An inter-device communication protocol for modular smart-objects

The ability to gather and analyze distributed data adding value to extracted information is a core concept in the Internet of Things. Smart-Objects with multi-sensor capability further enhance environmental awareness with coherent and meaningful information. In this paper we first investigate a modular architecture for multi-sensors Smart-Objects allowing to ease their customization and maintainability. Then, we introduce and detail an efficient and flexible inter-device communication protocol: flexSPI. Built on top of Serial Peripheral Interface (SPI), the proposed approach allows reducing routing overhead and enabling modularity by exploiting packet-oriented messaging. To achieve these improvements, SPI bus is completely shared between connected devices avoiding conflicts by keeping free (i.e. in input direction) the Slave Output/Master Input SOMI signal and occupying it only after proper, advanced addressing. Low power and high bandwidth characteristics of SPI bus are maintained while enabling smart features such as hotpluggability, link diagnosis, devices discovery, synchronization and master solicitation.