The Serial Low-power Inter-chip Media Bus (SLIMbus) is a standard interface between baseband or application processors and peripheral components in mobile terminals.
It was developed within the MIPI Alliance, founded by ARM, Nokia, STMicroelectronics and Texas Instruments.
SLIMbus is implemented as a synchronous 2-wire, configurable Time Division Multiplexed (TDM) frame structure.
The Manager Device is responsible for configuring SLIMbus, and performs bus administration (administration of Components and Devices, bus configuration, and dynamic channel allocation) and is typically located in a baseband or application processor rather than in a peripheral component.
The Interface Device provides bus management services, monitors the Physical Layer for errors, reports information about the status of a SLIMbus Component, and otherwise manages the Component such that the Devices within it will function properly on the bus.
A SLIMbus Port (P) provides the connection path for data flow between Devices.
Port capabilities vary depending upon the Device and are to be specified in the Component data sheet.
All SLIMbus Devices use DATA and CLK to synchronize with the bus configuration in use, to receive or transmit messages and data, and to implement bus arbitration, collision detection, and contention resolution between devices.
For all SLIMbus Components, the DATA line is bidirectional, and carries all information sent or received on the bus using Non-Return-to-Zero Inverted (NRZI) encoding.
A Cell is defined as a region of the DATA signal that is bounded by two consecutive positive edges of the CLK line and holds a single bit of information.
The active Framer writes all Framing Information to the Data line at the appropriate time.
The Subframe configuration used can be dynamically changed depending upon the data flow requirements of the applications being supported at the time.
The Control Space carries bus configuration and synchronization information as well as inter-Device Message communication.
The Control Space may be dynamically programmed to take as much of the SLIMbus bandwidth as required, even up to 100% at times.
The format of Control Space is determined by a 5-bit Subframe mode identifier transmitted in the Framing Information word.
Adding the limitations that the number of control Slots must be less than the Subframe length produces 26 valid combinations.
A special encoding for "100% Control Space", in which case the Subframe length is unimportant, produces 27 valid modes.
Segments repeat at known intervals and behave as virtual bus's with their own bandwidth guarantee and latency.
Flow Control in the Channel, if needed, depends on the Devices and the type of Data involved.
The Manager and/or Framer Device shown in the upper left SLIMbus Component can also be incorporated into baseband and/or applications processors typically used to build mobile terminals.
Figure 8 below shows a conceptual view of a possible real world SLIMbus system.