Fix default value for day field in time register

registers.hpp

@@ -103,7 +103,7 @@ struct [[gnu::packed]] TimeReg
 	uint8_t seconds = 0;
 	uint8_t minutes = 0;
 	uint8_t hours = 0;
-	uint8_t day = 0;
+	uint8_t day = 1; // Range 1-7 according to datasheet
 	uint8_t date = 0;
 	uint8_t month_century = 0;
 	uint8_t year = 0;