Added support for MHZ19 CO2 sensor

code/espurna/config/general.h

@@ -755,51 +755,6 @@ PROGMEM const char* const custom_reset_string[] = {
 #define RF_SEND_DELAY           250             // Interval between sendings in ms
 #define RF_RECEIVE_DELAY        500             // Interval between recieving in ms (avoid debouncing)
 
-// -----------------------------------------------------------------------------
-// SENSORS
-// -----------------------------------------------------------------------------
-
-#define SENSOR_READ_INTERVAL            6000            // Read data from sensors every 6 seconds
-#define SENSOR_REPORT_EVERY             10              // Report every this many readings
-#define SENSOR_USE_INDEX                0               // Use the index in topic (i.e. temperature/0)
-                                                        // even if just one sensor (0 for backwards compatibility)
-
-#define SENSOR_TEMPERATURE_DECIMALS     1
-#define SENSOR_HUMIDITY_DECIMALS        0
-#define SENSOR_PRESSURE_DECIMALS        2
-#define SENSOR_ANALOG_DECIMALS          0
-#define SENSOR_EVENTS_DECIMALS          0
-#define SENSOR_CURRENT_DECIMALS         3
-#define SENSOR_VOLTAGE_DECIMALS         0
-#define SENSOR_POWER_DECIMALS           0
-#define SENSOR_POWER_FACTOR_DECIMALS    0
-#define SENSOR_ENERGY_DECIMALS          0
-#define SENSOR_PM1dot0_DECIMALS         0
-#define SENSOR_PM2dot5_DECIMALS         0
-#define SENSOR_PM10_DECIMALS            0
-
-#define SENSOR_UNKNOWN_TOPIC            "unknown"
-#define SENSOR_TEMPERATURE_TOPIC        "temperature"
-#define SENSOR_HUMIDITY_TOPIC           "humidity"
-#define SENSOR_PRESSURE_TOPIC           "pressure"
-#define SENSOR_CURRENT_TOPIC            "current"
-#define SENSOR_VOLTAGE_TOPIC            "voltage"
-#define SENSOR_ACTIVE_POWER_TOPIC       "power"
-#define SENSOR_APPARENT_POWER_TOPIC     "apparent"
-#define SENSOR_REACTIVE_POWER_TOPIC     "reactive"
-#define SENSOR_POWER_FACTOR_TOPIC       "factor"
-#define SENSOR_ENERGY_TOPIC             "energy"
-#define SENSOR_ENERGY_DELTA_TOPIC       "energy_delta"
-#define SENSOR_PM1dot0_TOPIC            "pm1dot0"
-#define SENSOR_PM2dot5_TOPIC            "pm2dot5"
-#define SENSOR_PM10_TOPIC               "pm10"
-#define SENSOR_ANALOG_TOPIC             "analog"
-#define SENSOR_DIGITAL_TOPIC            "digital"
-#define SENSOR_EVENTS_TOPIC             "events"
-
-#define SENSOR_TEMPERATURE_UNITS        TMP_CELSIUS     // Temperature units (TMP_CELSIUS | TMP_FAHRENHEIT)
-#define SENSOR_TEMPERATURE_CORRECTION   0.0             // Offset correction
-
 // -----------------------------------------------------------------------------
 // IR
 // -----------------------------------------------------------------------------

code/espurna/config/prototypes.h

@@ -82,6 +82,9 @@ template<typename T> bool idbSend(const char * topic, unsigned char id, T payloa
 #include <SoftwareSerial.h>
 #include <PMS.h>
 #endif
+#if MHZ19_SUPPORT
+#include <SoftwareSerial.h>
+#endif
 #if BME280_SUPPORT
 #include <SparkFunBME280.h>
 #endif

