The Tiger Sensor: A Continuous WBGT Monitor

This project includes instructions and code for a wet bulb globe temperature monitor. It continuously takes in data and links it to a website to visualize.

Mar 17, 2026

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GPL3+

Data Collection

Environmental Sensing

Monitoring

Devices & Components

10 jumper wires 150mm male

40 colored male-female jumper wires

Arduino® UNO R4 WiFi

Breadboard - 400 contacts

Black Ping Pong Ball

DS18B20 Temperature Probe

Mini Solar Panel 6V

Solar Power Manager Module

DHT22 Temp and Humidity Sensor

18650 Lithium Battery

Hardware & Tools

Electronics Soldering Iron

Software & Tools

Arduino IDE

Creality Cloud

Project description

Code

WBGT connected to website

cpp

Code for connecting the WBGT monitor to a website

1#include <DHT.h> 
2#include <Wire.h> 
3#include <LiquidCrystal_I2C.h> 
4#include <OneWire.h> 
5#include <DallasTemperature.h> 
6#include <RTClib.h> 
7#include <WiFiS3.h> 
8#include <ArduinoHttpClient.h> 
9#include <ArduinoJson.h> 
10
11// -------------------- Pin Definitions -------------------- 
12#define DHTPIN 2 
13#define DHTTYPE DHT22 
14#define ONE_WIRE_BUS 8 
15
16// -------------------- WiFi & API Settings -------------------- 
17const char* WIFI_SSID     = "WiFi Name"; //write wifi name here
18const char* WIFI_PASSWORD = "WiFi Passowrd"; //write wifi password here
19const char* SUPABASE_HOST = "iqxjjdbhqlpobreotjcp.supabase.co"; 
20const char* SENSOR_ID     = "Sensor ID"; //paste in sensor ID here
21const char* API_KEY       = "sb_publishable_cm1u3V60C8JKuF2qBybrIg_BIOzopRf"; // <-- replace with your anon key 
22
23// -------------------- Objects -------------------- 
24DHT dht(DHTPIN, DHTTYPE); 
25OneWire oneWire(ONE_WIRE_BUS); 
26DallasTemperature globeSensor(&oneWire); 
27LiquidCrystal_I2C lcd(0x27, 16, 2); 
28RTC_DS1307 rtc; 
29WiFiSSLClient wifi; 
30HttpClient client = HttpClient(wifi, SUPABASE_HOST, 443); 
31
32bool rtcAvailable = false; 
33
34// -------------------- Functions -------------------- 
35float wetBulb(float Ta, float RH) { 
36  return Ta * atan(0.151977 * sqrt(RH + 8.313659)) 
37       + atan(Ta + RH) 
38       - atan(RH - 1.676331) 
39       + 0.00391838 * pow(RH, 1.5) * atan(0.023101 * RH) 
40       - 4.686035; 
41} 
42
43float CtoF(float C) { 
44  return (C * 9.0 / 5.0) + 32.0; 
45} 
46
47String heatRiskF(float WBGT_F) { 
48  if (WBGT_F < 82.4) return "Safe"; 
49  else if (WBGT_F < 89.4) return "Caution"; 
50  else if (WBGT_F < 94.8) return "Extreme"; 
51  else if (WBGT_F < 100.4) return "Danger"; 
52  else return "Extreme"; 
53} 
54
55void connectWiFi() { 
56  Serial.print("Connecting to WiFi..."); 
57  lcd.clear(); 
58  lcd.setCursor(0, 0); 
59  lcd.print("Connecting WiFi"); 
60  WiFi.begin(WIFI_SSID, WIFI_PASSWORD); 
61  int attempts = 0; 
62  while (WiFi.status() != WL_CONNECTED && attempts < 40) { 
63    delay(500); 
64    Serial.print("."); 
65    attempts++; 
66  } 
67
68  if (WiFi.status() == WL_CONNECTED) { 
69    Serial.println(" Connected!"); 
70    lcd.setCursor(0, 1); 
71    lcd.print("WiFi Connected!"); 
72  } else { 
73    Serial.println(" WiFi Failed!"); 
74    lcd.setCursor(0, 1); 
75    lcd.print("WiFi Failed!"); 
76  } 
77  delay(2000); 
78} 
79
80// -------------------- Send Data to Supabase Table -------------------- 
81void sendToWebsite(float TaC, float RH, float TgC, float TwbC, float WBGT_C, String risk) { 
82  if (WiFi.status() != WL_CONNECTED) { 
83    connectWiFi(); 
84  } 
85
86  StaticJsonDocument<512> doc; 
87  doc["sensor_id"]  = SENSOR_ID; 
88  doc["dry_bulb"]   = TaC; 
89  doc["humidity"]   = RH; 
90  doc["globe_temp"] = TgC; 
91  doc["wet_bulb"]   = TwbC; 
92  doc["wbgt"]       = WBGT_C; 
93
94  String payload; 
95  serializeJson(doc, payload); 
96
97  Serial.println("Sending data to Supabase table..."); 
98  Serial.println(payload); 
99
100  String bearerToken = "Bearer "; 
101  bearerToken += API_KEY; 
