Current version from old git. Release 0.0.9

.gitignore

+.pioenvs
+.pio/libdeps
+.pio/build
+.vscode
+*.ino.cpp
+config.h
+config.hftstuttgart.h
+.project
+.cproject
+.settings

Ampel.h

+#ifndef AMPEL_H_INCLUDED
+#define AMPEL_H_INCLUDED
+/*****************************************************************
+ * Libraries                                                     *
+ *****************************************************************/
+#include "config.h"
+#ifndef MEASUREMENT_TIMESTEP
+#  error Missing config.h file. Please copy config.example.h to config.h.
+#endif
+#ifdef MQTT
+#  include "mqtt.h"
+#endif
+
+#include "util.h"
+#include "wifi_util.h"
+#include "co2_sensor.h"
+
+#ifdef HTTP
+#  include "web_server.h"
+#endif
+
+#include "led_effects.h"
+#include "csv_writer.h"
+
+#if defined(ESP8266)
+//allows sensor to be seen as SENSOR_ID.local, from the local network. For example : espd05cc9.local
+#  include <ESP8266mDNS.h>
+#elif defined(ESP32)
+#  include <ESPmDNS.h>
+#endif
+
+void keepServicesAlive();
+void checkFlashButton();
+
+#endif

Ampel.ino

+/***
+ *       ____ ___ ____       _                         _
+ *      / ___/ _ \___ \     / \   _ __ ___  _ __   ___| |
+ *     | |  | | | |__) |   / _ \ | '_ ` _ \| '_ \ / _ \ |
+ *     | |__| |_| / __/   / ___ \| | | | | | |_) |  __/ |
+ *      \____\___/_____| /_/__ \_\_| |_| |_| .__/ \___|_|         _
+ *     | | | |/ _|_   _| / ___|| |_ _   _| |_| |_ __ _  __ _ _ __| |_
+ *     | |_| | |_  | |   \___ \| __| | | | __| __/ _` |/ _` | '__| __|
+ *     |  _  |  _| | |    ___) | |_| |_| | |_| || (_| | (_| | |  | |_
+ *     |_| |_|_|   |_|   |____/ \__|\__,_|\__|\__\__, |\__,_|_|   \__|
+ *                                               |___/
+ */
+
+#include "Ampel.h"
+
+/*****************************************************************
+ * GPL License                                                   *
+ *****************************************************************/
+/*
+ * This file is part of the "CO2 Ampel" project (https://gitlab.rz.hft-stuttgart.de/otto/hft-stuttgart_co2_ampel)
+ * Copyright (c) 2020 HfT Stuttgart.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/*****************************************************************
+ * Authors                                                       *
+ *****************************************************************/
+/*
+ * Eric Duminil
+ * Robert Otto
+ * Myriam Guedey
+ * Tobias Gabriel Erhart
+ * Jonas Stave
+ */
+
+/*****************************************************************
+ * Configuration                                                 *
+ *****************************************************************/
+/*
+ * Please define settings in 'config.h'.
+ * There's an example config file called 'config.example.h'.
+ * You can copy 'config.public.h' (stored in Git) to 'config.h' (not stored in Git),
+ * and define your credentials and parameters in 'config.h'.
+ */
+
+/*****************************************************************
+ * Setup                                                         *
+ *****************************************************************/
+void setup() {
+  LedEffects::setupOnBoardLED();
+  LedEffects::onBoardLEDOff();
+
+  Serial.begin(BAUDS);
+
+  pinMode(0, INPUT);  // Flash button (used for forced calibration)
+
+  LedEffects::setupRing();
+
+  sensor::initialize();
+
+  Serial.print(F("Sensor ID: "));
+  Serial.println(SENSOR_ID);
+  Serial.print(F("Board    : "));
+  Serial.println(BOARD);
+
+  // Try to connect to Wi-Fi
+  WiFiConnect(SENSOR_ID);
+
+  Serial.print(F("WiFi STATUS: "));
+  Serial.println(WiFi.status());
+
+  if (WiFi.status() == WL_CONNECTED) {
+#ifdef HTTP
+    web_server::initialize();
+#endif
+
+    ntp::initialize();
+
+    if (MDNS.begin(SENSOR_ID.c_str())) { // Start the mDNS responder for SENSOR_ID.local
+      MDNS.addService("http", "tcp", 80);
+      Serial.println(F("mDNS responder started"));
+    } else {
