalWrite(DE, HIGH);
digitalWrite(RE, HIGH);
delay(10);
if (mod.write(salinity, sizeof(salinity)) == 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();
}
int soil_salinity = int(values[4]);
delay(100);
Serial.print("Soil EC: ");
Serial.println(soil_ec);
Serial.print("Soil Salinity: ");
Serial.println(soil_salinity);
display.clearDisplay();
display.setTextSize(2);
display.setCursor(0,10);
display.print("EC:");
display.print(soil_ec);
display.setTextSize(1);
display.print(" us/cm");
display.setTextSize(2);
display.setCursor(0,40);
display.print("SL:");
display.print(soil_salinity);
display.setTextSize(1);
display.print(" mg/L");
display.display();
delay(200);
}