This page logs my setup and ongoing experimentation for development of 'Internet of Things'.
The information is frequently 'borrowed' from other web sources (hopefully with proper acknowledgement) and may change as my experience advances.
It does not claim to be up to my normal Professional Engineering standards, but is just for experimentation in what is a 'very exciting field'.

Creating an ESP8266 MQTT SENDER:

This section will explain how to wire up and program an "ESP8266" module with an "DHT11 Sensor".

• Wire up the ESP8266 module with DHT11 Sensor as per the following drawing....
• Be very careful about the power supply to ensure the ESP-12 does not exceed 3.3Volt....
• But remember, if using a modular Power Supply module that these need 8-12 Volt input...

• Run the Arduino IDE and open a new 'Sketch' which contains some suggested code.
• Select and Copy the all text from the following window.
• Paste all the text (overwriting the new 'Sketch' suggestions).
• Update the 'WIFINAME', 'PASSWORD' and 'mqtt_server' with your values.
• If you Network uses an Address other the 192.168.1.xxx enter IPADDRESS and ROUTER_ADDRESS.
• 'File => Save As' the Sketch 'ESP8266_DHT_lounge_192' .
• (The naming convention includes the location 'lounge' and the IP address '192'.)
• Ensure that the Tools => Board: is set to 'Generic ESP8266 Module'
• 'Verify / Compile' the Sketch.
• Place a jumper between GPIO0 and GROUND.
• Press the Reset button and 'Upload' the Sketch.
• Remove the programming jumper and press the Reset button again.
• Create the other ESP8266 boards and load 'ESP8266_DHT_kitchen_193' etc.

//===================================================================================== // ESP8266 Digital Humidity Sensor Client. [Title is ESP8266_DHT_lounge_192] // [Last Updated: 12-AUG-2016 at 11:55PM] // Currently setup at a fixed IP Address and 10 second delay between messages. //===================================================================================== #include <ESP8266WiFi.h> #include <PubSubClient.h> #include <DHT.h> #define DHTTYPE DHT11 #define DHTPIN 12 //===================================================================================== // Update these for Each ESP8266 device based on where it will be located. //===================================================================================== // CHANGE THESE VALUES FOR EACH ESP-12 MODUULE ///////////////////////////////////// const char* client_name = "ESP8266_DHT_lounge"; // unique client name const char* Topic_Name1 = "lounge/temperature"; // unique publish stream (temperature) const char* Topic_Name2 = "lounge/humidity"; // unique publish stream (humidity) #define IPADDRESS IPAddress(192, 168, 1, 192) // unique fixed IP address // Last number of IP address is included in the 'sketch' title //===================================================================================== // Update these with values suitable for your actual network. (Same for all ESP devices) //===================================================================================== const char* mqtt_server = "192.168.1.20"; // The address of your Raspberry Pi const char* ssid = "WIFINAME"; // The 'id' of your wifi network const char* password = "PASSWORD"; // The password for wifi network #define ROUTER_ADDRESS IPAddress(192, 168, 1, 1) // Actual IP address of the Wireless Router //===================================================================================== // Initialize DHT sensor DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266 float humidity, temp_c; // Values read from sensor unsigned long previousMillis = 0; // will store last temp was read const long interval = 2000; // interval at which to read sensor WiFiClient espClient; PubSubClient client(espClient); long lastMsg = 0; int value = 0; char msg[50]; char msg1[20]; char msg2[50]; //========================================================================== // MAIN SETUP //========================================================================== void setup() { //pinMode(BUILTIN_LED, OUTPUT); // Initialize the BUILTIN_LED pin as an output Serial.begin(9600); setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); } //========================================================================== // SETUP WIFI //========================================================================== void setup_wifi() { delay(10); // We start by connecting to a WiFi network sprintf(msg, "Program is: %s_LAST_IP_NUMBER" , client_name ); Serial.println(msg); Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); WiFi.config( IPADDRESS, ROUTER_ADDRESS, IPAddress(255, 255, 255, 0)); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP()); } //========================================================================== // CALLBACK //========================================================================== void callback(char* topic, byte* payload, unsigned int length) { Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); } Serial.println(); } //========================================================================== // RECONNECT // It connects to an MQTT server then: // - subscribes to the topic "inTopic", printing out any messages // it receives. NB - it assumes the received payloads are strings not binary // It will reconnect to the server if the connection is lost using a blocking // reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to // achieve the same result without blocking the main loop. //========================================================================== void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect if (client.connect(client_name)) { Serial.println("connected"); // Once connected, publish an announcement... client.publish("outTopic", "hello world"); // ... and resubscribe client.subscribe("inTopic"); } else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); } } } //========================================================================== // MAIN LOOP //========================================================================== void loop() { if (!client.connected()) { reconnect(); } client.loop(); long now = millis(); if (now - lastMsg > 5000) { lastMsg = now; ++value; gettemperature(); Serial.print("Sending temperature and humidity: "); Serial.print(temp_c); Serial.print(" : "); Serial.println(humidity); dtostrf(temp_c , 2, 1, msg); dtostrf(humidity , 2, 1, msg1); sprintf( msg2, "%s", msg ) ; client.publish(Topic_Name1, msg2); client.publish(Topic_Name2, msg1); } } //========================================================================== // GET TEMPERATURE // Wait at least 2 seconds seconds between measurements. // if the difference between the current time and last time you read // the sensor is bigger than the interval you set, read the sensor // Works better than delay for things happening elsewhere also //========================================================================== void gettemperature() { unsigned long currentMillis = millis(); if(currentMillis - previousMillis >= interval) { // save the last time you read the sensor previousMillis = currentMillis; // Reading temperature for humidity takes about 250 milliseconds! // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor) humidity = dht.readHumidity(); // Read humidity (percent) temp_c = dht.readTemperature(); // Read temperature as Celcius // Check if any reads failed and exit early (to try again). if (isnan(humidity) || isnan(temp_c)) { Serial.println("Failed to read from DHT sensor!"); return; } } }

