Added support for Wemos SHT3X I2C sensor shield

code/espurna/config/sensors.h

@@ -89,6 +89,7 @@
 #define SENSOR_BMX280_ID                0x13
 #define SENSOR_MHZ19_ID                 0x14
 #define SENSOR_SI7021_ID                0x15
+#define SENSOR_SHT3X_I2C_ID             0x16
 
 // =============================================================================
 // Specific data for each sensor
@@ -294,6 +295,24 @@
 #define PMS_RX_PIN                      13
 #define PMS_TX_PIN                      15
 
+//------------------------------------------------------------------------------
+// SHT3X I2C (Wemos) temperature & humidity sensor
+// Enable support by passing SHT3X_SUPPORT=1 build flag
+//------------------------------------------------------------------------------
+
+#ifndef SHT3X_I2C_SUPPORT
+#define SHT3X_I2C_SUPPORT               0
+#endif
+
+#ifndef SHT3X_I2C_ADDRESS
+#define SHT3X_I2C_ADDRESS               0x00    // 0x00 means auto
+#endif
+
+#if SHT3X_I2C_SUPPORT
+#undef I2C_SUPPORT
+#define I2C_SUPPORT                     1
+#endif
+
 //------------------------------------------------------------------------------
 // SI7021 temperature & humidity sensor
 // Enable support by passing SI7021_SUPPORT=1 build flag
@@ -410,3 +429,7 @@
 #if SI7021_SUPPORT
     #include "sensors/SI7021Sensor.h"
 #endif
+
+#if SHT3X_I2C_SUPPORT
+    #include "sensors/SHT3XI2CSensor.h"
+#endif

code/espurna/sensor.ino

@@ -337,6 +337,14 @@ void _sensorInit() {
     }
     #endif
 
+    #if SHT3X_I2C_SUPPORT
+    {
+        SHT3XI2CSensor * sensor = new SHT3XI2CSensor();
+        sensor->setAddress(SHT3X_I2C_ADDRESS);
+        _sensorRegister(sensor);
+    }
+    #endif
+
     #if SI7021_SUPPORT
     {
         SI7021Sensor * sensor = new SI7021Sensor();

code/espurna/sensors/SHT3XI2CSensor.h

@@ -0,0 +1,137 @@
+// -----------------------------------------------------------------------------
+// SHT3X Sensor over I2C (Wemos)
+// Copyright (C) 2017 by Xose Pérez <xose dot perez at gmail dot com>
+// -----------------------------------------------------------------------------
+
+#pragma once
+
+#include "Arduino.h"
+#include "BaseSensor.h"
+#if I2C_USE_BRZO
+#include <brzo_i2c.h>
+#else
+#include <Wire.h>
+#endif
+
+class SHT3XI2CSensor : public BaseSensor {
+
+    public:
+
+        // ---------------------------------------------------------------------
+        // Public
+        // ---------------------------------------------------------------------
+
+        SHT3XI2CSensor(): BaseSensor() {
+            _sensor_id = SENSOR_SHT3X_I2C_ID;
+        }
+
+        // ---------------------------------------------------------------------
+
+        void setAddress(unsigned char address) {
+            if (_address == address) return;
+            _address = address;
+            _dirty = true;
+        }
+
+        // ---------------------------------------------------------------------
+
+        unsigned char getAddress() {
+            return _address;
+        }
+
+        // ---------------------------------------------------------------------
+        // Sensor API
+        // ---------------------------------------------------------------------
+
+        // Initialization method, must be idempotent
+        void begin() {
+
+            if (!_dirty) return;
+            _dirty = false;
+
+            // I2C auto-discover
+            unsigned char addresses[] = {0x45};
+            _address = lock_i2c(_address, sizeof(addresses), addresses);
+            if (_address == 0) return;
+
+        }
+
+        // Descriptive name of the sensor
+        String description() {
+            char buffer[25];
+            snprintf(buffer, sizeof(buffer), "SHT3X @ I2C (0x%02X)", _address);
+            return String(buffer);
+        }
+
+        // Descriptive name of the slot # index
+        String slot(unsigned char index) {
+            return description();
+        }
+
+        // Type for slot # index
+        magnitude_t type(unsigned char index) {
+            if (index < _count) {
+                _error = SENSOR_ERROR_OK;
+                if (index == 0) return MAGNITUDE_TEMPERATURE;
+                if (index == 1) return MAGNITUDE_HUMIDITY;
+            }
+            _error = SENSOR_ERROR_OUT_OF_RANGE;
+            return MAGNITUDE_NONE;
+        }
+
+        // Pre-read hook (usually to populate registers with up-to-date data)
+        void pre() {
+
+            unsigned int buffer[6];
+
+            #if I2C_USE_BRZO
+                buffer[0] = 0x2C;
+                buffer[1] = 0x06;
+                brzo_i2c_start_transaction(_address, I2C_SCL_FREQUENCY);
+                brzo_i2c_write(buffer, 2, false);
+            #else
+                Wire.beginTransmission(_address);
+                Wire.write(0x2C);
+                Wire.write(0x06);
+                if (Wire.endTransmission() != 0) {
+                    _error = SENSOR_ERROR_TIMEOUT;
+                    return;
+                }
+            #endif
+
+            delay(500);
+
+            #if I2C_USE_BRZO
+                brzo_i2c_read(buffer, 6, false);
+                brzo_i2c_end_transaction();
+            #else
+                Wire.requestFrom(_address, (unsigned char) 6);
+                for (int i=0; i<6; i++) buffer[i] = Wire.read();
+                delay(50);
+                if (Wire.available() != 0) {
+                    _error = SENSOR_ERROR_CRC;
+                    return;
+                }
+            #endif
+
+            // cTemp msb, cTemp lsb, cTemp crc, humidity msb, humidity lsb, humidity crc
+            _temperature = ((((buffer[0] * 256.0) + buffer[1]) * 175) / 65535.0) - 45;
+            _humidity = ((((buffer[3] * 256.0) + buffer[4]) * 100) / 65535.0);
+
+        }
+
+        // Current value for slot # index
+        double value(unsigned char index) {
+            _error = SENSOR_ERROR_OK;
+            if (index == 0) return _temperature;
+            if (index == 1) return _humidity;
+            _error = SENSOR_ERROR_OUT_OF_RANGE;
+            return 0;
+        }
+
+    protected:
+
+        double _temperature = 0;
+        unsigned char _humidity = 0;
+
+};