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-====== Practical Consolidation Session ======+====== Practical Evaluation: Building an End-to-End IoT Temperature Monitoring Stack ====== 
 + 
 +===== Context ===== 
 + 
 +Over the past three days, you built a complete IoT data pipeline using an ESP32, an analog soil moisture sensor, WiFi, MQTT, Node-RED, InfluxDB, and Grafana. 
 + 
 +You practiced each layer of the IoT stack: 
 +  * Connecting a sensor to a microcontroller 
 +  * Reading sensor values in Arduino code 
 +  * Applying simple logic to sensor readings 
 +  * Controlling an LED based on a condition 
 +  * Connecting the ESP32 to WiFi 
 +  * Publishing data through MQTT using the PubSubClient library 
 +  * Receiving MQTT messages in Node-RED 
 +  * Pre-processing incoming values in Node-RED 
 +  * Writing processed values into InfluxDB 
 +  * Connecting Grafana to InfluxDB 
 +  * Creating a Grafana dashboard to visualize sensor measurements 
 + 
 +For this evaluation, you will repeat the same IoT stack, but with a different sensor: the **DS18B20 digital temperature sensor**. 
 + 
 +The goal is not to test memorization. You are allowed to use the provided schematic, diagrams, starter code, previous workshop notes, and examples. 
 + 
 +The goal is to demonstrate that you understand how the parts of the IoT stack connect and that you can adapt the workflow to a new sensor. 
 + 
 +====== Evaluation Task ====== 
 + 
 +===== Main Objective ===== 
 + 
 +Build a working IoT temperature monitoring system using the **ESP32** and **DS18B20 temperature sensor**, then send the temperature data through the full IoT stack: 
 + 
 +<code> 
 +DS18B20 → ESP32 → WiFi → MQTT → Node-RED → InfluxDB → Grafana 
 +</code> 
 + 
 +At the end of the evaluation, your system should: 
 + 
 +  * Read temperature data from the DS18B20 sensor. 
 +  * Apply simple logic to the temperature value. 
 +  * Turn an LED on or off based on a temperature condition. 
 +  * Connect the ESP32 to WiFi. 
 +  * Publish temperature readings to an MQTT topic. 
 +  * Subscribe to the MQTT topic in Node-RED. 
 +  * Convert or validate the incoming value in Node-RED. 
 +  * Store the temperature measurement in InfluxDB. 
 +  * Connect Grafana to InfluxDB. 
 +  * Create a Grafana dashboard showing the temperature data. 
 + 
 + 
 + 
 +====== Provided Resources ====== 
 + 
 +You may use the following resources during the evaluation: 
 + 
 +  * DS18B20 wiring schematic 
 +  * ESP32 pinout diagram 
 +  * MQTT topic structure example 
 +  * Node-RED flow reference diagram 
 +  * InfluxDB configuration notes 
 +  * Grafana dashboard setup notes 
 +  * Starter Arduino code 
 +  * Previous workshop code 
 +  * The workshop examples 
 +  * Internet search for syntax, library usage, and troubleshooting 
 + 
 +You are expected to understand and adapt the materials, not reproduce them from memory. 
 + 
 + 
 +====== Starter Code ====== 
 + 
 +The starter code gives you the basic structure of the program. 
 + 
 +**It does not contain the complete solution.** You must complete the missing parts and adapt the code to your own MQTT topic, pin choices, threshold value, and setup. 
