Wired-FM, a novel distributed digital single-wire field bus
Hamid Fahim Rezaei, Anton Kruger · 2012
Widely-used busses such as I2C, SPI, CAN, and others use time division for medium access. In this paper, we explore a novel bus technique, which we call Wired-FM. Wired-FM is an all-digital bus that uses a single wire an implied ground for signalling. In the rest state the bus is pulled high and nodes signal by pulling the bus low through a Wired-NOR connection. Wired-FM allows for concurrent transmissions between multiple pairs of nodes. Traditional busses aim for error free transmission, but in Wired-FM, concurrent transmitters can/will interfere. Wired-FM has similarities with traditional FM, but since the NOR operation is highly non-linear, traditional FM-style detection performs poorly. In the manuscript we present an effective detection algorithm for Wired-FM. The algorithm allows for error-free concurrent transmissions. We used extensive simulations to validate the concept and demonstrate that an alldigital, low data rate, fully distributed bus protocol which operates on single wire, and allows for concurrent transmissions, is possible using Wired-FM.