• This is the Scematic for the above ESP8266 wiring...

Creating an ESP01 PCB Version of the MQTT SENDER:

This section will explain how to create and program an "ESP01" module with a "DHT11 Sensor", and an external sensor input - that can be connected to a PIR Motion Detector.

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• Note - This module is designed run from a 5volt plugpack....
• It can also be powered from batteries (4 x AA cells) using a three pin connector....
• The three pin connector is wired with +6v on the Middle pin and GROUND on both outside pins...
• This ensures that it cannot be plugged in the wrong way.

Connections for new ESP01 PCB . To program the PCB; a jumper must be placed across the 'Flash' connector and the RESET button (just beside the jumper) must be pressed. . The USB FTTDI Adapter provides the connection to the programming computer. . The three wires plugged into the board (just behind the Regulator IC), are for the connection to the HC-SR501 PIR detector. They are: RED (Plus 5volt) BROWN (PIR output) BLACK (Ground) .

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This is the new PCB for the above ESP01 wiring...

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• The 'Sketch' software for this module has several features to support the HC-SR501 sensor....
• The ESP01 Arduino IDE 'Sketch' software for this module has been named "ESP01_DHT_Outdoor_PIR_195" ..
• All messages are returned under the 'outdoor/pir' topic as a decimal number eg: '50.1', '00.9', or '99.9'....
• Initialization can take up to 60 seconds, before readings can be trusted...
• ...During this time it will send '50.1', '50.2' etc and will ignore any status until after '50.6'....
• A High state will be returned as numbers starting with '99.1', '99.2'... increasing every 10 seconds up to '99.9' ...
• A Low state will be returned as numbers starting with '00.1', '00.2'... increasing every 10 seconds up to '00.9' ...
• This allows the OpenHAB application to work out how long it should wait for each transition ...

Software for "ESP01_DHT_outdoor_PIR_195"

Follow the instructions earlier on this page to load this Arduino 'Sketch'.