102
103  client.beginRequest(); 
104  client.post("/rest/v1/sensor_readings");  
105  client.sendHeader("Content-Type", "application/json"); 
106  client.sendHeader("apikey", API_KEY); 
107  client.sendHeader("Authorization", bearerToken); 
108  client.sendHeader("Prefer", "return=representation"); 
109  client.sendHeader("Content-Length", payload.length()); 
110  client.beginBody(); 
111  client.print(payload); 
112  client.endRequest(); 
113
114  int statusCode = client.responseStatusCode(); 
115  String response = client.responseBody(); 
116  Serial.print("Server response: "); 
117  Serial.println(statusCode); 
118  Serial.println(response); 
119
120  lcd.clear(); 
121  lcd.setCursor(0, 0); 
122  if (statusCode == 201) { 
123    lcd.print("Data Sent OK!"); 
124  } else { 
125    lcd.print("Send Failed:"); 
126    lcd.setCursor(0, 1); 
127    lcd.print("Code: "); 
128    lcd.print(statusCode); 
129  } 
130 delay(2000); 
131} 
132
133// -------------------- Setup -------------------- 
134void setup() { 
135  Serial.begin(9600); 
136  delay(2000); 
137  Wire.begin(); 
138
139  dht.begin(); 
140  globeSensor.begin(); 
141  lcd.init(); 
142  lcd.backlight(); 
143
144  if (!rtc.begin()) { 
145    Serial.println("RTC not found - continuing anyway"); 
146    lcd.clear(); 
147    lcd.print("RTC Error"); 
148    delay(2000); 
149  } else { 
150    rtcAvailable = true; 
151    if (!rtc.isrunning()) { 
152      rtc.adjust(DateTime(F(__DATE__), F(__TIME__))); 
153    } 
154  } 
155
156  lcd.clear(); 
157  lcd.setCursor(0, 0); 
158  lcd.print("Team 6"); 
159  lcd.setCursor(0, 1); 
160  lcd.print("WBGT Monitor"); 
161  delay(2000); 
162  lcd.clear(); 
163
164  connectWiFi(); 
165  lcd.clear(); 
166} 
167
168// -------------------- Loop -------------------- 
169void loop() { 
170  float TaC = dht.readTemperature(); 
171  float RH  = dht.readHumidity(); 
172
173  globeSensor.requestTemperatures(); 
174  float TgC = globeSensor.getTempCByIndex(0); 
175
176  if (isnan(TaC) || isnan(RH) || TgC == DEVICE_DISCONNECTED_C) { 
177    lcd.clear(); 
178    lcd.print("Sensor Error"); 
179    Serial.println("Sensor read error!"); 
180    delay(2000); 
181    return; 
182  } 
183
184  float TwbC   = wetBulb(TaC, RH); 
185  float WBGT_C = 0.7 * TwbC + 0.2 * TgC + 0.1 * TaC; 
186  float TaF    = CtoF(TaC); 
187  float TgF    = CtoF(TgC); 
188  float TwbF   = CtoF(TwbC); 
189  float WBGT_F = CtoF(WBGT_C); 
190  String risk  = heatRiskF(WBGT_F); 
191
192  // -------------------- LCD Screen 1 -------------------- 
193  lcd.clear(); 
194  lcd.setCursor(0, 0); 
195  lcd.print("WBGT:"); 
196  lcd.print(WBGT_F, 1); 
197  lcd.print("F"); 
198  lcd.setCursor(0, 1); 
199  lcd.print(risk); 
200  delay(15000); // show for 15 seconds
201
202  // -------------------- LCD Screen 2 -------------------- 
203  lcd.clear(); 
204  lcd.setCursor(0, 0); 
205  lcd.print("Twb:"); 
206  lcd.print(TwbF, 1); 
207  lcd.print(" Tg:"); 
208  lcd.print(TgF, 1); 
209  lcd.setCursor(0, 1); 
210  lcd.print("Ta:"); 
211  lcd.print(TaF, 1); 
212  lcd.print(" RH:"); 
213  lcd.print(RH, 0); 
214  lcd.print("%"); 
215  delay(15000); // show for 15 seconds
216
217  // -------------------- LCD Screen 3 (RTC) -------------------- 
218  if (rtcAvailable) { 
219    DateTime now = rtc.now(); 
220    lcd.clear(); 
221    lcd.setCursor(0, 0); 
222    lcd.print(now.month()); lcd.print("/"); 
223    lcd.print(now.day());   lcd.print("/"); 
224    lcd.print(now.year()); 
225    lcd.setCursor(0, 1); 
226    if (now.hour() < 10) lcd.print("0"); 
227    lcd.print(now.hour()); lcd.print(":"); 
228    if (now.minute() < 10) lcd.print("0"); 
229    lcd.print(now.minute()); lcd.print(":"); 
230    if (now.second() < 10) lcd.print("0"); 
231    lcd.print(now.second()); 
232    delay(5000); // 
233  } 
234
235  // -------------------- Send to Supabase Table (Celsius) -------------------- 
236  sendToWebsite(TaC, RH, TgC, TwbC, WBGT_C, risk); 
237}