code/espurna/config/sensors.h

@@ -1,16 +1,51 @@
-//--------------------------------------------------------------------------------
-// General
-//--------------------------------------------------------------------------------
-
-#ifndef TEMPERATURE_MIN_CHANGE
-#define TEMPERATURE_MIN_CHANGE      0.0             // Minimum temperature change to report
-#endif
-
-#ifndef HUMIDITY_MIN_CHANGE
-#define HUMIDITY_MIN_CHANGE         0               // Minimum humidity change to report
-#endif
-
-#define TEMPERATURE_DECIMALS        1               // Decimals for temperature values
+// -----------------------------------------------------------------------------
+// SENSORS
+// -----------------------------------------------------------------------------
+
+#define SENSOR_READ_INTERVAL            6000            // Read data from sensors every 6 seconds
+#define SENSOR_REPORT_EVERY             10              // Report every this many readings
+#define SENSOR_USE_INDEX                0               // Use the index in topic (i.e. temperature/0)
+                                                        // even if just one sensor (0 for backwards compatibility)
+
+#define SENSOR_TEMPERATURE_UNITS        TMP_CELSIUS     // Temperature units (TMP_CELSIUS | TMP_FAHRENHEIT)
+#define SENSOR_TEMPERATURE_CORRECTION   0.0             // Offset correction
+#define TEMPERATURE_MIN_CHANGE          0.0             // Minimum temperature change to report
+#define HUMIDITY_MIN_CHANGE             0               // Minimum humidity change to report
+
+#define SENSOR_TEMPERATURE_DECIMALS     1
+#define SENSOR_HUMIDITY_DECIMALS        0
+#define SENSOR_PRESSURE_DECIMALS        2
+#define SENSOR_ANALOG_DECIMALS          0
+#define SENSOR_EVENTS_DECIMALS          0
+#define SENSOR_CURRENT_DECIMALS         3
+#define SENSOR_VOLTAGE_DECIMALS         0
+#define SENSOR_POWER_DECIMALS           0
+#define SENSOR_POWER_FACTOR_DECIMALS    0
+#define SENSOR_ENERGY_DECIMALS          0
+#define SENSOR_PM1dot0_DECIMALS         0
+#define SENSOR_PM2dot5_DECIMALS         0
+#define SENSOR_PM10_DECIMALS            0
+#define SENSOR_CO2_DECIMALS             0
+
+#define SENSOR_UNKNOWN_TOPIC            "unknown"
+#define SENSOR_TEMPERATURE_TOPIC        "temperature"
+#define SENSOR_HUMIDITY_TOPIC           "humidity"
+#define SENSOR_PRESSURE_TOPIC           "pressure"
+#define SENSOR_CURRENT_TOPIC            "current"
+#define SENSOR_VOLTAGE_TOPIC            "voltage"
+#define SENSOR_ACTIVE_POWER_TOPIC       "power"
+#define SENSOR_APPARENT_POWER_TOPIC     "apparent"
+#define SENSOR_REACTIVE_POWER_TOPIC     "reactive"
+#define SENSOR_POWER_FACTOR_TOPIC       "factor"
+#define SENSOR_ENERGY_TOPIC             "energy"
+#define SENSOR_ENERGY_DELTA_TOPIC       "energy_delta"
+#define SENSOR_PM1dot0_TOPIC            "pm1dot0"
+#define SENSOR_PM2dot5_TOPIC            "pm2dot5"
+#define SENSOR_PM10_TOPIC               "pm10"
+#define SENSOR_ANALOG_TOPIC             "analog"
+#define SENSOR_DIGITAL_TOPIC            "digital"
+#define SENSOR_EVENTS_TOPIC             "events"
+#define SENSOR_CO2_TOPIC                "co2"
 
 //--------------------------------------------------------------------------------
 // DHTXX temperature/humidity sensor
@@ -244,6 +279,18 @@
 #define PMS_RX_PIN                      13
 #define PMS_TX_PIN                      15
 
+//--------------------------------------------------------------------------------
+// MHZ19 CO2 sensor
+// Enable support by passing MHZ19_SUPPORT=1 build flag
+//--------------------------------------------------------------------------------
+
+#ifndef MHZ19_SUPPORT
+#define MHZ19_SUPPORT                   1
+#endif
+
+#define MHZ19_RX_PIN                    13
+#define MHZ19_TX_PIN                    15
+
 //--------------------------------------------------------------------------------
 // Internal power montior
 // Enable support by passing ADC_VCC_ENABLED=1 build flag

code/espurna/sensor.ino

@@ -55,6 +55,7 @@ String _sensorTopic(magnitude_t type) {
     if (type == MAGNITUDE_PM1dot0) return String(SENSOR_PM1dot0_TOPIC);
     if (type == MAGNITUDE_PM2dot5) return String(SENSOR_PM2dot5_TOPIC);
     if (type == MAGNITUDE_PM10) return String(SENSOR_PM10_TOPIC);
+    if (type == MAGNITUDE_CO2) return String(SENSOR_CO2_TOPIC);
     return String(SENSOR_UNKNOWN_TOPIC);
 }
 
