// Error codes used instead of FAILURE in new code (as negative numbers)
-#define RPP_EINVAL 2
-#define RPP_EBUSY 3
-#define RPP_ENOMEM 4
-#define RPP_ENODATA 5
+#define RPP_EINVAL 2 /**< Input value error */
+#define RPP_EBUSY 3 /**< Hardware is busy */
+#define RPP_ENOMEM 4 /**< Not enough memory */
+#define RPP_ENODATA 5 /**< No data were reveived */
// Note: Sadly <stdint.h> is not available with CCS tools.
#ifdef __GNUC__