SLIMbus Interface: Protocol Basics and Advantages

This page covers the basics of the SLIMbus interface protocol and highlights its benefits and advantages.

Introduction:

The SLIMbus specifications are developed and managed by the MIPI Alliance, a group of companies that includes Intel, NXP, Motorola, Infineon, Texas Instruments, Marvell Semiconductor, and Freescale Semiconductor, among others. The latest specifications were released under version 2.0 in November 2015.

The SLIMbus interface supports multiple digital audio components simultaneously, carrying various digital audio streams at varying sampling rates and bit widths.

What is SLIMbus Protocol?

SLIMbus stands for Serial Low power Inter-chip Media Bus. This interface is designed to transport audio between cellular modems and application processors, interfacing with peripherals such as Bluetooth, FM radio, audio codecs, and audio subsystems like microphones and speakers.

It serves as a complementary protocol to the SoundWire interface. SLIMbus is a two-wire synchronous interface that utilizes a TDM (Time Division Multiplexed) frame structure. It connects multiple components in a multi-drop topology using DATA and CLK lines.

The following are key features of the SLIMbus interface protocol:

• Synchronous 2-Wire (DATA, Clock) Interface
• Flexible TDM frame structure, carrying audio, data, bus, and device control on a single bus
• SLIMbus frame consists of cells, slots, frames, subframes, and superframes.
• The DATA line can be used for both data channels and control channels.
• Supports multiple, concurrent sample rates on a single bus
• Uses dedicated messages for bus management, data transfer, and device control

Benefits or Advantages of SLIMbus

Here are the key benefits and advantages of using SLIMbus:

• Used in 5G Smartphones: SLIMbus is used in the latest series of 5G smartphones to interface with larger-sized audio components.
• High Performance: It offers high performance for demanding audio applications.
• Low Power Consumption: It consumes low power, helping to preserve battery life in mobile devices.
• Reduced EMI: SLIMbus introduces low EMI (electromagnetic interference) to minimize interference between radios and other interface device sub-systems.
• High Bandwidth: It offers high bandwidth, supporting data-intensive applications with more features.
• Replaces Legacy Interfaces: SLIMbus replaces legacy digital interfaces used for audio interfacing, such as PCM (Pulse Code Modulation), I2S, and SSI (Synchronous Serial Interface).
• Replaces Digital Control Buses: It also replaces digital control buses, including UART, SPI, I2C, GPIO, microWire, etc. This offers greater flexibility and simplicity.
• Reduced Pin Count: It reduces pin count, leading to lower overall cost in implementation.
• Bus Arbitration: It supports bus arbitration, contention resolution, and collision detection between devices on the bus.

Refer also to the advantages or benefits of the SoundWire interface protocol, the Unipro interface protocol, and the M-PHY Physical layer.

For further reading, explore the advantages and disadvantages of the following interface protocols: UART, SPI, I2C, I2S, Serial interface, and Parallel interface.