The Spanish "OPENHEALTH PROJECT" provides some FLOSS (free libre and open source project) tools

Signove provides Antidote, an open-source IEEE 11073-20601 stack implementation.

NXP (formerly Freescale) provide software development kits (SDK) for its processors to support various aspects of IEEE 11073 PHD devices. This includes SDK for its family of ZigBee devices such as the Kinetis processors. Details can be found by searching for Beekit.