Networking & Communications

For the week, Ruben and I teamed up to extend the research on Duckweed from Term 1 to design a Distributed and Independent Monitoring System. The core aim was to monitor the health for the Duckweed plants so as that to grow them in a healthy and efficient way. This could be achieved by controlling the nutrition and strains of proteins grown, for consumption in the later stage. The same system could be used my multiple individuals and multiple locations for any plants in any mediums be it aquatic plants, terrestrial plants or even aerial plants.

The first approach involved running Musquitto on a Raspberry Pi to serve as broker for the MQTT protocol, between the DigitalOcean server programmed on a ESP8266 micro-controller. Since ESP8266 has only one Analog pin, we would not read the phototransistor and temperature sensor at the same time. Therefore the decision to replace ESP8266 with an ESP32 was made. Certain pins were revised with the Wifi setup and MQTT communications. The code was re-run the with both sensor inputs at the same time.

The assembled code for the Arduino IDE sketch, consisting the Wifi, MQTT setup and commands for gathering data from various sensors, can be found below:

#include
#include "DHT.h"
#define DHTPIN 21
#define DHTTYPE DHT11 //Wifi setup
const char* ssid = "Iaac-Wifi";
const char* password = "EnterIaac22@";
const char* mqtt_server = "167.99.44.189";
WiFiClient espClient;
PubSubClient client(espClient);
//Temperature probe setup
OneWire oneWire(14);
DallasTemperature tempSensor(&oneWire);
float MT;
float MM;
const int DHTPin = 21;
const int lamp = 23;
// Initialize DHT sensor.
DHT dht(DHTPin, DHTTYPE);
// Timers auxiliar variables
long now = millis();
long lastMeasure = 0;
void setup_wifi() {
delay(10);
// We start by connecting to a WiFi network
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.print("WiFi connected - ESP IP address: ");
Serial.println(WiFi.localIP());
}
void callback(String topic, byte* message, unsigned int length) {
Serial.print("Message arrived on topic: ");
Serial.print(topic);
Serial.print(". Message: ");
String messageTemp;
for (int i = 0; i < length; i++) {
Serial.print((char)message[i]);
messageTemp += (char)message[i];
}
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Serial.println();
if(topic=="air/lamp"){
Serial.print("Changing Room lamp to ");
if(messageTemp == "on"){
digitalWrite(lamp, HIGH);
Serial.print("On");
}
else if(messageTemp == "off"){
digitalWrite(lamp, LOW);
Serial.print("Off");
}
}
Serial.println();
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect if (client.connect("ESP8266Client")) {
Serial.println("connected");
// Subscribe or resubscribe to a topic
// You can subscribe to more topics (to control more LEDs in this example)
client.subscribe("air/lamp");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
void setup() {
// LED output?
pinMode(lamp, OUTPUT);
dht.begin();
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
Serial.println("Dallas Temperature IC Control Library Demo");
//sensors.begin();
}
void loop() {
// Moisture Media Sensor
Serial.print("Moisture Sensor Value:");
Serial.println(analogRead(A3));
delay(100);
MM = analogRead(A3); // Phototransistor
int value = analogRead(33);
int perValue = map(value,0,1024,0,100);
Serial.println("Phototransistor: ");
Serial.println(value);
delay(50); // Temperature Media probe
MT = tempSensor.getTempCByIndex(0);
tempSensor.requestTemperaturesByIndex(0);
Serial.print("Media Temperature: ");
Serial.print(tempSensor.getTempCByIndex(0));
Serial.println(" C");
delay(50);
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if (!client.connected())
reconnect();
client.loop();
long now = millis();
if (now - lastMeasure > 50) {
lastMeasure = now;
float h = dht.readHumidity();
float t = dht.readTemperature();
float f = dht.readTemperature(true); // Check if any reads failed and exit early (to try again).
if (isnan(h) || isnan(t) || isnan(f)) {
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Serial.println("Failed to read from DHT sensor!");
return;
}

float hic = dht.computeHeatIndex(t, h, false);
static char temperatureTemp[7];
dtostrf(hic, 6, 2, temperatureTemp);
static char humidityTemp[7];
dtostrf(h, 6, 2, humidityTemp);
static char mediatemperatureTemp[7];
dtostrf(MT, 6, 2, mediatemperatureTemp);
static char mediamoistureMois[7];
dtostrf(MM, 6, 2, mediamoistureMois);
static char lightLight[7];
dtostrf(perValue, 6, 2, lightLight); // Publishes Temperature and Humidity values

client.publish("air/temperature", temperatureTemp);
client.publish("air/humidity", humidityTemp);
client.publish("media/temperature", mediatemperatureTemp);
client.publish("air/light", lightLight);
client.publish("media/moisture", mediamoistureMois);

Serial.print("Aerial Humidity: ");
Serial.print(h);
Serial.print(" %\t Aerial Temperature: ");
Serial.print(t);
Serial.print(" *C ");
Serial.print(f);
Serial.print(" *F\t Heat index: ");
Serial.print(hic);
Serial.println(" *C ");
}
}

Fig. 10.1 The communications across servers and devices involved in the project.