holy cow - this thing sensor supports SPI -- added SPI support

Author: gigapod

README.md

@@ -38,10 +38,17 @@ At the start of your sketch, the library header file is included using the follo
 
 Before the arduino ```setup()``` function, create a Soil Sensor object in your file with the following declaration:
 
+For I2C bus:
 ```c++
-SparkFunSoilMoistureSensor mySoilSensor; // Create an instance of the sensor class
+SparkFunSoilMoistureSensorI2C mySoilSensor; // Create an instance of the sensor class
 ```
 
+For SPI bus:
+```c++
+SparkFunSoilMoistureSensorSPI mySoilSensor; // Create an instance of the sensor class
+```
+
+
 ### Initialization
 
 In the Arduino ```setup()``` function, initialize the sensor by calling the begin method. This method is called after the Arduino `Wire` (I2C) library is initialized. 

examples/Example_01_BasicReadings/Example_01_BasicReadings.ino

@@ -11,7 +11,7 @@
 #include "SparkFun_Soil_Moisture_Sensor.h" // CTRL+Click here to get the library: http://librarymanager/All#SparkFun_Soil_Moisture_Sensor
 #include <Wire.h>
 
-SparkFunSoilMoistureSensor mySoilSensor; // Create an instance of the sensor class
+SparkFunSoilMoistureSensorI2C mySoilSensor; // Create an instance of the sensor class
 
 // Some Dev boards have their QWIIC connector on Wire or Wire1
 // This #ifdef will help this sketch work across more products

examples/Example_02_ReadingsAndLED/Example_02_ReadingsAndLED.ino

@@ -11,7 +11,7 @@
 #include "SparkFun_Soil_Moisture_Sensor.h" // CTRL+Click here to get the library: http://librarymanager/All#SparkFun_Soil_Moisture_Sensor
 #include <Wire.h>
 
-SparkFunSoilMoistureSensor mySoilSensor; // Create an instance of the sensor class
+SparkFunSoilMoistureSensorI2C mySoilSensor; // Create an instance of the sensor class
 
 // Some Dev boards have their QWIIC connector on Wire or Wire1
 // This #ifdef will help this sketch work across more products

examples/Example_03_LEDFlashMoisture/Example_03_LEDFlashMoisture.ino

@@ -14,7 +14,7 @@
 #include "SparkFun_Soil_Moisture_Sensor.h" // CTRL+Click here to get the library: http://librarymanager/All#SparkFun_Soil_Moisture_Sensor
 #include <Wire.h>
 
-SparkFunSoilMoistureSensor mySoilSensor; // Create an instance of the sensor class
+SparkFunSoilMoistureSensorI2C mySoilSensor; // Create an instance of the sensor class
 
 // The plan:
 //    The value of the sensor has the following range:

src/SparkFun_Soil_Moisture_Sensor.h

@@ -18,8 +18,15 @@
 #include <SparkFun_Toolkit.h>
 #include "sfeTk/sfeDevSoilMoisture.h"
 
-// Define our Arduino Object
-class SparkFunSoilMoistureSensor : public sfeDevSoilMoisture
+// Note:
+// The core of the implementation for this device library is in the SparkFun Toolkit object sfeDevSoilMoisture,
+// contained in the directory sfeTk. This object implements all functionality independent of the bus type, I2C or SPI.
+// The SparkFunSoilMoistureSensorI2C and SparkFunSoilMoistureSensorSPI classes below are the Arduino-specific, bus-specific
+// implementations that inherit from the core toolkit class. 
+//
+//-----------------------------------------------------------------------------------------------
+// Define our Arduino Object - I2C version
+class SparkFunSoilMoistureSensorI2C : public sfeDevSoilMoisture
 {
   public:
     /// @brief Begins the Device
@@ -45,3 +52,27 @@ class SparkFunSoilMoistureSensor : public sfeDevSoilMoisture
   private:
     sfeTkArdI2C _theI2CBus;
 };
+
+//-----------------------------------------------------------------------------------------------
+// Define our Arduino Object - SPI version
+class SparkFunSoilMoistureSensorSPI : public sfeDevSoilMoisture
+{
+  public:
+    /// @brief Begins the Device with SPI as the communication bus
+    /// @param csPin The chip select pin for the sensor
+    /// @param spiPort The SPI port to use for communication
+    /// @param spiSettings The SPI settings to use for communication
+    /// @return True if successful, false otherwise
+    bool begin(const uint8_t csPin, SPIClass &spiPort = SPI, SPISettings spiSettings = SPISettings(100000, MSBFIRST, SPI_MODE0))
+    {
+
+        // Setup Arduino SPI bus
+        _theSPIBus.init(spiPort, spiSettings, csPin, true);
+
+        // Begin the sensor and make sure it's connected.
+        return (sfeDevSoilMoisture::begin(&_theSPIBus) == kSTkErrOk );
+    }
+
+  private:
+    sfeTkArdSPI _theSPIBus;
+};

src/sfeTk/sfeDevSoilMoisture.cpp

@@ -21,7 +21,7 @@
 //---------------------------------------------------------------------
 // Core object implementation
 //---------------------------------------------------------------------
-sfeTkError_t sfeDevSoilMoisture::begin(sfeTkII2C *theBus)
+sfeTkError_t sfeDevSoilMoisture::begin(sfeTkIBus *theBus)
 {
     // Nullptr check
     if (theBus == nullptr)
@@ -30,7 +30,7 @@ sfeTkError_t sfeDevSoilMoisture::begin(sfeTkII2C *theBus)
     // Set bus pointer
     _theBus = theBus;
 
-    return _theBus->ping();
+    return kSTkErrOk;
 }
 
 //----------------------------------------------------------------------------------------

src/sfeTk/sfeDevSoilMoisture.h

@@ -33,7 +33,7 @@ class sfeDevSoilMoisture
     /// @brief Start the driver/begin connecting/comms to the device
     /// @param theBus A pointer to an I2C toolkit object
     /// @return kSTkErrOk if successful, otherwise an error code
-    sfeTkError_t begin(sfeTkII2C *theBus = nullptr);
+    sfeTkError_t begin(sfeTkIBus *theBus = nullptr);
 
     /// @brief Turns off the on-board LED
     /// @return kSTkErrOk if successful, otherwise an error code
@@ -61,7 +61,7 @@ class sfeDevSoilMoisture
     sfeTkError_t changeSensorAddress(uint8_t newAddress);
 
   protected:
-    // The I2C bus the sensor is connected to
-    sfeTkII2C *_theBus;
+    // The toolkit bus the sensor is connected to
+    sfeTkIBus *_theBus;
 
 }; // class sfeDevSoilMoisture