grove: sliding potentiometer

Signed-off-by: Mihai Tudor Panu <mihai.t.panu@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/grove/grove.cxx

@@ -160,3 +160,36 @@ float GroveRotary::rel_rad()
 {
     return GroveRotary::rel_deg() * M_PI / 180.0;
 }
+
+//// GroveSlide ////
+
+GroveSlide::GroveSlide(unsigned int pin, float ref_voltage)
+{
+    mraa_init();
+    m_aio = mraa_aio_init(pin);
+    m_ref_voltage = ref_voltage;
+    m_name = "Slide Potentiometer";
+}
+
+GroveSlide::~GroveSlide()
+{
+    mraa_aio_close(m_aio);
+}
+
+float GroveSlide::raw_value()
+{
+    return (float) mraa_aio_read(m_aio);
+}
+
+float GroveSlide::voltage_value()
+{
+    // conversion to Volts
+    float a = GroveSlide::raw_value();
+    a = m_ref_voltage * a / 1023.0 ;
+    return a;
+}
+
+float GroveSlide::ref_voltage()
+{
+    return m_ref_voltage;
+}