Add SenseAir S8 CO2 sensor support

code/espurna/config/sensors.h

@@ -373,6 +373,23 @@
 #define MHZ19_TX_PIN                    15
 #endif
 
+//------------------------------------------------------------------------------
+// SenseAir CO2 sensor
+// Enable support by passing SENSEAIR_SUPPORT=1 build flag
+//------------------------------------------------------------------------------
+
+#ifndef SENSEAIR_SUPPORT
+#define SENSEAIR_SUPPORT                0
+#endif
+
+#ifndef SENSEAIR_RX_PIN
+#define SENSEAIR_RX_PIN                 0
+#endif
+
+#ifndef SENSEAIR_TX_PIN
+#define SENSEAIR_TX_PIN                 2
+#endif
+
 //------------------------------------------------------------------------------
 // Particle Monitor based on Plantower PMSX003
 // Enable support by passing PMSX003_SUPPORT=1 build flag
@@ -503,6 +520,7 @@
     HCSR04_SUPPORT || \
     HLW8012_SUPPORT || \
     MHZ19_SUPPORT || \
+	SENSEAIR_SUPPORT || \
     PMSX003_SUPPORT || \
     PZEM004T_SUPPORT || \
     SHT3X_I2C_SUPPORT || \
@@ -624,6 +642,11 @@
     #include "../sensors/MHZ19Sensor.h"
 #endif
 
+#if SENSEAIR_SUPPORT
+    #include <SoftwareSerial.h>
+    #include "../sensors/SenseAirSensor.h"
+#endif
+
 #if PMSX003_SUPPORT
     #include <SoftwareSerial.h>
     #include <PMS.h>

code/espurna/config/types.h

@@ -249,6 +249,7 @@
 #define SENSOR_CSE7766_ID           0x21
 #define SENSOR_TMP3X_ID             0x22
 #define SENSOR_HCSR04_ID            0x23
+#define SENSOR_SENSEAIR_ID          0x24
 
 //--------------------------------------------------------------------------------
 // Magnitudes

code/espurna/sensor.ino

@@ -487,6 +487,15 @@ void _sensorLoad() {
     }
     #endif
 
+    #if SENSEAIR_SUPPORT
+    {
+        SenseAirSensor * sensor = new SenseAirSensor();
+        sensor->setRX(SENSEAIR_RX_PIN);
+        sensor->setTX(SENSEAIR_TX_PIN);
+        _sensors.push_back(sensor);
+    }
+    #endif
+
     #if PMSX003_SUPPORT
     {
         PMSX003Sensor * sensor = new PMSX003Sensor();

