Commit aa5e2240 authored by Eric Duminil's avatar Eric Duminil
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# CO<sub>2</sub> Ampel
*CO<sub>2</sub> Ampel* is an open-source project, written in C++ for ESP8266 or ESP32.
*CO<sub>2</sub> Ampel* is an open-source project, written in C++ for [ESP8266](https://en.wikipedia.org/wiki/ESP8266) or [ESP32](https://en.wikipedia.org/wiki/ESP32).
It measures the current CO<sub>2</sub> concentration (in ppm), and displays it on an LED ring.
......@@ -12,11 +12,11 @@ The *CO<sub>2</sub> Ampel* can:
* Display CO2 concentration on LED ring.
* Allow calibration.
* Get current time over NTP
* Send data over MQTT.
* Send data over LoRaWAN.
* Get current time over [NTP](https://en.wikipedia.org/wiki/Network_Time_Protocol)
* Send data over [MQTT](https://en.wikipedia.org/wiki/MQTT).
* Send data over [LoRaWAN](https://en.wikipedia.org/wiki/LoRa#LoRaWAN).
* Display measurements and configuration on a small website.
* Log data to a CSV file, directly on the ESP flash memory.
* Log data to a [CSV](https://en.wikipedia.org/wiki/Comma-separated_values) file, directly on the ESP flash memory.
## Hardware Requirements
......@@ -85,5 +85,4 @@ make upload board=esp32 && make monitor # For ESP32
## License
Copyright © 2021, [HfT Stuttgart](https://www.hft-stuttgart.de/)
[GPLv3](https://choosealicense.com/licenses/gpl-3.0/)
......@@ -15,6 +15,7 @@ namespace config {
const float temperature_offset = -3.0; // [K] Temperature measured by sensor is usually at least 3K too high.
#endif
bool auto_calibrate_sensor = AUTO_CALIBRATE_SENSOR; // [true / false]
const bool debug_sensor_states = false; // If true, log state transitions over serial console
}
namespace sensor {
......@@ -24,12 +25,39 @@ namespace sensor {
float humidity = 0;
char timestamp[23];
int16_t stable_measurements = 0;
uint32_t waiting_color = color::blue;
bool should_calibrate = false;
/**
* Define sensor states
* INITIAL -> initial state
* BOOTUP -> state after initializing the sensor, i.e. after scd.begin()
* READY -> sensor does output valid information (> 0 ppm) and no other condition takes place
* NEEDS_CALIBRATION -> sensor measurements are too low (< 250 ppm)
* PREPARE_CALIBRATION -> forced calibration was initiated, waiting for stable measurements
* CALIBRATION -> the sensor does calibrate itself
*/
enum state {
INITIAL,
BOOTUP,
READY,
NEEDS_CALIBRATION,
PREPARE_CALIBRATION_UNSTABLE,
PREPARE_CALIBRATION_STABLE,
CALIBRATION
};
const char *state_names[] = {
"INITIAL",
"BOOTUP",
"READY",
"NEEDS_CALIBRATION",
"PREPARE_CALIBRATION_UNSTABLE",
"PREPARE_CALIBRATION_STABLE",
"CALIBRATION" };
state current_state = INITIAL;
void switchState(state);
void initialize() {
#if defined(ESP8266)
Wire.begin(12, 14); // ESP8266 - D6, D5;
Wire.begin(12, 14); // ESP8266 - D6, D5;
#endif
#if defined(ESP32)
Wire.begin(21, 22); // ESP32
......@@ -41,17 +69,19 @@ namespace sensor {
* SDA --- SDA (GPIO21) //NOTE: GPIO1 would be more convenient (right next to GPO3)
*/
#endif
Serial.println();
scd30.enableDebugging(); // Prints firmware version in the console.
// CO2
if (scd30.begin(config::auto_calibrate_sensor) == false) {
if (!scd30.begin(config::auto_calibrate_sensor)) {
Serial.println(F("ERROR - CO2 sensor not detected. Please check wiring!"));
led_effects::showKITTWheel(color::red, 30);
ESP.restart();
}
switchState(BOOTUP);
// SCD30 has its own timer.
//NOTE: The timer seems to be inaccurate, though, possibly depending on voltage. Should it be offset?
Serial.println();
Serial.print(F("Setting SCD30 timestep to "));
Serial.print(config::measurement_timestep);
Serial.println(" s.");
......@@ -91,19 +121,21 @@ namespace sensor {
previous_measurement_at = now;
}
void countStableMeasurements() {
bool countStableMeasurements() {
// Returns true, if a sufficient number of stable measurements has been observed.
static int16_t previous_co2 = 0;
if (co2 > (previous_co2 - config::max_deviation_during_calibration)
&& co2 < (previous_co2 + config::max_deviation_during_calibration)) {
stable_measurements++;
Serial.print(F("Number of stable measurements : "));
Serial.println(stable_measurements);
waiting_color = color::green;
switchState(PREPARE_CALIBRATION_STABLE);
} else {
stable_measurements = 0;
waiting_color = color::red;
switchState(PREPARE_CALIBRATION_UNSTABLE);
}
previous_co2 = co2;
return (stable_measurements == config::enough_stable_measurements);
}
void startCalibrationProcess() {
......@@ -115,10 +147,11 @@ namespace sensor {
scd30.setMeasurementInterval(2); // [s] The change will only take effect after next measurement.