@@ -75,6 +76,7 @@ unsigned char _sensorDecimals(magnitude_t type) {
     if (type == MAGNITUDE_PM1dot0) return SENSOR_PM1dot0_DECIMALS;
     if (type == MAGNITUDE_PM2dot5) return SENSOR_PM2dot5_DECIMALS;
     if (type == MAGNITUDE_PM10) return SENSOR_PM10_DECIMALS;
+    if (type == MAGNITUDE_CO2) return SENSOR_CO2_DECIMALS;
     return 0;
 }
 
@@ -94,6 +96,7 @@ String _sensorUnits(magnitude_t type) {
     if (type == MAGNITUDE_PM1dot0) return String("µg/m3");
     if (type == MAGNITUDE_PM2dot5) return String("µg/m3");
     if (type == MAGNITUDE_PM10) return String("µg/m3");
+    if (type == MAGNITUDE_CO2) return String("ppm");
     return String();
 }
 
@@ -282,6 +285,11 @@ void sensorInit() {
         sensorRegister(new PMSX003Sensor(PMS_RX_PIN, PMS_TX_PIN));
     #endif
 
+    #if MHZ19_SUPPORT
+        #include "sensors/MHZ19Sensor.h"
+        sensorRegister(new MHZ19Sensor(MHZ19_RX_PIN, MHZ19_TX_PIN));
+    #endif
+
     #if COUNTER_SUPPORT
         #include "sensors/EventSensor.h"
         sensorRegister(new EventSensor(COUNTER_PIN, COUNTER_PIN_MODE, COUNTER_DEBOUNCE));

code/espurna/sensors/BaseSensor.h

@@ -31,13 +31,16 @@ typedef enum magnitude_t {
     MAGNITUDE_PM2dot5,
     MAGNITUDE_PM10,
 
+    MAGNITUDE_CO2,
+
     MAGNITUDE_MAX,
 
 } magnitude_t;
 
-#define SENSOR_ERROR_OK             0
-#define SENSOR_ERROR_OUT_OF_RANGE   1
-#define SENSOR_ERROR_WARM_UP        2
+#define SENSOR_ERROR_OK             0       // No error
+#define SENSOR_ERROR_OUT_OF_RANGE   1       // Result out of sensor range
+#define SENSOR_ERROR_WARM_UP        2       // Sensor is warming-up
+#define SENSOR_ERROR_TIMEOUT        3       // Response from sensor timed out
 