code/espurna/sensors/SenseAirSensor.h

@@ -0,0 +1,233 @@
+// -----------------------------------------------------------------------------
+// SenseAir S8 CO2 Sensor
+// Uses SoftwareSerial library
+// Contribution by Yonsm Guo
+// -----------------------------------------------------------------------------
+
+#if SENSOR_SUPPORT && SENSEAIR_SUPPORT
+
+#pragma once
+
+#include "Arduino.h"
+#include "BaseSensor.h"
+
+#include <SoftwareSerial.h>
+
+// SenseAir sensor utils
+class SenseAir
+{
+protected:
+    SoftwareSerial *_serial; // Should initialized by child class
+
+public:
+    int sendCommand(byte command[]) {
+        byte recv_buf[7] = {0xff};
+        byte data_buf[2] = {0xff};
+        long value       = -1;
+
+        _serial->write(command, 8); //Send the byte array
+        delay(50);
+
+        // Read answer from sensor
+        int ByteCounter = 0;
+        while(_serial->available()) {
+            recv_buf[ByteCounter] = _serial->read();
+            ByteCounter++;
+        }
+
+        data_buf[0] = recv_buf[3];
+        data_buf[1] = recv_buf[4];
+        value = (data_buf[0] << 8) | (data_buf[1]);
+
+        return value;
+    }
+
+    int readCo2(void) {
+        int co2 = 0;
+        byte frame[8] = {0};
+        buildFrame(0xFE, 0x04, 0x03, 1, frame);
+        co2 = sendCommand(frame);
+        return co2;
+    }
+
+private:
+    // Compute the MODBUS RTU CRC
+    static unsigned int modRTU_CRC(byte buf[], int len, byte checkSum[2]) {
+        unsigned int crc = 0xFFFF;
+
+        for (int pos = 0; pos < len; pos++) {
+            crc ^= (unsigned int)buf[pos];          // XOR byte into least sig. byte of crc
+
+            for (int i = 8; i != 0; i--) {    // Loop over each bit
+            if ((crc & 0x0001) != 0) {      // If the LSB is set
+                crc >>= 1;                    // Shift right and XOR 0xA001
+                crc ^= 0xA001;
+            }
+            else                            // Else LSB is not set
+                crc >>= 1;                    // Just shift right
+            }
+        }
+        // Note, this number has low and high bytes swapped, so use it accordingly (or swap bytes)
+        checkSum[1] = (byte)((crc >> 8) & 0xFF);
+        checkSum[0] = (byte)(crc & 0xFF);
+        return crc;
+    }
+
+    static int getBitOfInt(int reg, int pos) {
+        // Create a mask
+        int mask = 0x01 << pos;
+
+        // Mask the status register
+        int masked_register = mask & reg;
+
+        // Shift the result of masked register back to position 0
+        int result = masked_register >> pos;
+
+        return result;
+    }
+
+
+    static void buildFrame(byte slaveAddress,
+                byte  functionCode,
+                short startAddress,
+                short numberOfRegisters,
+                byte frame[8]) {
+        frame[0] = slaveAddress;
+        frame[1] = functionCode;
+        frame[2] = (byte)(startAddress >> 8);
+        frame[3] = (byte)(startAddress);
+        frame[4] = (byte)(numberOfRegisters >> 8);
+        frame[5] = (byte)(numberOfRegisters);
+        // CRC-calculation
+        byte checkSum[2] = {0};
+        modRTU_CRC(frame, 6, checkSum);
+        frame[6] = checkSum[0];
+        frame[7] = checkSum[1];
+    }
+};
+
+//
+class SenseAirSensor : public BaseSensor, SenseAir {
+
+    public:
+
+        // ---------------------------------------------------------------------
+        // Public
+        // ---------------------------------------------------------------------
+
+        SenseAirSensor(): BaseSensor() {
+            _count = 1;
+            _co2 = 0;
+            _lastCo2 = 0;
+            _serial = NULL;
+            _sensor_id = SENSOR_SENSEAIR_ID;
+        }
+
+        ~SenseAirSensor() {
+            if (_serial) delete _serial;
+            _serial = NULL;
+        }
+
+        void setRX(unsigned char pin_rx) {
+            if (_pin_rx == pin_rx) return;
+            _pin_rx = pin_rx;
+            _dirty = true;
+        }
+
+        void setTX(unsigned char pin_tx) {
+            if (_pin_tx == pin_tx) return;
+            _pin_tx = pin_tx;
+            _dirty = true;
+        }
+
+        // ---------------------------------------------------------------------
+
+        unsigned char getRX() {
+            return _pin_rx;
+        }
+
+        unsigned char getTX() {
+            return _pin_tx;
+        }
+
+        // ---------------------------------------------------------------------
+        // Sensor API
+        // ---------------------------------------------------------------------
+
+        // Initialization method, must be idempotent
+        void begin() {
+
+            if (!_dirty) return;
+
+            if (_serial) delete _serial;
+
+            _serial = new SoftwareSerial(_pin_rx, _pin_tx, false, 64);
+            _serial->enableIntTx(false);
+            _serial->begin(9600);
+            _serial->enableRx(true);
+
+            _startTime = 0;
+            _ready = true;
+            _dirty = false;
+        }
+
+        // Descriptive name of the sensor
+        String description() {
+            char buffer[28];
+            snprintf(buffer, sizeof(buffer), "SenseAir S8 @ SwSerial(%u,%u)", _pin_rx, _pin_tx);
+            return String(buffer);
+        }
+
+        // Descriptive name of the slot # index
+        String slot(unsigned char index) {
+            return description();
+        }
+
+        // Address of the sensor (it could be the GPIO or I2C address)
+        String address(unsigned char index) {
+            char buffer[6];
+            snprintf(buffer, sizeof(buffer), "%u:%u", _pin_rx, _pin_tx);
+            return String(buffer);
+        }
+
+        // Type for slot # index
+        unsigned char type(unsigned char index) {
+            return MAGNITUDE_CO2;
+        }
+
+        void pre() {
+
+            if (millis() - _startTime < 20000) {
+                _error = SENSOR_ERROR_WARM_UP;
+                return;
+            }
+
+            _error = SENSOR_ERROR_OK;
+
+            unsigned int co2 = readCo2();
+            if (co2 >= 5000 || co2 < 100)
+            {
+                _co2 = _lastCo2;
+            }
+            else
+            {
+                _co2 = (co2 > _lastCo2 + 2000) ? _lastCo2 : co2;
+                _lastCo2 = co2;
+            }
+        }
+
+        // Current value for slot # index
+        double value(unsigned char index) {
+            return _co2;
+        }
+
+    protected:
+        unsigned int _pin_rx;
+        unsigned int _pin_tx;
+        unsigned long _startTime;
+        unsigned int _co2;
+        unsigned int _lastCo2;
+};
+
+
+#endif // SENSOR_SUPPORT && SENSEAIR_SUPPORT