ESP32 UV Index Monitor

// ESP32 UV Index Monitor - Intermediate (SED dose accumulator + Telegram alert)
// SED = Standard Erythemal Dose; 1 SED = 100 J/m2 erythemally weighted UV
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_VEML6075.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include <Preferences.h>
#include <time.h>

Adafruit_SSD1306 oled(128,64,&Wire,-1);
Adafruit_VEML6075 uv;
Preferences prefs;

const char* SSID="YourSSID", *PASS="YourPass";
const char* BOT_TOKEN="YOUR_BOT_TOKEN";
const char* CHAT_ID="YOUR_CHAT_ID";

// Skin type MED (Minimal Erythema Dose) in SED — Fitzpatrick scale I-VI
// Lower MED = more UV-sensitive skin
const float MED_SED[] = {2.0f, 2.5f, 3.5f, 4.5f, 6.0f, 8.0f};
const int SKIN_TYPE = 2; // 0=type I (very fair), 5=type VI (dark)
float dailyDose_SED = 0;
bool alertSent = false;
int lastDay = -1;

float sedPerSecond(float uvi){
  // Approximate: 1 UV Index unit ~ 0.025 W/m2 erythemal irradiance
  // 1 SED = 100 J/m2; so dose rate in SED/s = uvi*0.025/100
  return uvi * 0.00025f;
}

void sendTelegram(const String &msg){
  WiFiClientSecure c; c.setInsecure();
  if(!c.connect("api.telegram.org",443)) return;
  String body="chat_id="+String(CHAT_ID)+"&text="+msg;
  c.printf("POST /bot%s/sendMessage HTTP/1.1rnHost: api.telegram.orgrn"
    "Content-Type: application/x-www-form-urlencodedrnContent-Length: %drnrn%s",
    BOT_TOKEN,(int)body.length(),body.c_str());
  delay(1000); c.stop();
}

void setup(){
  Serial.begin(115200);
  Wire.begin(21,22);
  oled.begin(SSD1306_SWITCHCAPVCC,0x3C); oled.setTextColor(WHITE);
  uv.begin();
  WiFi.begin(SSID,PASS);
  while(WiFi.status()!=WL_CONNECTED) delay(500);
  configTime(0,0,"pool.ntp.org");
  prefs.begin("uv",false);
  dailyDose_SED=prefs.getFloat("dose",0);
  prefs.end();
}

unsigned long lastMs=0;
void loop(){
  struct tm ti; getLocalTime(&ti);
  if(ti.tm_mday!=lastDay){ dailyDose_SED=0; alertSent=false; lastDay=ti.tm_mday; }

  unsigned long now=millis();
  float dt=(now-lastMs)/1000.0f; lastMs=now;
  float uvi=uv.readUVI();
  if(uvi>0) dailyDose_SED += sedPerSecond(uvi)*dt;

  float med=MED_SED[SKIN_TYPE];
  float pct=dailyDose_SED/med*100.0f;
  Serial.printf("UVI: %.1f  Dose: %.3f SED  MED: %.0f%%n",uvi,dailyDose_SED,pct);

  if(pct>=80&&!alertSent){
    sendTelegram("UV ALERT: "+String((int)pct)+"% of daily safe dose reached! UVI="+String(uvi,1));
    alertSent=true;
  }

  prefs.begin("uv",false); prefs.putFloat("dose",dailyDose_SED); prefs.end();

  oled.clearDisplay(); oled.setCursor(0,0); oled.setTextSize(1);
  oled.printf("UVI: %.1fn",uvi);
  oled.printf("Dose: %.2f / %.1f SEDn",dailyDose_SED,med);
  oled.printf("MED used: %.0f%%n",pct);
  oled.println(pct>=100?"STAY INDOORS":pct>=80?"SEEK SHADE":"Safe");
  oled.display();
  delay(5000);
}