+      Serial.println(F("Error setting up MDNS responder!"));
+    }
+
+#ifdef MQTT
+    mqtt::initialize("CO2sensors/" + SENSOR_ID);
+#endif
+  }
+  csv_writer::initialize();
+}
+
+/*****************************************************************
+ * Main loop                                                     *
+ *****************************************************************/
+
+void loop() {
+  //NOTE: Loop should never take more than 1000ms. Split in smaller methods and logic if needed.
+  //TODO: Restart every day or week, in order to not let t0 overflow?
+  uint32_t t0 = millis();
+
+  /**
+   * USER INTERACTION
+   */
+  keepServicesAlive();
+  // Short press for night mode, Long press for calibration.
+  checkFlashButton();
+
+  /**
+   * GET DATA
+   */
+  bool freshData = sensor::scd30.dataAvailable(); // Alternative : close to time-step AND dataAvailable, to avoid asking the sensor too often.
+
+  if (freshData) {
+    sensor::co2 = sensor::scd30.getCO2();
+    sensor::temperature = sensor::scd30.getTemperature();
+    sensor::humidity = sensor::scd30.getHumidity();
+  }
+
+  //NOTE: Data is available, but it's sometimes erroneous: the sensor outputs zero ppm but non-zero temperature and non-zero humidity.
+  if (sensor::co2 <= 0) {
+    // No measurement yet. Waiting.
+    LedEffects::showWaitingLED(color::blue);
+    return;
+  }
+
+  /**
+   * Fresh data. Show it and send it if needed.
+   */
+
+  if (freshData) {
+    sensor::timestamp = ntp::getLocalTime();
+    Serial.println(sensor::timestamp);
+
+    Serial.print(F("co2(ppm): "));
+    Serial.print(sensor::co2);
+    Serial.print(F(" temp(C): "));
+    Serial.print(sensor::temperature);
+    Serial.print(F(" humidity(%): "));
+    Serial.println(sensor::humidity);
+
+    csv_writer::logIfTimeHasCome(sensor::timestamp, sensor::co2, sensor::temperature, sensor::humidity);
+
+#ifdef MQTT
+    mqtt::publishIfTimeHasCome(sensor::timestamp, sensor::co2, sensor::temperature, sensor::humidity);
+#endif
+  }
+
+  if (sensor::co2 < 250) {
+    // Sensor should be calibrated.
+    LedEffects::showWaitingLED(color::magenta);
+    return;
+  }
+
+  /**
+   * Display data, even if it's "old" (with breathing).
+   * Those effects include a short delay.
+   */
+
+  if (sensor::co2 < 2000) {
+    LedEffects::displayCO2color(sensor::co2);
+    LedEffects::breathe(sensor::co2);
+  } else {  // >= 2000: entire ring blinks red
+    LedEffects::redAlert();
+  }
+
+  uint32_t duration = millis() - t0;
+  if (duration > max_loop_duration) {
+    max_loop_duration = duration;
+    Serial.print("Max loop duration : ");
+    Serial.print(max_loop_duration);
+    Serial.println(" ms.");
+  }
+}
+
+/**
+ * Checks if flash button has been pressed:
+ *   If not, do nothing.
+ *   If short press, toggle LED display.
+ *   If long press, start calibration process.
+ */
+void checkFlashButton() {
+  if (!digitalRead(0)) { // Button has been pressed
+    LedEffects::onBoardLEDOn();
+    delay(300);
+    if (digitalRead(0)) {
+      Serial.println(F("Flash has been pressed for a short time. Should toggle night mode."));
+      LedEffects::toggleNightMode();
+    } else {
+      Serial.println(F("Flash has been pressed for a long time. Keep it pressed for calibration."));
+      if (LedEffects::countdownToZero() < 0) {
+        sensor::startCalibrationProcess();
+      }
+    }
+    LedEffects::onBoardLEDOff();
+  }
+}
+
+void keepServicesAlive() {
+  if (WiFi.status() == WL_CONNECTED) {
+#if defined(ESP8266)
+    //NOTE: Sadly, there seems to be a bug in the current MDNS implementation.
+    // It stops working after 2 minutes. And forcing a restart leads to a memory leak.
+    MDNS.update();
+#endif
+    ntp::update(); // NTP client has its own timer. It will connect to NTP server every 60s.
+#ifdef HTTP
+    web_server::update();
+#endif
+#ifdef MQTT
+    mqtt::keepConnection(); // MQTT client has its own timer. It will keep alive every 15s.
+#endif
+  }
+}

