This is a library for use with the Si4463 radio IC from Silicon Labs, used (or will soon be) in some of my projects. The Si4463 is configurable in a ton of different ways with options for modulation, packet format, CRC algorithms and has a high output power of up to +20dBm (100mW). The Si4463 is used in a number of pre-made modules like the HopeRF RFM26W and Coral RF N540AS. The whole range of Si446x transceivers should also work with this library.
This library configures the chip to send and receive variable length packets of up to 128 bytes and uses callback functions for when events occur, such as receiving a new packet and completing a packet transmission. The callback functions run straight from the interrupt routine allowing the program to react much faster to events than if the library was polled.