//===================================================================================== // ESP01 Digital Humidity Sensor Client. [ EARLY DRAFT: NEEDS A CLEAN UP! ] // [Last Updated: 19-AUG-2016 at 11:50PM] // Currently setup at a fixed IP Address and 10 second delay between messages. //===================================================================================== // It connects to an MQTT server then: // - subscribes to the topic "inTopic", printing out any messages // it receives. NB - it assumes the received payloads are strings not binary // ///It will reconnect to the server if the connection is lost using a blocking ///reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to ///achieve the same result without blocking the main loop. // The 'Sketch' software for this module has several features to support the HC-SR501 sensor. // The ESP01 Arduino IDE 'Sketch' software for this module has been named "ESP01_DHT_outdoor_PIR_195" // All messages are returned under the 'outdoor/pir' topic as a decimal number eg: '50.1', '00.9', or '99.9'. // Initialization can take up to 60 seconds, before readings can be trusted. // ..... During this time it will send '50.1', '50.2' etc and will ignore any status until after '50.6'. // A High state will be returned as numbers starting with '99.1', '99.2'... increasing every 10 seconds up to '99.9'. // A Low state will be returned as numbers starting with '00.1', '00.2'... increasing every 10 seconds up to '00.9'. // This allows the OpenHAB application to work out how long it should wait for each transition ... </li> #include <ESP8266WiFi.h> #include <PubSubClient.h> #include <DHT.h> #define DHTTYPE DHT11 #define DHTPIN 2 #define PIRPIN 0 //===================================================================================== // Update these for Each ESP01 device based on where it will be located. //===================================================================================== // CHANGE THESE VALUES FOR EACH ESP01 MODUULE /////////////////////////////////////// const char* client_name = "ESP01_DHT_outdoor"; // unique client name const char* Topic_Name1 = "outdoor/temperature"; // unique publish stream (temperature) const char* Topic_Name2 = "outdoor/humidity"; // unique publish stream (humidity) const char* Topic_Name3 = "outdoor/pir"; // unique publish stream (pir) #define IPADDRESS IPAddress(192, 168, 1, 195) // unique fixed IP address included in the 'sketch' name //===================================================================================== // Update these with values suitable for your network. //===================================================================================== const char* mqtt_server = "192.168.1.20"; const char* ssid = "NETGEAR"; const char* password = "1234509876"; #define ROUTER_ADDRESS IPAddress(192, 168, 1, 1) // Actual IP address of the Wireless Router //===================================================================================== // Initialize DHT sensor // NOTE: For working with a faster than ATmega328p 16 MHz Arduino chip, like an ESP8266, // you need to increase the threshold for cycle counts considered a 1 or 0. // You can do this by passing a 3rd parameter for this threshold. It's a bit // of fiddling to find the right value, but in general the faster the CPU the // higher the value. The default for a 16mhz AVR is a value of 6. For an // Arduino Due that runs at 84mhz a value of 30 works. // This is for the ESP8266 processor on ESP-01 DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266 float humidity, temp_c; // Values read from sensor // (Generally, you should use "unsigned long" for variables that hold time) unsigned long previousMillis = 0; // will store last temp was read const long interval = 2000; // interval at which to read sensor WiFiClient espClient; PubSubClient client(espClient); long lastMsg = 0; int value = 0; char msg[50]; char msg1[20]; char msg2[50]; char *msg_init = "50.0"; // default message during 'init' phase char *msg_low = "00.0"; // default message during 'low' state char *msg_high = "99.0"; // default message during 'high' state int count_init = 0; // count of 10 second scans in init state int count_high = 0; // count of 10 second scans in init state int count_low = 0; // count of 10 second scans in init state int last_state = 5; // Last state (5=init, 0=low, 9=high) //========================================================================== // MAIN SETUP //========================================================================== void setup() { last_state = 5; Serial.begin(9600); pinMode(PIRPIN, INPUT); digitalWrite(PIRPIN, HIGH); // Not sure what this could do on an 'INPUT' setup_wifi(); client.setServer(mqtt_server, 1883); client.setCallback(callback); } //========================================================================== // SETUP WIFI //========================================================================== void setup_wifi() { delay(10); // We start by