#include <DHT.h> 
#include <Wire.h> 
#include <LiquidCrystal_I2C.h> 
#include <OneWire.h> 
#include <DallasTemperature.h> 
#include <RTClib.h> 
#include <WiFiS3.h> 
#include <ArduinoHttpClient.h> 
#include <ArduinoJson.h> 

// -------------------- Pin Definitions -------------------- 
#define DHTPIN 2 
#define DHTTYPE DHT22 
#define ONE_WIRE_BUS 8 

// -------------------- WiFi & API Settings -------------------- 
const char* WIFI_SSID     = "WiFi Name"; //write wifi name here
const char* WIFI_PASSWORD = "WiFi Passowrd"; //write wifi password here
const char* SUPABASE_HOST = "iqxjjdbhqlpobreotjcp.supabase.co"; 
const char* SENSOR_ID     = "Sensor ID"; //paste in sensor ID here
const char* API_KEY       = "sb_publishable_cm1u3V60C8JKuF2qBybrIg_BIOzopRf"; // <-- replace with your anon key 

// -------------------- Objects -------------------- 
DHT dht(DHTPIN, DHTTYPE); 
OneWire oneWire(ONE_WIRE_BUS); 
DallasTemperature globeSensor(&oneWire); 
LiquidCrystal_I2C lcd(0x27, 16, 2); 
RTC_DS1307 rtc; 
WiFiSSLClient wifi; 
HttpClient client = HttpClient(wifi, SUPABASE_HOST, 443); 

bool rtcAvailable = false; 

