In most instances, the Office of the Public Defender becomes the default counsel for a person who cannot afford to hire their own lawyer. Try http://pd13.state.fl.us/
As an alternative, there are a number of excellent criminal defense lawyers who list here on Avvo.com, who are licensed to practice law in FL. Review their profiles, select a few and call them for a consultation. Good luck.
Since I do not practice law in your State, this answer is provided solely for informational purposes only, for you to use as a starting point when speaking directly with a lawyer in your State. This answer does not constitute legal advice, create an attorney-client relationship, or constitute attorney advertising. I urge you to immediately contact an experienced criminal defense lawyer admitted to practice law in your State before you make any decisions about this case.
I cannot thing of a quality attorney who would take on an Armed Robbery case Pro Bono. There would have to be some compelling issue behind the case for an attorney to do so. Simply claiming you are innocent would not be a satisfactory reason.
Usually when I field inquires like this, it is from people who think they are to good for the public defender, but to cheap to hire an attorney.
Considering the seriousness of your charge, you should be looking to hire the best lawyer possible, not save money by thinking someone would want to take on a case for free.
I agree with Mr. Hornsby in that there are very, very few, if any, quality defense attorneys that would take a case as serious as your pro bono. You best bet is to stick with the public defender's office if you cannot spend at least $10,000 to find a good private attorney.