This series of articles introduces the MIPI standards. This is the first article, mainly introducing the MIPI Alliance and its series of specifications, as well as some related applications, to provide a comprehensive understanding of MIPI. Subsequent articles will provide detailed introductions to each part.
1. MIPI Overview
The MIPI Alliance, or Mobile Industry Processor Interface (MIPI), is an open standard and specification initiated by the MIPI Alliance for mobile application processors.
The MIPI Alliance is an open membership organization. Established in July 2003 by four companies: Texas Instruments (TI), STMicroelectronics, ARM from the UK, and Nokia from Finland. The MIPI Alliance aims to promote the standardization of mobile application processor interfaces.
The MIPI Alliance encourages all companies in the mobile industry to join, including: mobile device manufacturers, semiconductor manufacturers, software vendors, system suppliers, peripheral device manufacturers, intellectual property providers, and other companies.
Currently, the official website shows that it has over 310 members, divided into Adopter and Contributor categories.
The focus of the MIPI Alliance is to design and promote hardware and software interfaces to simplify the integration of built-in components in devices, from antennas and modems to peripheral devices and application processors. The MIPI Alliance has established all specifications to meet the stringent operational conditions required for mobile devices: high bandwidth performance, low power consumption, and low electromagnetic interference.
Every smartphone on the market currently uses at least one MIPI Alliance specification. In addition, tablets, laptops, and other devices also use MIPI Alliance specifications. These specifications can be used to integrate 4G/LTE radios and Wi-Fi modems, application processors, and peripherals such as high-resolution cameras, 4K ultra-high-definition displays, high-definition audio components, batteries, microphones, and sensors, etc.
As mobile connectivity becomes more prevalent in business and society, more and more industries are leveraging mobile technologies in their designs. These “mobile-influenced” industries, such as the automotive industry and the Internet of Things, also benefit from the interface specifications provided by the MIPI Alliance. Automotive manufacturers are using these interfaces to integrate various components for safety and infotainment applications, as well as advanced driver assistance systems (ADAS). IoT vendors are using these specifications to build a full range of connected devices, from single-function products to feature-rich wearable devices and complex robotic systems.
2. Working Groups
The MIPI Alliance specifications serve six basic application areas: physical layer, multimedia, chip-to-chip or interprocessor communications (IPC), control/data, and debug/trace and software. These specifications are offered as separate interfaces, allowing companies to adopt specifications that meet their specific needs.
The MIPI Alliance working groups are the core of the organization. It is these target groups that develop the MIPI specifications. The organization currently has several working groups spanning mobile device design. The specifications are open to Founder, Promoter, and Contributor member companies. Adopter members do not participate in working groups, but they can use the final specifications.
The MIPI Alliance specifications are developed by technical working groups focusing on specific market needs for interface technologies. Participants in each working group are international experts in the field. Participants typically come from semiconductor companies, software vendors, IP providers, peripheral device manufacturers, testing laboratories, and OEMs of end products, etc.
The technical working groups are formed by the MIPI Alliance board based on internal survey groups or discussion groups. Once a working group is established, it will create a development roadmap and timeline to facilitate thorough dialogue and discussion during the drafting of specifications.
The current working groups are as follows:
3. Specifications Overview
The MIPI Alliance specifications provide six types of interface requirements in devices: physical layer, multimedia, chip-to-chip/interprocessor communications (IPC), device control and data management, system debugging, and software integration.
Each specification is optimized to meet three basic performance characteristics:
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Low power consumption to extend battery life,
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High bandwidth to enable feature-rich, data-intensive applications, and
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Low electromagnetic interference (EMI) to minimize interference between radio and device subsystems.
The MIPI Alliance offers its specifications as separate interfaces, allowing companies to use those interfaces that suit their specific needs. Vendors can apply the interfaces to their advanced features to provide additional value or differentiate their products.