 + 
 +<code cpp> 
 + 
 +#include <WiFi.h> 
 +#include <PubSubClient.h> 
 +#include <OneWire.h> 
 +#include <DallasTemperature.h> 
 + 
 +// TODO: Add WiFi credentials 
 +const char* SSID = "YOUR_WIFI_NAME"; 
 +const char* PASSWORD = "YOUR_WIFI_PASSWORD"; 
 + 
 +// TODO: Add MQTT broker address 
 +const char* MQTT_HOST = "YOUR_MQTT_BROKER_IP"; 
 +const int MQTT_PORT = 1234; 
 + 
 +// TODO: Define MQTT topic 
 +const char* MQTT_TOPIC = "workshop/student-name/temperature"; 
 + 
 +// TODO: Define pins 
 +#define ONE_WIRE_BUS 4 
 +#define LED_PIN 2 
 + 
 +WiFiClient wifi; 
 +PubSubClient mqtt(wifi); 
 + 
 +OneWire oneWire(ONE_WIRE_BUS); 
 +DallasTemperature temp_sensor(&oneWire); 
 + 
 +void setup_wifi() { 
 +  // TODO: Connect to WiFi 
 + 
 +  // TODO: Print connection status 
 + 
 +  // TODO: Print assigned IP address 
 +} 
 + 
 +void reconnect_mqtt() { 
 +  // TODO: Check MQTT connection 
 + 
 +  // TODO: Reconnect if disconnected 
 + 
 +  // TODO: Print MQTT connection status 
 +} 
 + 
 +void setup() { 
 +  Serial.begin(115200); 
 + 
 +  pinMode(LED_PIN, OUTPUT); 
 + 
 +  temp_sensor.begin(); 
 + 
 +  setup_wifi(); 
 + 
 +  mqtt.setServer(MQTT_HOST, MQTT_PORT); 
 +} 
 + 
 +void loop() { 
 +  if (!mqtt.connected()) { 
 +    reconnect_mqtt(); 
 +  } 
 + 
 +  mqtt.loop(); 
 + 
 +  // Request temperature from DS18B20 
 +  temp_sensor.requestTemperatures(); 
 + 
 +  // Read temperature in Celsius 
 +  float temperatureC = temp_sensor.getTempCByIndex(0); 
 + 
 +  // Check whether the reading is valid 
 +  if (temperatureC == DEVICE_DISCONNECTED_C) { 
 +    Serial.println("Error: DS18B20 sensor not detected or reading failed"); 
 +    delay(2000); 
 +    return; 
 +  } 
 + 
 +  // TODO: Print temperature to Serial Monitor 
 + 
 +  // TODO: Add LED threshold logic 
 + 
 +  // TODO: Convert temperature value to MQTT payload 
 + 
 +  // TODO: Publish temperature to MQTT topic 
 +}  
 +</code> 
 + 
 +===== Starter Code Expectations ===== 
 + 
 +Your final code should include: 
 + 
 +  * DS18B20 initialization 
 +  * Temperature reading in degrees Celsius 
 +  * Basic error handling for invalid sensor readings 
 +  * LED control based on a temperature threshold 
 +  * WiFi connection 
 +  * MQTT broker connection 
 +  * MQTT publishing 
 +  * Clear Serial Monitor output 
 +  * Basic comments explaining the main sections 
 + 
 +--- 
 + 
 +====== Hardware and Software ====== 
 + 
 +===== Hardware ===== 
 + 
 +The is the list of component that you need in order to complete this evaluation: 
 +  * ESP32 development board 
 +  * DS18B20 temperature sensor 
 +  * 4.7kΩ pull-up resistor 
 +  * Breadboard and jumper wires 
 +  * LED (use the built-in LED) 
 +  * 220Ω current-limiting resistor for LED 
 +  * USB cable 
 +  * Computer with PlatformIO 
 + 
 +===== Software and Services ===== 
 + 
 +  * VS Code with PlatformIO extension 
 +  * Required libraries, later on this page, you will be instructed to install them: 
 +    * OneWire 
 +    * DallasTemperature 
 +    * PubSubClient 
 +    * WiFi library for ESP32, which is already included 
 +  * MQTT broker 
 +  * Node-RED 
 +  * InfluxDB 
 +  * Grafana 
 + 
 +====== Practical Milestones, Requirements, and Deliverables ====== 
 + 
 +This section combines the required system behavior, the checkpoint structure, and the expected deliverables. 
 + 
 +Each milestone should be demonstrated before moving to the next layer of the IoT stack. 
 + 
 +The first milestone focuses only on the physical construction of the circuit. Students should not start debugging code before the sensor, resistors and ESP32 are correctly connected on the breadboard. 
 +===== Milestone 1: Physical Breadboard Connection of the DS18B20 and ESP32 ===== 
 + 
 +==== Required Behavior ==== 
 +{{ :inhabitat:kaunas:sensor-diagram.jpg?nolink&600 |}} 
 + 
 + 
 +1. The student must physically connect the **DS18B20 temperature sensor** to the **ESP32** using the breadboard. 
 + 
 +2. The circuit must include the required **4.7kΩ pull-up resistor** between the DS18B20 data line and the power line. 
 + 
 +At this stage, the focus is only on correct physical wiring. 
 + 
 +No sensor reading, WiFi connection, MQTT publishing, Node-RED flow, InfluxDB storage, or Grafana dashboard is required yet. 