Makefile

+all:
+	pio -f -c vim run
+
+upload:
+	pio -f -c vim run --target upload -e $(board)
+
+clean:
+	pio -f -c vim run --target clean
+
+program:
+	pio -f -c vim run --target program
+
+uploadfs:
+	pio -f -c vim run --target uploadfs
+
+update:
+	pio -f -c vim update
+
+monitor:
+	pio device monitor --filter colorize

README.md

+# CO<sub>2</sub> Ampel
+
+*CO<sub>2</sub> Ampel* is an open-source project, written in C++ for ESP8266 or ESP32.
+
+It measures the current CO<sub>2</sub> concentration (in ppm), and displays it on an LED ring.
+
+The room should be ventilated as soon as one LED turns red.
+
+## Hardware Requirements
+
+* [ESP8266](https://en.wikipedia.org/wiki/ESP8266) or [ESP32](https://en.wikipedia.org/wiki/ESP32) microcontroller (this project has been tested with *ESP8266 ESP-12 WIFI* and *TTGO ESP32 SX1276 LoRa*)
+* [Sensirion SCD30](https://www.sensirion.com/en/environmental-sensors/carbon-dioxide-sensors/carbon-dioxide-sensors-co2/) "Sensor Module for HVAC and Indoor Air Quality Applications"
+* [NeoPixel Ring - 12](https://www.adafruit.com/product/1643)
+
+## Software Requirements
+
+* [PlatformIO](https://platformio.org/)
+or
+* [Arduino IDE](https://www.arduino.cc/en/software)
+
+## Installation
+
+* If `config.h` does not exist, copy it from `config.public.h`
+* Modify `config.h`, e.g. for measurement time-steps, WiFi access, MQTT, NTP and web-server.
+
+### PlatformIO
+
+PlatformIO can be run from [VSCODE](https://platformio.org/install/ide?install=vscode), [Eclipse CDT](https://www.eclipse.org/cdt/) or console:
+
+```bash
+make upload board=esp8266 && make monitor # For ESP8266
+```
+```bash
+make upload board=esp32 && make monitor # For ESP32
+```
+
+### Arduino IDE
+
+* All the libraries are included in this repository. No need to install anything via *Library Manager*.
+
+* Add your board to the [board manager](https://github.com/esp8266/Arduino#installing-with-boards-manager). Either ESP8266:
+
+        http://arduino.esp8266.com/stable/package_esp8266com_index.json
+
+  or ESP32:
+
+        https://dl.espressif.com/dl/package_esp32_index.json
+
+* Choose the correct board in *Tools > Board > ...*
+* Choose the correct *Flash size* (e.g. "Flash Size : 4MB (1MB FS, OTA:~1019kB)" for *ESP8266 ESP-12 WIFI*)
+
+* *Verify*
+* *Upload*
+* *Tools > Serial Monitor*
+
+## Authors
+
+ * Eric Duminil
+ * Robert Otto
+ * Myriam Guedey
+ * Tobias Gabriel Erhart
+ * Jonas Stave
+
+Hochschule für Technik Stuttgart
+
+## Contributing
+Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
+
+## License
+
+Copyright © 2020, [HfT Stuttgart](https://www.hft-stuttgart.de/)
+
+[GPLv3](https://choosealicense.com/licenses/gpl-3.0/)

