Update from Farm-Team: Prototyping Update #1: sensor with nanoESP

Prototyping Update #1

Added visualisation on iobroker with values supplied over MQTT

Summary

• I had a NanoESP (aka. Pretzel-) board, which is basically a Arduino Nano board with integrated ESP8266 chip sold in Conrad Electronics (German retailer)
• Built a prototype of the sensor node using the NanoESP basically to prove our concept at an early stage
• The board would be reading Analog input of a connected hygrometer
• We powered the setup with a 5V 5 Ah portable usb powerbank (pink device on the left)



The (pink) powerbank powers the board via usb

• The board connects to an AP and the data is published over UDP
• Afterwards we started sending the data over MQTT whicht is supported by the nanoESP board. 

Shopping

• Hygrometers 3.3 - 5 V operartional current

Already available: NanoESP board, powerbank, breadboard, etc.

Testing

• Measuring  analog (moisture) value every 30 seconds
• Sending data over udp to connected devices
• Sending data over MQTT
• Battery lasts about 16 hours

Sensor testing and calibration

Used free Android UDP Receiver App to get values while connected to the device 

Code with data transmission over UDP

/*
UDP transmission
*/

#define DEBUG true

#include <SoftwareSerial.h>
#include <NanoESP.h>
SoftwareSerial esp8266(11, 12); // RX, TX

void setup() {
  Serial.begin(19200);
  esp8266.begin(19200);

  //Long Timeout needed for RST and settings of WLAN-Data
  esp8266.setTimeout(5000);
  if (sendCom("AT+RST", "ready")) {
    debug("RESET OK");
  }

  if (configAP()) {
    debug("AP ready");
  }
  if (configUDP()) {
    debug("UDP ready");
  }
  //shorter Timeout for faster wrong UPD-Comands handling
  esp8266.setTimeout(1000);

}

void loop() {
  if (esp8266.available())
  {
    int sensorValue = analogRead(A0); 
    Serial.println(sensorValue);
    delay(100);

     /* constraint function will limit the values we get so we can work better with map
     * since I only need values in the bottom limit of 300, will make it the outer limit and 1023 the other limit
     */
     sensorValue = constrain (sensorValue, 300,1023);
     // print the values returned by the sensor
     //Serial.println(sensorValue);
     // create a map with the values
     // You can think we have the 100% to 300 and 0 % to 1023 wrong, but no !
     // 300 - or 100 % - is the target value for moisture value in the soil
     // 0% of humidity - or moisture - is when the soil is dry
    int moisture = map (sensorValue, 300, 1023, 100, 0);
    String output = String(moisture) + "%";
    Serial.println(output);
    sendUDP(output);
  }

}
//-----------------------------------------Config ESP8266------------------------------------

boolean configAP()
{
  boolean succes = true;

  succes &= (sendCom("AT+CWMODE=2", "OK"));
  succes &= (sendCom("AT+CWSAP=\"NanoESP\",\"\",5,0", "OK"));

  return succes;
}

boolean configUDP()
{
  boolean succes = true;

  succes &= (sendCom("AT+CIPMODE=0", "OK"));
  succes &= (sendCom("AT+CIPMUX=0", "OK"));
  succes &= sendCom("AT+CIPSTART=\"UDP\",\"192.168.4.255\",55005,55006", "OK"); //UDP Bidirectional and Broadcast
  return succes;
}

//-----------------------------------------------Controll ESP-----------------------------------------------------

boolean sendUDP(String Msg)
{
  boolean succes = true;

  succes &= sendCom("AT+CIPSEND=" + String(Msg.length() + 2), ">");    //+",\"192.168.4.2\",90", ">");
  if (succes)
  {
    succes &= sendCom(Msg, "OK");
  }
  return succes;
}

boolean sendCom(String command, char respond[])
{
  esp8266.println(command);
  if (esp8266.findUntil(respond, "ERROR"))
  {
    return true;
  }
  else
  {
    debug("ESP SEND ERROR: " + command);
    return false;
  }
}

String sendCom(String command)
{
  esp8266.println(command);
  return esp8266.readString();
}

//-------------------------------------------------Debug Functions------------------------------------------------------
void serialDebug() {
  while (true)
  {
    if (esp8266.available())
      Serial.write(esp8266.read());
    if (Serial.available())
      esp8266.write(Serial.read());
  }
}

void debug(String Msg)
{
  if (DEBUG)
  {
    Serial.println(Msg);
  }

}

Code #2 with MQTT instead of UDP

#include <NanoESP.h>

#include <NanoESP_MQTT.h>
#include <SoftwareSerial.h>

#define SSID "XXXX"
#define PASSWORD "xxxxxxxxxxxx"
#define LED_WLAN 13
#define DEBUG true
#define mqttBroker "iot.eclipse.org"
#define mqttClientId "NanoESP"
#define mqttPort 1183

NanoESP nanoesp = NanoESP();
NanoESP_MQTT mqtt = NanoESP_MQTT(nanoesp);

void setup() {
  Serial.begin(19200);

  nanoesp.init();
  nanoesp.configWifi(STATION, SSID, PASSWORD);

  if (nanoesp.wifiConnected()) {
    Serial.println ("Wifi connected");
    digitalWrite(LED_WLAN, HIGH);
  }
  else {
    Serial.println ("Wifi not Connected");
  }
  //Print IP in Terminal
  Serial.println (nanoesp.getIp());
  if (mqtt.connect(0, mqttBroker, 1883, "NanoESP")) {
  Serial.println ("MQTT connected");
  if (mqtt.publish(0, "test", "Sensor node initial connection", 1, false)) Serial.println ("Published to test");
  if (mqtt.subscribe(0, "test", 1)) Serial.println ("Subscribed to test"); 

  if (mqtt.subscribe(0, "moisture", 1)) Serial.println ("Subscribed to moisture");
  }
}

void loop() {
  delay(random(10000));
  int id, len;
  int sensorValue = analogRead(A0); 
  sensorValue = constrain (sensorValue, 300,1023);
  int moisture = map (sensorValue, 300, 1023, 100, 0);

  if (mqtt.ping(0)) {
    Serial.println("MQTT ok comencing...");
    } else {
      //connect
      Serial.println("Setting up MQTT connection");
      mqttConnect();
    }
        
  if (nanoesp.recvData(id, len)) {
    String topic, value;
    if (mqtt.recvMQTT(id, len, topic, value)) {
      Serial.println ("New Message:\nTopic=" + topic + " Value=" + value);
    }
  } 
  mqtt.publish(0, "moisture", String(moisture));
  Serial.println(moisture);
  //if (mqtt.disconnect(0)) Serial.println("MQTT disconnected");
}

//-----------------------------------mqtt connection

void mqttConnect() {
  
  if (mqtt.connect(0, mqttBroker, 1883, "NanoESP")) {
    Serial.println ("MQTT connected");
    if (mqtt.publish(0, "test", "Sensor node reconnected", 1, false)) Serial.println ("Published to test");
    if (mqtt.subscribe(0, "test", 1)) Serial.println ("Subscribed to test");
    if (mqtt.subscribe(0, "moisture", 1)) Serial.println ("Subscribed to moisture");

    //if (MQTT_Unsubscribe(0, "test")) debug("Unsubscribed from test");
    //if (MQTT_Ping(0)) debug("Ping send ");
    //if (MQTT_Disconnect(0)) debug("Disconnect");
  }
}