ENS160_AHT21_Test.ino

/*
  ENS160 eCO2 Sensor with AHT21 T/H Sensor
  ens160.ino
  Reads TVOC/eCO2/AQI and compensates with AHT21 T/RH
  Requires SparkFun_ENS160 Library
  Requires Adafruit_AHTX0 Library
  Uses Seeeduino XIAO ESP32-S3, adjust pins for other ESP32
  
  DroneBot Workshop 2025
  https://dronebotworkshop.com
*/

// Include required libraries
#include <Wire.h>
#include "SparkFun_ENS160.h"
#include <Adafruit_AHTX0.h>

// I2C pins (adjust for different ESP32)
#define SDA_PIN 21  // XIAO D4
#define SCL_PIN 22  // XIAO D5

// Objects for ENS160 & AHT21
SparkFun_ENS160 ens;
Adafruit_AHTX0 aht;

// Output formatting
const uint8_t HEADER_EVERY = 12;  // reprint table header every N lines
uint8_t lineCount = 0;

// AQI Rating Function
const char* aqiText(uint8_t aqi) {
  switch (aqi) {
    case 1: return "Excellent";
    case 2: return "Good";
    case 3: return "Moderate";
    case 4: return "Poor";
    case 5: return "Unhealthy";
    default: return "?";
  }
}

// Ventilation Hint Function
const char* ventHint(uint16_t eco2_ppm) {
  if (eco2_ppm >= 1500) return "Ventilate now";
  if (eco2_ppm >= 1000) return "Consider ventilation";
  return "OK";
}

// Header Print Function
void printHeader() {
  Serial.println();
  Serial.println(F("+----------+---------+--------+-----------+-----------+-----+--------------+"));
  Serial.println(F("| Time (s) | Temp C  | RH  %  | TVOC ppb  | eCO2 ppm  | AQI | AQI (text)   |"));
  Serial.println(F("+----------+---------+--------+-----------+-----------+-----+--------------+"));
}

void setup() {
  // Start Serial Monitor
  Serial.begin(115200);
  delay(200);

  // Start I2C
  Wire.begin(SDA_PIN, SCL_PIN);
  Wire.setClock(400000);

  // Start ENS160 measurements
  if (!ens.begin()) {
    Serial.println("ENS160 not found (0x53/0x52). Check wiring/ADD pin.");
    while (1) delay(100);
  }
  ens.setOperatingMode(SFE_ENS160_STANDARD);

  // Start AHT21
  if (!aht.begin()) {
    Serial.println("AHT21 not found (0x38). Check wiring.");
    while (1) delay(100);
  }

  Serial.println(F("ENS160 + AHT21 ready. ENS160 needs a short warm-up for stable readings."));
  printHeader();
}

void loop() {
  // Read AHT21 T/RH for display (and to show alongside ENS160 data)
  sensors_event_t humidity, temp;
  aht.getEvent(&humidity, &temp);
  float tC = temp.temperature;
  float rh = humidity.relative_humidity;

  // When ENS160 data is ready (about once per second), print a row
  if (ens.checkDataStatus()) {
    uint8_t aqi = ens.getAQI();     // 1..5
    uint16_t tvoc = ens.getTVOC();  // ppb
    uint16_t eco2 = ens.getECO2();  // ppm (equivalent; VOC-derived)

    if (lineCount % HEADER_EVERY == 0) printHeader();

    // Row
    Serial.printf("| %8lu | %7.2f | %6.1f | %9u | %9u |  %u  | %-12s |\n",
                  millis() / 1000UL, tC, rh, tvoc, eco2, aqi, aqiText(aqi));

    // One-line hint (eCO2 is an estimate)
    Serial.printf("  Note: AQI=%u (%s), eCO2=%u ppm → %s (eCO2 is estimated)\n\n",
                  aqi, aqiText(aqi), eco2, ventHint(eco2));

    lineCount++;
  }

  delay(200);
}