// -------------------- Functions -------------------- 
float wetBulb(float Ta, float RH) { 
  return Ta * atan(0.151977 * sqrt(RH + 8.313659)) 
       + atan(Ta + RH) 
       - atan(RH - 1.676331) 
       + 0.00391838 * pow(RH, 1.5) * atan(0.023101 * RH) 
       - 4.686035; 
} 

float CtoF(float C) { 
  return (C * 9.0 / 5.0) + 32.0; 
} 

String heatRiskF(float WBGT_F) { 
  if (WBGT_F < 82.4) return "Safe"; 
  else if (WBGT_F < 89.4) return "Caution"; 
  else if (WBGT_F < 94.8) return "Extreme"; 
  else if (WBGT_F < 100.4) return "Danger"; 
  else return "Extreme"; 
} 

void connectWiFi() { 
  Serial.print("Connecting to WiFi..."); 
  lcd.clear(); 
  lcd.setCursor(0, 0); 
  lcd.print("Connecting WiFi"); 
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD); 
  int attempts = 0; 
  while (WiFi.status() != WL_CONNECTED && attempts < 40) { 
    delay(500); 
    Serial.print("."); 
    attempts++; 
  } 

  if (WiFi.status() == WL_CONNECTED) { 
    Serial.println(" Connected!"); 
    lcd.setCursor(0, 1); 
    lcd.print("WiFi Connected!"); 
  } else { 
    Serial.println(" WiFi Failed!"); 
    lcd.setCursor(0, 1); 
    lcd.print("WiFi Failed!"); 
  } 
  delay(2000); 
} 

// -------------------- Send Data to Supabase Table -------------------- 
void sendToWebsite(float TaC, float RH, float TgC, float TwbC, float WBGT_C, String risk) { 
  if (WiFi.status() != WL_CONNECTED) { 
    connectWiFi(); 
  } 

  StaticJsonDocument<512> doc; 
  doc["sensor_id"]  = SENSOR_ID; 
  doc["dry_bulb"]   = TaC; 
  doc["humidity"]   = RH; 
  doc["globe_temp"] = TgC; 
  doc["wet_bulb"]   = TwbC; 
  doc["wbgt"]       = WBGT_C; 

  String payload; 
  serializeJson(doc, payload); 

  Serial.println("Sending data to Supabase table..."); 
  Serial.println(payload); 

  String bearerToken = "Bearer "; 
  bearerToken += API_KEY; 

  client.beginRequest(); 
  client.post("/rest/v1/sensor_readings");  
  client.sendHeader("Content-Type", "application/json"); 
  client.sendHeader("apikey", API_KEY); 
  client.sendHeader("Authorization", bearerToken); 
  client.sendHeader("Prefer", "return=representation"); 
  client.sendHeader("Content-Length", payload.length()); 
  client.beginBody(); 
  client.print(payload); 
  client.endRequest(); 

  int statusCode = client.responseStatusCode(); 
  String response = client.responseBody(); 
  Serial.print("Server response: "); 
  Serial.println(statusCode); 
  Serial.println(response); 

  lcd.clear(); 
  lcd.setCursor(0, 0); 
  if (statusCode == 201) { 
    lcd.print("Data Sent OK!"); 
  } else { 
    lcd.print("Send Failed:"); 
    lcd.setCursor(0, 1); 
    lcd.print("Code: "); 
    lcd.print(statusCode); 
  } 
 delay(2000); 
} 