co2_sensor.cpp

+#include "co2_sensor.h"
+
+namespace config {
+  // Values should be defined in config.h
+  uint16_t measurement_timestep = MEASUREMENT_TIMESTEP;  // [s] Value between 2 and 1800 (range for SCD30 sensor)
+  const uint16_t altitude_above_sea_level = ALTITUDE_ABOVE_SEA_LEVEL;  // [m]
+  uint16_t co2_calibration_level = ATMOSPHERIC_CO2_CONCENTRATION;  // [ppm]
+#ifdef TEMPERATURE_OFFSET
+  // Residual heat from CO2 sensor seems to be high enough to change the temperature reading. How much should it be offset?
+  // NOTE: Sign isn't relevant. The returned temperature will always be shifted down.
+  const float temperature_offset = TEMPERATURE_OFFSET;  // [K]
+#else
+  const float temperature_offset = -3.0;  // [K] Temperature measured by sensor is usually at least 3K too high.
+#endif
+  const bool auto_calibrate_sensor = AUTO_CALIBRATE_SENSOR;  // [true / false]
+}
+
+namespace sensor {
+  SCD30 scd30;
+  int16_t co2 = 0;
+  float temperature = 0;
+  float humidity = 0;
+  String timestamp = "";
+
+  void initialize() {
+#if defined(ESP8266)
+    Wire.begin(12, 14);  // ESP8266 - D6, D5;
+#endif
+#if defined(ESP32)
+    Wire.begin(21, 22);  // ESP32
+    /**
+     *  SCD30   ESP32
+     *  VCC --- 3V3
+     *  GND --- GND
+     *  SCL --- SCL (GPIO22) //NOTE: GPIO3 Would be more convenient (right next to GND)
+     *  SDA --- SDA (GPIO21) //NOTE: GPIO1 would be more convenient (right next to GPO3)
+     */
+#endif
+
+    // CO2
+    if (scd30.begin(config::auto_calibrate_sensor) == false) {
+      Serial.println("Air sensor not detected. Please check wiring. Freezing...");
+      while (1) {
+        LedEffects::showWaitingLED(color::red);
+      }
+    }
+
+    // SCD30 has its own timer.
+    Serial.println("\nSetting SCD30 timestep to " + String(config::measurement_timestep) + " s.");
+    scd30.setMeasurementInterval(config::measurement_timestep);  // [s]
+
+    Serial.print("Setting temperature offset to -");
+    Serial.print(abs(config::temperature_offset));
+    Serial.println(" K.");
+    scd30.setTemperatureOffset(abs(config::temperature_offset)); // setTemperatureOffset only accepts positive numbers, but shifts the temperature down.
+
+    Serial.print("Temperature offset is : -");
+    Serial.print(scd30.getTemperatureOffset());
+    Serial.println(" K");
+
+    Serial.print("Auto-calibration is ");
+    Serial.println(config::auto_calibrate_sensor ? "ON." : "OFF.");
+  }
+
+// Force SCD30 calibration with countdown.
+  void startCalibrationProcess() {
+    /** From the sensor documentation:
+     * For best results, the sensor has to be run in a stable environment in continuous mode at
+     * a measurement rate of 2s for at least two minutes before applying the FRC command and sending the reference value.
+     */
+    Serial.println("Setting SCD30 timestep to 2s, prior to calibration.");
+    scd30.setMeasurementInterval(2);  // [s] The change will only take effect after next measurement.
+    LedEffects::showKITTWheel(color::blue, config::measurement_timestep);
+    Serial.println("Waiting 2 minutes.");
+    LedEffects::showKITTWheel(color::blue, 120);
+    Serial.print("Starting SCD30 calibration...");
+    scd30.setAltitudeCompensation(config::altitude_above_sea_level);
+    scd30.setForcedRecalibrationFactor(config::co2_calibration_level);
+    Serial.println(" Done!");
+    Serial.println("Sensor calibrated.");
+    Serial.println("Sensor will now restart.");
+    LedEffects::showKITTWheel(color::green, 5);
+    FS_LIB.end();
+    ESP.restart();
+  }
+}

