"I miss the team, and I hope to return as quickly as possible," the 2005 Ballon d'Or winner said.
Ronaldinho said he had fully recovered from the thigh injury that has kept him out of action since March, adding: "I really want to take part in the Olympic Games."
He also said that he had been working hard on his fitness level, training everyday during his holidays in southern Brazil.
The 28-year-old, who was named FIFA World Player of the Year in 2005 and 2006, has had a difficult season with the Spanish giants, failing to find the form that helped the club to Liga and Champions League glory.
Ronaldinho is under contract until 2010, but has been linked with a number of clubs, including the Premier League's Manchester City.