DS1307: Add string based constructor for Clock

Signed-off-by: Adelin Dobre <adelin.dobre@rinftech.com>

src/ds1307/ds1307.cxx

@@ -46,6 +46,27 @@ DS1307::DS1307(int bus) : m_i2c(bus)
   }
 }
 
+DS1307::DS1307(std::string initStr) : m_i2c(nullptr), mraaIo(initStr)
+{
+  mraa_io_descriptor* descs  = mraaIo.getMraaDescriptors();
+  
+  if(!descs->i2cs[0]) {
+    throw std::invalid_argument(std::string(__FUNCTION__) +
+                                  ": mraa_i2c_init() failed");
+    return;
+  } else {
+    m_i2c = descs->i2cs[0];
+  } 
+    
+  // setup our i2c link
+  mraa::Result ret = m_i2c.address(DS1307_I2C_ADDR);
+  if (ret != mraa::SUCCESS){
+    throw std::invalid_argument(std::string(__FUNCTION__) +
+                                  ": i2c.address() failed");
+    return;
+  }
+}
+
 mraa::Result DS1307::writeBytes(uint8_t reg, uint8_t *buffer, int len)
 {
   if (!len || !buffer)

src/ds1307/ds1307.hpp

@@ -28,6 +28,7 @@
 
 #include <string>
 #include <mraa/i2c.hpp>
+#include <mraa/initio.hpp>
 
 #define DS1307_I2C_BUS     0
 #define DS1307_I2C_ADDR    0x68
@@ -77,6 +78,13 @@ namespace upm {
      * @param bus I2C bus to use
      */
     DS1307(int bus);
+    
+    /**
+     * Instantiates DS1307 Clock based on a given string.
+     *
+     * @param initStr string containing specific information for DS1307 initialization.
+     */
+    DS1307(std::string initStr);
 
     /**
      * Loads all the time values
@@ -188,6 +196,7 @@ namespace upm {
 
   private:
     mraa::I2c m_i2c;
+    mraa::MraaIo mraaIo;
   };
 }