open source hardware for software-defined radio
Documentation is in the wiki.
For assistance with HackRF general use or development, please look at the issues on the GitHub project. This is the preferred place to ask questions so that others may locate the answer to your question in the future.
A large group of users spend time in the #hackrf IRC channel on freenode. The IRC channel is a great place for us all to learn together, but it is not a good place to request support.