co2_sensor.h

+#ifndef CO2_SENSOR_H_
+#define CO2_SENSOR_H_
+
+// The SCD30 from Sensirion is a high quality Nondispersive Infrared (NDIR) based CO₂ sensor capable of detecting 400 to 10000ppm with an accuracy of ±(30ppm+3%).
+// https://github.com/sparkfun/SparkFun_SCD30_Arduino_Library
+#include "src/lib/SparkFun_SCD30_Arduino_Library/src/SparkFun_SCD30_Arduino_Library.h"  // From: http://librarymanager/All#SparkFun_SCD30
+#include "config.h"
+#include "led_effects.h"
+#include "csv_writer.h" // To close filesystem before restart.
+#include <Wire.h>
+
+namespace config {
+  extern uint16_t measurement_timestep;  // [s] Value between 2 and 1800 (range for SCD30 sensor)
+  extern const bool auto_calibrate_sensor; // [true / false]
+  extern uint16_t co2_calibration_level;  // [ppm]
+  extern const float temperature_offset; // [K] Sign isn't relevant.
+}
+
+namespace sensor {
+  extern SCD30 scd30;
+  extern int16_t co2;
+  extern float temperature;
+  extern float humidity;
+  extern String timestamp;
+
+  void initialize();
+  void startCalibrationProcess();
+}
+#endif

