Tokyo falls 0.3%
A weak yen lost its luster on Friday as Japan's benchmark Nikkei index broke a 9-day winning streak to dip below the flatline. Trade was subdued as investors stayed on the sidelines ahead of Yellen's speech.
"The Nikkei's rally has stalled, along with the dollar-yen as it consolidates near the 104 mark. It's clear the pair and the index are both waiting for a catalyst and we are unlikely to see any big moves until Janet Yellen's speech," IG's market strategist Stan Shamu wrote in a note.
Among gainers, pharmaceutical firm Shionogi held steady at a 2 percent gain while Shinsei Bank advanced 1 percent after the Nikkei business daily said the lender is planning to bid for Citigroup's Japanese retail bank operations.
Exporter stocks were mixed as the currency traded at 103.7 against the U.S. dollar. Nissan Motor added 0.3 percent while Sony pared gains to close up 0.1 percent.
Read MoreForget Japan's shrinking economy: property looks hot
Sydney up 0.1%
Australia's benchmark S&P ASX 200 index eked out modest gains on Friday to extend gains into the seventh session as investors continue to digest earnings results.
Oil and gas producer Santos advanced nearly 4 percent after beating forecasts with a 3 percent rise in first-half core profit.
Mineral sands miner Iluka Resources scaled 3.4 percent despite reporting a nearly 70 percent fall in full-year net profit on Friday. Atlas Iron was one of the worst performers on the bourse, tanking over 8 percent after announcing a one-off charge of 25 million Australian dollars on plans to divest its Shaw River Manganese interest.
Read MoreWhy property is Hong Kong's national sport
Mainland shares up
China's Shanghai Composite Index reversed losses to close up 0.5 percent.
The outperformer for the session was pharmaceutical firm Baiyunshan, which rallied 8.5 percent. Fosun Pharmaceutical also climbed nearly 2 percent. Smaller lenders were on a roll; Hua Xia Bank and Merchants Bank rallied over 1 percent each.
Hong Kong's Hang Seng Index recouped one-third of Thursday's steep losses by trading 0.3 percent higher.
Li & Fung was in focus after reporting a 9 percent drop in interim operating profits; its shares plunged over 4 percent on Friday.
China's largest cement maker Anhui Conch gained 0.7 percent after posting a strong 60.3 percent rise in second quarter net profit.