 + 
 +==== Required Deliverables ==== 
 + 
 +You must show: 
 + 
 +  * ESP32 placed or connected correctly to the breadboard 
 +  * DS18B20 connected to the ESP32 
 +  * DS18B20 VCC connected to the correct voltage line 
 +  * DS18B20 GND connected to ground 
 +  * DS18B20 data pin connected to the selected ESP32 GPIO pin 
 +  * 4.7kΩ pull-up resistor connected between VCC and the DS18B20 data line 
 +  * LED connected to an ESP32 GPIO pin 
 +  * LED current-limiting resistor connected correctly 
 +  * Shared ground between all components 
 +  * Wiring that follows the provided schematic 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * They can identify the DS18B20 pins: VCC, GND, and DATA 
 +  * They can identify the ESP32 GPIO pin used for the DS18B20 data line 
 +  * They can explain the purpose of the 4.7kΩ pull-up resistor 
 +  * They can identify the GPIO pin used for the LED 
 +  * The breadboard wiring is organized enough to be inspected 
 +  * The circuit matches the provided schematic before code is uploaded 
 + 
 +==== Instructor Check ==== 
 + 
 +Before the student continues, the instructor should confirm: 
 + 
 +  * No power and ground lines are reversed 
 +  * The DS18B20 data line is not connected directly to VCC or GND 
 +  * The pull-up resistor is placed correctly 
 +  * The LED has a current-limiting resistor 
 +  * The ESP32, sensor, and LED share a common ground 
 + 
 + 
 + 
 +===== Milestone 2: DS18B20 Sensor Reading ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +The ESP32 must read temperature data from the DS18B20 sensor. 
 + 
 +The temperature value should be read in degrees Celsius. 
 + 
 +Example expected Serial Monitor output: 
 + 
 +<code> 
 +Temperature: 24.75 °C 
 +</code> 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * Arduino code that initializes the DS18B20 
 +  * Required DS18B20 libraries included 
 +  * Correct GPIO pin configured for the DS18B20 data line 
 +  * Temperature reading requested from the sensor 
 +  * Temperature value printed to the Serial Monitor 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * Temperature values appear in the Serial Monitor 
 +  * The values are realistic 
 +  * The code uses the same ESP32 GPIO pin as the physical circuit 
 +  * The student can explain the difference between connecting the sensor and reading the sensor in code 
 +  * The student can identify whether a problem is likely caused by wiring or code 
 + 
 + 
 +===== Milestone 3: Conditional Logic and LED Control ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +The ESP32 must apply a simple condition to the temperature value and control an LED based on that condition. 
 + 
 +Example condition: 
 + 
 +<code> 
 +If temperature is above 30°C, turn the LED on. 
 +Otherwise, turn the LED off. 
 +</code> 
 + 
 +Students may choose a different threshold, but the threshold must be clearly stated in the code comments or final explanation. 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * LED connected to the ESP32 
 +  * LED GPIO pin correctly defined in the Arduino code 
 +  * Temperature threshold implemented in the Arduino code 
 +  * LED turning on or off according to the condition 
 +  * Clear explanation of the chosen threshold 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * The LED responds to the temperature condition 
 +  * The condition is based on the DS18B20 reading 
 +  * The threshold value is visible in the code 
 +  * The student can explain why the LED turns on or off 
 +  * The student can distinguish between a sensor-reading issue and an LED-control issue 
 + 
 + 
 +===== Milestone 4: WiFi Connection and IP Address ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +The ESP32 must connect to the provided WiFi network. 
 + 
 +The device should print the assigned IP address to the Serial Monitor after connecting. 
 + 
 +Example expected Serial Monitor output: 
 + 
 +<code> 
 +Connected to WiFi 
 +IP address: 192.168.1.42 
 +</code> 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * WiFi credentials added to the Arduino code 
 +  * ESP32 successfully connected to WiFi 
 +  * IP address printed in the Serial Monitor 
 +  * Basic connection status messages 
 +  * Code structure that separates WiFi setup from the main loop 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * The ESP32 receives an IP address 
 +  * The Serial Monitor confirms WiFi connection 
 +  * The student can explain why WiFi is needed before MQTT can work 
 +  * The student can identify whether the ESP32 is connected to the network 
 + 
 +--- 
 + 
 +===== Milestone 5: MQTT Connection and Temperature Publishing ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +The ESP32 must publish the temperature value to an MQTT topic. 