config.public.h

+#ifndef CONFIG_H_INCLUDED
+#  define CONFIG_H_INCLUDED
+
+// This file is a config template, and can be copied to config.h. Please don't save any important password in this template.
+
+/**
+ * WIFI
+ */
+
+// Setting WIFI_SSID to "NO_WIFI" will disable WiFi completely, and all other dependent services (MQTT, HTTP, NTP, ...)
+#  define WIFI_SSID     "NO_WIFI"
+#  define WIFI_PASSWORD "P4SSW0RD"
+#  define WIFI_TIMEOUT  20 // [s]
+
+/**
+ * Sensor
+ */
+
+// How often should measurement be performed, and displayed?
+//NOTE: SCD30 timer does not seem to be very precise. Variations may occur.
+#  define MEASUREMENT_TIMESTEP 60 // [s] Value between 2 and 1800 (range for SCD30 sensor)
+
+// How often measurements should be sent to MQTT server?
+// Probably a good idea to use a multiple of MEASUREMENT_TIMESTEP, so that averages can be calculated
+// Set to 0 if you want to send values after each measurement
+// #  define SENDING_INTERVAL MEASUREMENT_TIMESTEP * 5 // [s]
+#  define SENDING_INTERVAL 300 // [s]
+
+// How often should measurements be appended to CSV ?
+// Probably a good idea to use a multiple of MEASUREMENT_TIMESTEP, so that averages can be calculated
+// Set to 0 if you want to send values after each measurement
+#  define CSV_INTERVAL 300 // [s]
+
+// Residual heat from CO2 sensor seems to be high enough to change the temperature reading. How much should it be offset?
+// NOTE: Sign isn't relevant. The returned temperature will always be shifted down.
+#  define TEMPERATURE_OFFSET -3 // [K]
+
+// Altitude above sea level
+// Used for CO2 calibration
+// here: Stuttgart, Schellingstr. 24. (Source: Google Earth)
+#  define ALTITUDE_ABOVE_SEA_LEVEL 260 // [m]
+
+// The reference CO2 concentration has to be within the range 400 ppm ≤ cref(CO2) ≤ 2000 ppm.
+// Used for CO2 calibration
+// here : measured concentration in Stuttgart
+#  define ATMOSPHERIC_CO2_CONCENTRATION 425 // [ppm]
+
+// Should the sensor try to calibrate itself?
+// Sensirion recommends 7 days of continuous readings with at least 1 hour a day of 'fresh air' for self-calibration to complete.
+#  define AUTO_CALIBRATE_SENSOR true // [true / false]
+
+/**
+ * LEDs
+ */
+
+// LED brightness, which can vary between min and max brightness ("LED breathing")
+// max_brightness should be between 0 and 255.
+// min_brightness should be between 0 and max_brightness
+#  define MAX_BRIGHTNESS 255
+#  define MIN_BRIGHTNESS 60
+
+/**
+ * WEB SERVER
+ * available at http://local_ip, with user HTTP_USER and password HTTP_PASSWORD
+ */
+
+#  define HTTP // Comment or remove this line if you want to disable HTTP webserver
+
+// Define empty strings in order to disable authentication, or remove the constants altogether.
+#  define HTTP_USER "co2ampel"
+#  define HTTP_PASSWORD "my_password"
+
+/**
+ * MQTT SERVER
+ */
+#  define MQTT // Comment or remove this line if you want to disable MQTT
+
+/*
+ * If MQTT is enabled, co2ampel will publish data every SENDING_INTERVAL seconds.
+ * An MQTT subscriber can then get the data from the corresponding broker, either encrypted or unencrypted:
+ *
+ *  ❯ mosquitto_sub -h 'test.mosquitto.org' -p 8883 -t 'CO2sensors/#' --cafile mosquitto.org.crt -v
+ *  CO2sensors/ESPd05cc9 {"time":"2020-12-13 13:14:37+01", "co2":571, "temp":18.9, "rh":50.9}
+ *  CO2sensors/ESPd05cc9 {"time":"2020-12-13 13:14:48+01", "co2":573, "temp":18.9, "rh":50.2}
+ *  ...
+ *
+ *  ❯ mosquitto_sub -h 'test.mosquitto.org' -t 'CO2sensors/#' -v
+ *  CO2sensors/ESPd05cc9 {"time":"2020-12-13 13:15:09+01", "co2":568, "temp":18.9, "rh":50.1}
+ *  CO2sensors/ESPd05cc9 {"time":"2020-12-13 13:15:20+01", "co2":572, "temp":18.9, "rh":50.3}
+ *  ...
+ */
+
+/*
+ * Allow sensor to be configured over MQTT? Very useful for debugging. For example:
+ *   mosquitto_pub -h 'test.mosquitto.org' -t 'CO2sensors/ESPe08dc9/control' -m 'timer 30'
+ *   mosquitto_pub -h 'test.mosquitto.org' -t 'CO2sensors/ESPe08dc9/control' -m 'calibrate'
+ *   mosquitto_pub -h 'test.mosquitto.org' -t 'CO2sensors/ESPe08dc9/control' -m 'reset'
+ */
+#  define ALLOW_MQTT_COMMANDS false
+
+#  define MQTT_SERVER "test.mosquitto.org"  // MQTT server URL or IP address
+#  define MQTT_PORT 8883
+#  define MQTT_USER ""
+#  define MQTT_PASSWORD ""
+#  define MQTT_SERVER_FINGERPRINT "EE BC 4B F8 57 E3 D3 E4 07 54 23 1E F0 C8 A1 56 E0 D3 1A 1C" // SHA1 for test.mosquitto.org
+
+/**
+ * NTP
+ */
+
+#  define NTP_SERVER "pool.ntp.org"
+#  define UTC_OFFSET_IN_SECONDS 3600 // [s] 3600 for UTC+1
+
+/**
+ * Others
+ */
+#  define BAUDS 115200 // Transmission rate
+
+#endif

csv_writer.cpp

+#include "csv_writer.h"
+
+namespace config {
+  // Values should be defined in config.h
+  uint16_t csv_interval = CSV_INTERVAL; // [s]
+}
+namespace csv_writer {
+  unsigned long last_written_at = 0;
+  String last_successful_write = "";
+
+#if defined(ESP8266)
+  /**
+   * SPECIFIC FUNCTIONS FOR LITTLEFS
+   */
+  FSInfo fs_info;
+
+  bool mountFS() {
+    return LittleFS.begin(); // format if needed.
+  }
+
+  void updateFsInfo() {
+    FS_LIB.info(fs_info);
+  }
+
+  int getTotalSpace() {
+    return fs_info.totalBytes;
+  }
+
+  int getUsedSpace() {
+    return fs_info.usedBytes;
+  }
+
+  void showFilesystemContent() {
+    Dir dir = FS_LIB.openDir("/");