Implemented variable VREF for DAC and ADC

hardware/VREF.c

@@ -0,0 +1,30 @@
+#include "VREF.h"
+
+uint8_t adcReference = CONFIG_ADC_REF;
+uint8_t dacReference = CONFIG_DAC_REF;
+
+void VREF_init(void) {
+    //DDRD |= _BV(7);
+    DDRD = 0xFF;
+
+    TCCR2A = _BV(WGM20) |
+             _BV(WGM21) |
+             _BV(COM2A1)|
+             _BV(COM2B1);   
+
+    TCCR2B = _BV(CS20);
+
+    OCR2A = adcReference;
+    OCR2B = dacReference;
+}
+
+
+void vref_setADC(uint8_t value) {
+	adcReference = value;
+	OCR2A = adcReference;
+}
+
+void vref_setDAC(uint8_t value) {
+	dacReference = value;
+	OCR2B = dacReference;
+}