Serial.println(F("Waiting until the measurements are stable for at least 2 minutes."));
Serial.println(F("It could take a very long time."));
should_calibrate = true;
switchState(PREPARE_CALIBRATION_UNSTABLE);
}
void calibrateAndRestart() {
switchState(CALIBRATION);
Serial.print(F("Calibrating SCD30 now..."));
scd30.setAltitudeCompensation(config::altitude_above_sea_level);
scd30.setForcedRecalibrationFactor(config::co2_calibration_level);
......@@ -137,12 +170,41 @@ namespace sensor {
Serial.println(humidity, 1);
}
void displayCO2OnLedRing() {
if (co2 < 250) {
// Sensor should be calibrated.
led_effects::showWaitingLED(color::magenta);
void switchState(state new_state) {
if (new_state == current_state) {
return;
}
if (config::debug_sensor_states) {
Serial.print(F("Changing sensor state: "));
Serial.print(state_names[current_state]);
Serial.print(" -> ");
Serial.println(state_names[new_state]);
}
current_state = new_state;
}
void switchStateForCurrentPPM() {
if (co2 == 0) {
// NOTE: Data is available, but it's sometimes erroneous: the sensor outputs
// zero ppm but non-zero temperature and non-zero humidity.
Serial.println(F("Invalid sensor data - CO2 concentration supposedly 0 ppm"));
switchState(BOOTUP);
} else if ((current_state == PREPARE_CALIBRATION_UNSTABLE) || (current_state == PREPARE_CALIBRATION_STABLE)) {
// Check for pre-calibration states first, because we do not want to
// leave them before calibration is done.
bool ready_for_calibration = countStableMeasurements();
if (ready_for_calibration) {
calibrateAndRestart();
}
} else if (co2 < 250) {
// Sensor should be calibrated.
switchState(NEEDS_CALIBRATION);
} else {
switchState(READY);
}
}
void displayCO2OnLedRing() {
/**
* Display data, even if it's "old" (with breathing).
* A short delay is required in order to let background tasks run on the ESP8266.
......@@ -157,6 +219,30 @@ namespace sensor {
}
}
void showState() {
switch (current_state) {
case BOOTUP:
led_effects::showWaitingLED(color::blue);
break;
case READY:
displayCO2OnLedRing();
break;
case NEEDS_CALIBRATION:
led_effects::showWaitingLED(color::magenta);
break;
case PREPARE_CALIBRATION_UNSTABLE:
led_effects::showWaitingLED(color::red);
break;
case PREPARE_CALIBRATION_STABLE:
led_effects::showWaitingLED(color::green);
break;
case CALIBRATION: // Nothing to do, will restart soon.
break;
default:
Serial.println(F("Encountered unknown sensor state")); // This should not happen.
}
}
/** Gets fresh data if available, checks calibration status, displays CO2 levels.
* Returns true if fresh data is available, for further processing (e.g. MQTT, CSV or LoRa)
*/
......@@ -169,34 +255,15 @@ namespace sensor {
co2 = scd30.getCO2();
temperature = scd30.getTemperature();
humidity = 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 (co2 <= 0) {
// No measurement yet. Waiting.
led_effects::showWaitingLED(color::blue);
return false;
}
switchStateForCurrentPPM();
/**
* Fresh data. Log it and send it if needed.
*/
if (freshData) {
if (should_calibrate) {
countStableMeasurements();
}
// Log every time fresh data is available.
logToSerial();
}
if (should_calibrate) {
if (stable_measurements == config::enough_stable_measurements) {
calibrateAndRestart();
}
led_effects::showWaitingLED(waiting_color);
return false;
}
showState();
displayCO2OnLedRing();
return freshData;
}
......@@ -207,6 +274,7 @@ namespace sensor {
Serial.print(F("DEBUG. Setting CO2 to "));
co2 = fakeCo2;
Serial.println(co2);
switchStateForCurrentPPM();
}
void setAutoCalibration(int32_t autoCalibration) {
......
......@@ -87,6 +87,7 @@ namespace csv_writer {
void initialize(const char *sensorId) {
snprintf(filename, sizeof(filename), "/%s.csv", sensorId);
Serial.println();
Serial.print(F("Initializing FS..."));
if (mountFS()) {
Serial.println(F("done."));
......
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