// -------------------- Setup -------------------- 
void setup() { 
  Serial.begin(9600); 
  delay(2000); 
  Wire.begin(); 

  dht.begin(); 
  globeSensor.begin(); 
  lcd.init(); 
  lcd.backlight(); 

  if (!rtc.begin()) { 
    Serial.println("RTC not found - continuing anyway"); 
    lcd.clear(); 
    lcd.print("RTC Error"); 
    delay(2000); 
  } else { 
    rtcAvailable = true; 
    if (!rtc.isrunning()) { 
      rtc.adjust(DateTime(F(__DATE__), F(__TIME__))); 
    } 
  } 

  lcd.clear(); 
  lcd.setCursor(0, 0); 
  lcd.print("Team 6"); 
  lcd.setCursor(0, 1); 
  lcd.print("WBGT Monitor"); 
  delay(2000); 
  lcd.clear(); 

  connectWiFi(); 
  lcd.clear(); 
} 

// -------------------- Loop -------------------- 
void loop() { 
  float TaC = dht.readTemperature(); 
  float RH  = dht.readHumidity(); 

  globeSensor.requestTemperatures(); 
  float TgC = globeSensor.getTempCByIndex(0); 

  if (isnan(TaC) || isnan(RH) || TgC == DEVICE_DISCONNECTED_C) { 
    lcd.clear(); 
    lcd.print("Sensor Error"); 
    Serial.println("Sensor read error!"); 
    delay(2000); 
    return; 
  } 

  float TwbC   = wetBulb(TaC, RH); 
  float WBGT_C = 0.7 * TwbC + 0.2 * TgC + 0.1 * TaC; 
  float TaF    = CtoF(TaC); 
  float TgF    = CtoF(TgC); 
  float TwbF   = CtoF(TwbC); 
  float WBGT_F = CtoF(WBGT_C); 
  String risk  = heatRiskF(WBGT_F); 

  // -------------------- LCD Screen 1 -------------------- 
  lcd.clear(); 
  lcd.setCursor(0, 0); 
  lcd.print("WBGT:"); 
  lcd.print(WBGT_F, 1); 
  lcd.print("F"); 
  lcd.setCursor(0, 1); 
  lcd.print(risk); 
  delay(15000); // show for 15 seconds

  // -------------------- LCD Screen 2 -------------------- 
  lcd.clear(); 
  lcd.setCursor(0, 0); 
  lcd.print("Twb:"); 
  lcd.print(TwbF, 1); 
  lcd.print(" Tg:"); 
  lcd.print(TgF, 1); 
  lcd.setCursor(0, 1); 
  lcd.print("Ta:"); 
  lcd.print(TaF, 1); 
  lcd.print(" RH:"); 
  lcd.print(RH, 0); 
  lcd.print("%"); 
  delay(15000); // show for 15 seconds

  // -------------------- LCD Screen 3 (RTC) -------------------- 
  if (rtcAvailable) { 
    DateTime now = rtc.now(); 
    lcd.clear(); 
    lcd.setCursor(0, 0); 
    lcd.print(now.month()); lcd.print("/"); 
    lcd.print(now.day());   lcd.print("/"); 
    lcd.print(now.year()); 
    lcd.setCursor(0, 1); 
    if (now.hour() < 10) lcd.print("0"); 
    lcd.print(now.hour()); lcd.print(":"); 
    if (now.minute() < 10) lcd.print("0"); 
    lcd.print(now.minute()); lcd.print(":"); 
    if (now.second() < 10) lcd.print("0"); 
    lcd.print(now.second()); 
    delay(5000); // 
  } 

  // -------------------- Send to Supabase Table (Celsius) -------------------- 
  sendToWebsite(TaC, RH, TgC, TwbC, WBGT_C, risk); 
}

Downloadable files

Base Layer

Monitor Case

BaseLayer.stl

Layer 1

Monitor Case

Layer1.stl

Layer 2

Monitor Case

Layer2.stl

Layer 3

Monitor Case

Layer3.stl

Layer 4

Monitor Case

Layer4.stl

Layer 5

Monitor Case

Layer5.stl

Layer 6

Monitor Case

Layer6.stl

Roof

Monitor Case

Roof.stl

Documentation

Tiger Sensor Guidance Package

Informational document for producing the monitor

Tiger Sensor Guidance Package.pdf

Monitor Schematic

Schematic of the monitor connections

Schematic.png

Breadboard View

Breadboard view of the monitor connections

Breadboard.png

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