 + 
 +Suggested topic format: 
 + 
 +<code> 
 +workshop/student-name/temperature 
 +</code> 
 + 
 +Example MQTT payload: 
 + 
 +<code> 
 +24.75 
 +</code> 
 + 
 +The payload should contain the temperature value as a number or a numeric string that can be processed in Node-RED. 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * MQTT broker address configured in the Arduino code 
 +  * MQTT topic configured in the Arduino code 
 +  * ESP32 connected to the MQTT broker 
 +  * Temperature values published to MQTT 
 +  * Serial Monitor output showing MQTT publishing activity 
 +  * Payload format suitable for Node-RED processing 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * The ESP32 connects to the MQTT broker 
 +  * Temperature values are published repeatedly 
 +  * The MQTT topic is clear and unique to the student or group 
 +  * The MQTT payload contains only the value or a clearly structured value 
 +  * The student can explain the difference between WiFi connection and MQTT connection 
 + 
 + 
 +===== Milestone 6: Node-RED MQTT Subscription and Value Processing ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +Create a Node-RED flow that receives the MQTT temperature data. 
 + 
 +The flow must: 
 + 
 +  * Subscribe to the MQTT topic. 
 +  * Receive the temperature value. 
 +  * Convert the incoming payload into a number if needed. 
 +  * Optionally check that the value is valid. 
 +  * Prepare the value for writing into InfluxDB. 
 + 
 +Recommended nodes: 
 + 
 +  * MQTT input node 
 +  * Debug node 
 +  * Function node or Change node for value conversion 
 +  * InfluxDB output node 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * Node-RED MQTT input node subscribed to the correct topic 
 +  * Debug output showing the incoming MQTT payload 
 +  * Node-RED logic that converts the payload into a number 
 +  * Processed value ready for InfluxDB 
 +  * Organized and readable Node-RED flow 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * MQTT messages from the ESP32 are visible in Node-RED 
 +  * The payload is converted from a string to a number if necessary 
 +  * The debug panel shows the processed value 
 +  * The student can explain the role of each node in the flow 
 + 
 + 
 +===== Milestone 7: Grafana Dashboard ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +Create a Grafana dashboard that visualizes the temperature data from InfluxDB. 
 + 
 +The dashboard should include at least one panel showing temperature over time. 
 + 
 +Recommended panel title: 
 + 
 +<code> 
 +DS18B20 Temperature Reading 
 +</code> 
 + 
 +The graph should update as new MQTT messages are published and stored. 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must show: 
 + 
 +  * InfluxDB configured as a Grafana datasource 
 +  * Query that retrieves the temperature data 
 +  * Dashboard panel displaying temperature over time 
 +  * Clear panel title 
 +  * Correct or appropriate unit, such as degrees Celsius 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * Grafana can access the InfluxDB datasource 
 +  * Temperature values appear in a dashboard panel 
 +  * The graph updates over time 
 +  * The student can explain how Grafana receives the data indirectly through InfluxDB 
 + 
 +===== Milestone 8: Final System Explanation ===== 
 + 
 +==== Required Behavior ==== 
 + 
 +The student must briefly explain the full data path: 
 + 
 +<code> 
 +DS18B20 → ESP32 → WiFi → MQTT → Node-RED → InfluxDB → Grafana 
 +</code> 
 + 
 +The explanation does not need to be long. It should show that the student understands what each part of the system does. 
 + 
 +==== Required Deliverables ==== 
 + 
 +The student or group must explain: 
 + 
 +  * What the DS18B20 measures 
 +  * How the DS18B20 is physically connected to the ESP32 
 +  * What the ESP32 does 
 +  * Why WiFi is needed 
 +  * What MQTT is used for 
 +  * What Node-RED does 
 +  * Why the data is stored in InfluxDB 
 +  * What Grafana displays 
 + 
 +==== Checkpoint Evidence ==== 
 + 
 +The student demonstrates that: 
 + 
 +  * They can describe the system from sensor to dashboard 
 +  * They can identify where a problem is happening in the stack 
 +  * They can distinguish between hardware, firmware, network, MQTT, Node-RED, database, and dashboard issues 
 +  * They can explain at least one troubleshooting step they used
  
inhabitat/kaunas/day04.1780003240.txt.gz · Last modified: 2026/05/28 23:20 by harley.lara