M5 Stack Earth Moisture Unit

M5 Stack Earth Moisture Unit Documentation

Overview

The M5 Stack Earth Moisture Unit is a sensor module designed to measure the moisture level in soil. It is a popular IoT component used in agriculture, gardening, and environmental monitoring projects. This unit is compatible with the M5 Stack development board and provides an easy-to-use interface for measuring soil moisture levels.

Technical Specifications

Operating Voltage: 3.3V to 5.5V
 Communication Protocol: I2C
 Measurement Range: 0-100% soil moisture
 Accuracy: 5%
 Response Time: 10ms

Pinout

The M5 Stack Earth Moisture Unit has a 4-pin interface:

VCC (Red wire): Connect to the power supply (3.3V to 5.5V)
 GND (Black wire): Connect to the ground
 SCL (Yellow wire): Connect to the I2C clock pin (SCL)
 SDA (White wire): Connect to the I2C data pin (SDA)

Example Code 1: Basic Soil Moisture Measurement

This example demonstrates how to use the M5 Stack Earth Moisture Unit to measure the soil moisture level and display it on the M5 Stack's built-in LCD screen.
```c
#include <M5Stack.h>
#include <Wire.h>

#define MOISTURE_UNIT_ADDRESS 0x36 // I2C address of the M5 Stack Earth Moisture Unit

M5Stack m5;

void setup() {
  m5.begin();
  Wire.begin();
}

void loop() {
  int moistureLevel = 0;
  Wire.beginTransmission(MOISTURE_UNIT_ADDRESS);
  Wire.write(0x00); // Register address for moisture measurement
  Wire.endTransmission();
  Wire.requestFrom(MOISTURE_UNIT_ADDRESS, 1);
  moistureLevel = Wire.read();

m5.Lcd.setCursor(0, 0);
  m5.Lcd.print("Soil Moisture: ");
  m5.Lcd.print(moistureLevel);
  m5.Lcd.print("%");

delay(1000);
}
```
Example Code 2: Automating Watering System

This example demonstrates how to use the M5 Stack Earth Moisture Unit to automate a watering system. When the soil moisture level falls below a certain threshold, the system triggers a relay module to turn on a water pump.
```c
#include <M5Stack.h>
#include <Wire.h>

#define MOISTURE_UNIT_ADDRESS 0x36 // I2C address of the M5 Stack Earth Moisture Unit
#define RELAY_PIN 22 // Pin connected to the relay module

M5Stack m5;

void setup() {
  m5.begin();
  Wire.begin();
  pinMode(RELAY_PIN, OUTPUT);
}

void loop() {
  int moistureLevel = 0;
  Wire.beginTransmission(MOISTURE_UNIT_ADDRESS);
  Wire.write(0x00); // Register address for moisture measurement
  Wire.endTransmission();
  Wire.requestFrom(MOISTURE_UNIT_ADDRESS, 1);
  moistureLevel = Wire.read();

if (moistureLevel < 30) { // Soil moisture level threshold
    digitalWrite(RELAY_PIN, HIGH); // Turn on the water pump
  } else {
    digitalWrite(RELAY_PIN, LOW); // Turn off the water pump
  }

delay(1000);
}
```
Example Code 3: IoT-Based Soil Moisture Monitoring

This example demonstrates how to use the M5 Stack Earth Moisture Unit to send soil moisture data to a cloud-based IoT platform (e.g., MQTT) using a Wi-Fi module.
```c
#include <M5Stack.h>
#include <Wire.h>
#include <WiFi.h>
#include <PubSubClient.h>

#define MOISTURE_UNIT_ADDRESS 0x36 // I2C address of the M5 Stack Earth Moisture Unit
#define WIFI_SSID "your_wifi_ssid"
#define WIFI_PASSWORD "your_wifi_password"
#define MQTT_SERVER "your_mqtt_server"
#define MQTT_PORT 1883
#define MQTT_TOPIC "soil_moisture"

M5Stack m5;
WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
  m5.begin();
  Wire.begin();
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");
  client.setServer(MQTT_SERVER, MQTT_PORT);
}

void loop() {
  int moistureLevel = 0;
  Wire.beginTransmission(MOISTURE_UNIT_ADDRESS);
  Wire.write(0x00); // Register address for moisture measurement
  Wire.endTransmission();
  Wire.requestFrom(MOISTURE_UNIT_ADDRESS, 1);
  moistureLevel = Wire.read();

if (!client.connected()) {
    reconnect();
  }
  client.loop();

char soilMoistureString[10];
  sprintf(soilMoistureString, "%d", moistureLevel);
  client.publish(MQTT_TOPIC, soilMoistureString);

delay(1000);
}

void reconnect() {
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    if (client.connect("M5StackClient")) {
      Serial.println("connected");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      delay(5000);
    }
  }
}
```
These examples demonstrate the basic usage of the M5 Stack Earth Moisture Unit in various IoT applications. You can modify and extend these examples to fit your specific project requirements.