Contiki is the software that runs in wireless micro controllers, and let’s you connect securely to the Internet. This might a good option for your next IoT project. In the video below, Adam Dunkels, the primary author and founder of the Contiki project explains what Contiki is and what it does in a video interview. It’s quite long at 21 minutes, but the video does a good job of covering all the bases around Contiki.
Contiki is available on many platforms — it runs on MCUs from 8051 to AVR, MSP430 and ARM Cortex-M0 based chips too.
Below are a set of videos that shows the various possibilities of wireless sensor network nodes and about Cooja (a Contiki network simulator).