Simple Sensor Interface protocol: Difference between revisions

Revision as of 14:45, 23 June 2013

Revision as of 09:49, 21 January 2014

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The '''SSI''' ("'''Simple Sensor Interface'''") protocol is a simple communications protocol designed for data transfer between computers or user terminals and smart sensors. The SSI protocol is an [[Application layer]] protocol as in the [[OSI model]].

The SSI protocol has been developed jointly by [[Nokia]], [[Vaisala]], [[Suunto]], Ionific, Mermit and [[University of Oulu]]. Currently SSI is being developed within the [http://www.mimosa-fp6.com/ Mimosa project] which is a, part of the [[European Union]] [[Framework Programmes onfor Research and Technological Development]].

The SSI protocol is used in point-to-point communications over [[UART]] and networking [[nanoIP]] applications. SSI also provides polling sensors and streaming sensor data. For [[RFID]] sensor tags SSI specifies memory map for sensor data.

The criteria for SSI protocol development are:

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=== Networking SSI ===

SSI networking in a variable environment is done using [[nanoIP]]. In a typical case using SSI, an individual message is not important, and so nanoUDP (simplified [[User Datagram Protocol|UDP]] defined by nanoIP) is used as the message format. If individual messages are important, nanoTCP can be used, as it provides flow control and retransmission at a cost of message size and increase in network traffic.

A nanoUDP message consists of a 5-byte nanoUDP header, an n-byte message payload and an optional 2-byte CRC checksum. The header consists of one protocol byte, a 2-byte message length (total length, including header and CRC), a 1-byte source port and a 1-byte destination port number. The destination port number should be 0x28 for SSI messages.