To start off, there is something very important to understand: "ages" are something that are created to allow people to understand extended periods of time (historical periodizations to be exact.) It is not as if the 1500's came around and all the residents of the Italian peninsula changed their outfits and made adjustments to their homes. They didn't know they lived in the High Renaissance. The Renaissance is typically recognized to start in the 14th century, yet under different historical periodizations, the Middle Ages runs from the 5th to the 15th century.

Many Italians, including Dante and Petrarch, wrote of the Classical Age as a Golden Age due to the power the people of the peninsula held as opposed to their present day counterparts. Machiavelli, was no different than his counterparts (even though they lived before him.)

The terms crafted to define eras of time are often fought about and argued by historians, the Dark Ages probably being one of the most debated ones. Even the Renaissance is a complicated period to define (example, Dante was born in the 13th century and Machiavelli in the 15th. The changes in Italian society were HUGE between both centuries.)

Scholars, such as Dante, were aware of figures such as Charlemagne, and he did in fact write about him and other Holy Roman Emperors from the Dark Ages. Petrarch makes a reference to Charlemagne in one of his sonnets(27):

"The successor of Charles, who adorns his brow with one of the crowns of his ancestors, has already taken arms to break the horns of Babylon and of whoever bears her name;"

This sonnet is a reference to the crusade of 14th century and how King Phillip, successor of Charlemagne as a French ruler, should look up to him for Christian inspiration in order to attack the enemies of Christianity.

Scholars did pay attention to the Dark Ages, but they paid attention to the Golden Age of Rome even more. It was a close topic to them since Italian City States were under constant threat of foreign powers (French, Spanish, Turkish) and looked to their glorious unified past for inspiration.

The Dark Ages were seen as mostly an extension of Roman rule. The power of the church, seen by some such as Dante, as Roman rule outside of their time.

More references to the Dark Ages can be found in the following works:

Dante Alighieri, De Monarchia (1318)- writings about Roman law and how it was related to Christianity. Its extension of power into other periods of time is discussed.

Petrarch, Il Canzoniere (1374)- a collection of Petrarch's writings, some which make references to figures and events from the Dark Ages.

Hans Hummer's "Politics and Power in Early Medieval Europe: Alsace and the Frankish Realm, 600-1000." A good book to understand historiography and some of the debates about terms like the Dark Ages.