connecting to a WiFi network sprintf(msg, "Program is: %s_LAST_IP_NUMBER" , client_name ); Serial.println(msg); // Serial.println("ESP8266_DHT_outdoor_192"); Serial.print("Connecting to "); Serial.println(ssid); WiFi.begin(ssid, password); // WiFi.config( IPADDRESS, IPAddress(192, 168, 1, 1), IPAddress(255, 255, 255, 0)); WiFi.config( IPADDRESS, ROUTER_ADDRESS, IPAddress(255, 255, 255, 0)); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.println("IP address: "); Serial.println(WiFi.localIP()); } //========================================================================== // CALLBACK //========================================================================== void callback(char* topic, byte* payload, unsigned int length) { Serial.print("Message arrived ["); Serial.print(topic); Serial.print("] "); for (int i = 0; i < length; i++) { Serial.print((char)payload[i]); } Serial.println(); } //========================================================================== // RECONNECT //========================================================================== void reconnect() { // Loop until we're reconnected while (!client.connected()) { Serial.print("Attempting MQTT connection..."); // Attempt to connect if (client.connect(client_name)) { Serial.println("connected"); // Once connected, publish an announcement... client.publish("outTopic", "hello world"); // ... and resubscribe client.subscribe("inTopic"); } else { Serial.print("failed, rc="); Serial.print(client.state()); Serial.println(" try again in 5 seconds"); // Wait 5 seconds before retrying delay(5000); } } } //========================================================================== // MAIN LOOP //========================================================================== void loop() { if (!client.connected()) { reconnect(); } client.loop(); char msg9[40]; long now = millis(); if (now - lastMsg > 5000) { lastMsg = now; ++value; // Check the state of the PIR Sensor.. if ( last_state == 5 ) { // state = Initializing -- must loop past here 6 times.. count_init++; msg_init[3] = '0' + count_init; // convert number 1..6 to ASCII '0'..'6' sprintf(msg9, "PIR Initialization %s", msg_init); Serial.println(msg9); client.publish(Topic_Name3, msg_init); if (count_init > 6 ) { last_state = 0; // set 'state' to presume no movement count_init = 0; // count of 10 second scans in init state count_high = 0; // count of 10 second scans in init state count_low = 0; // count of 10 second scans in init state } } else { if (digitalRead(PIRPIN) == LOW) { // THIS ACTUALLY HIGH STATE 99.9 if( last_state == 0 ) { // Do this only on the Low->High Transition time last_state = 9; // set 'state' count_high = 0; // reset count for 10 second scans in 'high' state count_low = 0; // reset count for 10 second scans in 'low' state } if (count_high < 9 ) { // only increment count up to 9. count_high++; } msg_high[3] = '0' + count_high; // convert number 1..9 to ASCII '0'..'9' sprintf(msg9, "PIR motion detected: %s", msg_high); Serial.println(msg9); client.publish(Topic_Name3, msg_high); } else { // THIS ACTUALLY LOW STATE 00.0 if( last_state == 9 ) { // Do this only on the High->Low Transition time last_state = 0; // set 'state' count_high = 0; // reset count for 10 second scans in 'high' state count_low = 0; // reset count for 10 second scans in 'low' state } if (count_low < 9 ) { // only increment count up to 9. count_low++; } msg_low[3] = '0' + count_low; // convert number 1..9 to ASCII '0'..'9' sprintf(msg9, "NO PIR motion detected: %s", msg_low); Serial.println(msg9); client.publish(Topic_Name3, msg_low); } } delay(5); gettemperature(); Serial.print("Sending temperature and humidity: "); Serial.print(temp_c); Serial.print(" : "); Serial.println(humidity); dtostrf(temp_c , 2, 1, msg); dtostrf(humidity , 2, 1, msg1); sprintf( msg2, "%s", msg ) ; client.publish(Topic_Name1, msg2); client.publish(Topic_Name2, msg1); } } //========================================================================== // GET TEMPERATURE // Wait at least 2 seconds seconds between measurements. // if the difference between the current time and last time you read // the sensor is bigger than the interval you set, read the sensor // Works better than delay for things happening elsewhere also //========================================================================== void gettemperature() { unsigned long currentMillis = millis(); if(currentMillis - previousMillis >= interval) { // save the last time you read the sensor previousMillis = currentMillis; // Reading temperature for humidity takes about 250 milliseconds! // Sensor readings may also be up to 2 seconds 'old' (it's a very slow sensor) humidity = dht.readHumidity(); // Read humidity (percent) temp_c = dht.readTemperature(); // Read temperature as Celcius // Check if any reads failed and exit early (to try again). if (isnan(humidity) || isnan(temp_c)) { Serial.println("Failed to read from DHT sensor!"); return; } } }

Last updated: 20-AUG-2016 at 03:05PM.