Birchas Shechiyanu

Rashi explains the words of vedoy maaser לא שכחתי, as referring to the blessing.  The question is that the blessings are only rabbinic so why would it be mentioned in the Torah?  The Shem M'Shmuel quotes from his father (Avne Nezer) that Rashi is referring to the blessing of shechiyanu. The Ri Migash response 203 says shechiyanu is mandated from the Torah.  The main support is from Eiruvin (40b) that on the regalim one is obligated to say a shechiyanu as a biblical law.  However, the Gemorah doesn’t tell us the source for the law.  In fact, the Ravyah (383) asks what the source of this law is? Possibly we may suggest that this obligation is learnt from the verse of “mekrah kodesh.”  The Ramban in Leviticus (23:2) explains the possuk to mean that there is an obligation to honor the day by calling it holy.  This is fulfilled through the recitation of shechiyanu.  (This could be the source for Rashi in Shevous (13a) that there is a Torah obligation to mention the day of Yom Kippur in the prayer services see Tosfos that questions the source of Rashi.)  However, this explanation of the Gemorah in Eiruvin makes the answer of the Avne Nezer insufficient because we only find shechiyanu on a biblical level in the context of a holiday. 

The Gelyonah Hashas asks why is there no shechiyanu on Rosh Chodesh and Shabbos? It could be the obligation of shechiyanu is dependent on the law of aliyah laregel.  Only at the time of a Tom Tov with the simcha of aliyah laregel is shechiyanu recited.  However, he answers that the obligation is fulfilled by the blessing of kiddash levana.  His answer is unclear for what does the birchos halevana have to do with the blessing of shechiyanu?