 class BaseSensor {
 

code/espurna/sensors/MHZ19Sensor.h

@@ -0,0 +1,162 @@
+// -----------------------------------------------------------------------------
+// MHZ19 CO2 sensor
+// Based on: https://github.com/nara256/mhz19_uart
+// http://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh-z19b-co2-ver1_0.pdf
+// -----------------------------------------------------------------------------
+
+#pragma once
+
+#include "Arduino.h"
+#include "BaseSensor.h"
+#include <SoftwareSerial.h>
+
+#define MHZ19_REQUEST_LEN       8
+#define MHZ19_RESPONSE_LEN      9
+#define MHZ19_TIMEOUT           1000
+#define MHZ19_GETPPM            0x8600
+#define MHZ19_ZEROCALIB         0x8700
+#define MHZ19_SPANCALIB         0x8800
+#define MHZ19_AUTOCALIB_ON      0x79A0
+#define MHZ19_AUTOCALIB_OFF     0x7900
+
+class MHZ19Sensor : public BaseSensor {
+
+    public:
+
+        MHZ19Sensor(int pin_rx = MHZ19_RX_PIN, int pin_tx = MHZ19_TX_PIN): BaseSensor() {
+
+            // Cache
+            _pin_rx = pin_rx;
+            _pin_tx = pin_tx;
+            _count = 1;
+
+            // Init
+            _serial = new SoftwareSerial(pin_rx, pin_tx, false, 256);
+            _serial->begin(9600);
+            calibrateAuto(false);
+
+        }
+
+        // Descriptive name of the sensor
+        String name() {
+            char buffer[28];
+            snprintf(buffer, sizeof(buffer), "MHZ19 @ SwSerial(%i,%i)", _pin_rx, _pin_tx);
+            return String(buffer);
+        }
+
+        // Descriptive name of the slot # index
+        String slot(unsigned char index) {
+            return name();
+        }
+
+        // Type for slot # index
+        magnitude_t type(unsigned char index) {
+            _error = SENSOR_ERROR_OK;
+            if (index == 0) return MAGNITUDE_CO2;
+            _error = SENSOR_ERROR_OUT_OF_RANGE;
+            return MAGNITUDE_NONE;
+        }
+
+        void pre() {
+            _read();
+        }
+
+        // Current value for slot # index
+        double value(unsigned char index) {
+            _error = SENSOR_ERROR_OK;
+            if (index == 0) return _co2;
+            _error = SENSOR_ERROR_OUT_OF_RANGE;
+            return 0;
+        }
+
+        void calibrateAuto(boolean state){
+        	_write(state ? MHZ19_AUTOCALIB_ON : MHZ19_AUTOCALIB_OFF);
+        }
+
+        void calibrateZero() {
+        	_write(MHZ19_ZEROCALIB);
+        }
+
+        void calibrateSpan(unsigned int ppm) {
+            if( ppm < 1000 ) return;
+            unsigned char buffer[MHZ19_REQUEST_LEN] = {0};
+            buffer[0] = 0xFF;
+            buffer[1] = 0x01;
+            buffer[2] = MHZ19_SPANCALIB >> 8;
+            buffer[3] = ppm >> 8;
+            buffer[4] = ppm & 0xFF;
+            _write(buffer);
+        }
+
+    protected:
+
+        void _write(unsigned char * command) {
+            _serial->write(command, MHZ19_REQUEST_LEN);
+        	_serial->write(_checksum(command));
+        	_serial->flush();
+        }
+
+        void _write(unsigned int command, unsigned char * response) {
+
+            unsigned char buffer[MHZ19_REQUEST_LEN] = {0};
+            buffer[0] = 0xFF;
+            buffer[1] = 0x01;
+            buffer[2] = command >> 8;
+            buffer[3] = command & 0xFF;
+            _write(buffer);
+
+        	if (response != NULL) {
+        		unsigned long start = millis();
+                while (_serial->available() == 0) {
+                    if (millis() - start > MHZ19_TIMEOUT) {
+                        _error = SENSOR_ERROR_TIMEOUT;
+                        return;
+                    }
+                    yield();
+                }
+        		_serial->readBytes(response, MHZ19_RESPONSE_LEN);
+        	}
+
+        }
+
+        void _write(unsigned int command) {
+            _write(command, NULL);
+        }
+
+        void _read() {
+
+            unsigned char buffer[MHZ19_RESPONSE_LEN] = {0};
+        	_write(MHZ19_GETPPM, buffer);
+
+        	// Check response
+        	if ((buffer[0] == 0xFF)
+                && (buffer[1] == 0x86)
+                && (_checksum(buffer) == buffer[MHZ19_RESPONSE_LEN-1])) {
+
+                unsigned int value = buffer[2] * 256 + buffer[3];
+                if (0 <= value && value <= 5000) {
+                    _co2 = value;
+                    _error = SENSOR_ERROR_OK;
+                } else {
+                    _error = SENSOR_ERROR_OUT_OF_RANGE;
+                }
+
+            }
+
+        }
+
+        uint8_t _checksum(uint8_t * command) {
+        	uint8_t sum = 0x00;
+        	for (unsigned char i = 1; i < MHZ19_REQUEST_LEN-1; i++) {
+        		sum += command[i];
+        	}
+        	sum = 0xFF - sum + 0x01;
+        	return sum;
+        }
+
+        double _co2 = 0;
+        unsigned int _pin_rx;
+        unsigned int _pin_tx;
+        SoftwareSerial * _serial;
+
+};

code/html/custom.js

@@ -33,7 +33,7 @@ function sensorType(type) {
         "Current", "Voltage", "Active Power", "Apparent Power",
         "Reactive Power", "Energy", "Energy (delta)", "Power Factor",
         "Analog", "Digital", "Events",
-        "PM1.0", "PM2.5", "PM10"
+        "PM1.0", "PM2.5", "PM10", "CO2"
     ];
     if (1 <= type && type <= types.length) return types[type-1];
     return null;