Do I have to give police my phone passcode?

This is one of the areas where I'd rather tell you the law is contested than give you a clean answer that might be wrong.

The argument against compelled disclosure runs through the Fifth Amendment: a passcode exists in your mind, and requiring you to produce it compels you to reveal the contents of your own thoughts, which is testimonial. Courts have found that persuasive in a number of cases.

The State's counterargument is that where the government already knows the device belongs to you and knows what's on it, producing the code adds nothing it doesn't already have — sometimes called the foregone conclusion doctrine.

Florida authority in this area has moved, and courts around the country have split.

What's practical rather than legal: you're not required to volunteer it, and a request is not an order. If there's a court order compelling production, that's a different situation with real consequences for refusing — and one to address with counsel rather than alone.