/*
  Session 2 — Core agricultural sensors (Arduino Uno — Tinkercad Circuits version)
  Tinkercad has no DHT22, so we use: TMP36 (air temperature) on A0, Soil Moisture Sensor on A1,
  Photoresistor (LDR) with a 10kΩ voltage divider on A2.  Real hardware version: s02_sensors_esp32
*/
const int TMP36_PIN = A0;
const int SOIL_PIN = A1;
const int LDR_PIN = A2;

// Manual 2-point calibration (session 2 lab): read the sensor in dry soil and in saturated soil
int SOIL_DRY = 0;     // Tinkercad soil sensor: 0 = dry ... ~876 = wet  (real capacitive sensors are inverted!)
int SOIL_WET = 876;

void setup() {
  Serial.begin(9600);
  Serial.println(F("temp_c,soil_raw,soil_pct,light_raw,light_pct"));   // CSV header -> paste into Excel
}

void loop() {
  // TMP36: 10 mV/°C with 500 mV offset  ->  T = (V - 0.5) * 100
  float v = analogRead(TMP36_PIN) * 5.0 / 1023.0;
  float tempC = (v - 0.5) * 100.0;

  int soilRaw = analogRead(SOIL_PIN);
  float soilPct = constrain((soilRaw - SOIL_DRY) * 100.0 / (SOIL_WET - SOIL_DRY), 0, 100);

  // LDR divider: more light -> lower LDR resistance -> higher voltage on A2 (LDR to 5V, 10k to GND)
  int lightRaw = analogRead(LDR_PIN);
  float lightPct = lightRaw * 100.0 / 1023.0;

  Serial.print(tempC, 1); Serial.print(',');
  Serial.print(soilRaw); Serial.print(',');
  Serial.print(soilPct, 0); Serial.print(',');
  Serial.print(lightRaw); Serial.print(',');
  Serial.println(lightPct, 0);

  if (soilPct < 30) Serial.println(F("# soil is dry -> irrigation recommended"));
  delay(2000);
}