3.1. Physical Layers
PHY is at the core of any interconnection solution. The MIPI Alliance provides three high-performance and cost-optimized physical layer series: MIPI D-PHY, MIPI M-PHY, and MIPI C-PHY (actually four, A-PHY is under development and expected to be released by the end of 2019). Companies can apply the specifications to support various protocol layers and applications for smartphones and mobile connected devices, such as tablets, laptops, automotive, robotic systems, wearable devices, and other endpoints in the Internet of Things.
MIPI D-PHY is primarily used to connect cameras and displays to application processors. MIPI M-PHY supports multimedia and chip-to-chip/interprocessor communications. MIPI C-PHY supports cameras and displays. Each PHY meets the stringent requirements for high performance, low power operation, and low electromagnetic interference (EMI) interfaces.
The latest specifications are as follows:
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MIPI C-PHY℠ v1.2, 28-Mar-2017
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MIPI D-PHY℠ v2.1, 28-Mar-2017
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MIPI M-PHY® v4.1, 28-Mar-2017
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MIPI HSI℠ v1.01, MIPI High-Speed Synchronous Serial Interface, 25-Jan-2009
3.2. Multimedia
This section includes Audio, Camera and Imaging, Display and Touch, detailed as follows:
For the audio section, the MIPI Alliance provides two interfaces, MIPI SLIMbus and MIPI SoundWire, to simplify the integration of various audio components in devices such as smartphones, PCs, and automobiles.MIPI SLIMbus is primarily used in mobile devices to transmit audio for large components, while MIPI SoundWire is suitable for a unified interface for small audio peripherals.
MIPI SLIMbus and MIPI SoundWire are implemented on CMOS I/O. Each interface uses a two-wire hardware and transmission interface, supporting embedded control and data channels, multi-clock systems, synchronous and asynchronous modes, PCM and PDM formats, as well as embedded interrupts, wake-up, and clock stop.
The latest specifications for the audio section are as follows:
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MIPI SLIMbus® v2.0, 18-Nov-2015
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MIPI SoundWire® v1.1, 22-Aug-2016
The MIPI Alliance provides camera and imaging interfaces, as well as a standardized camera command set. Each can be used to bring high-resolution imaging, rich colors, and advanced video capabilities to smartphones, tablets, cars, video game devices, camera drones, wearable devices, and other products.
MIPI Camera Serial Interface 2 (MIPI CSI-2) operates on the MIPI C-PHY and/or MIPI D-PHY physical layers. MIPI CSI-2 is widely used in the mobile domain. It is primarily used for point-to-point image and video transmission between cameras and host devices.
MIPI Camera Command Set (MIPI CCS) defines a set of standard camera command specifications for implementing and controlling image sensors, simplifying the configuration of image sensors in mobile devices.
MIPI Camera Serial Interface 3 (MIPI CSI-3) operates on the MIPI UniPro transport layer based on the MIPI M-PHY physical layer.
The latest specifications for the Camera and Imaging section are as follows:
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MIPI CCS℠ v1.0, MIPI Camera Command Set, 24-Oct-2017
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MIPI CSI-2℠ v2.1, MIPI Camera Serial Interface 2, 9-Apr-2018
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MIPI CSI-3℠ v1.1, MIPI Camera Serial Interface 3, 12-Mar-2014
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MIPI CPI℠ v1.0, MIPI Camera Parallel Interface, 23-Mar-2004
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MIPI CSI℠ v1.0, MIPI Camera Serial Interface, 23-Mar-2004
The MIPI Alliance provides two display and touch specifications, MIPI DSI and MIPI DSI-2, for connecting displays or multiple displays to application processors. These options allow designers to flexibly support various integration methods, depending on the type of display technology used and the desired configuration to meet current or future market needs.
The MIPI Alliance display specifications are used for smartphones, tablets, and other mobile devices. The specifications are also used for automotive dashboards and in-car infotainment displays, smart meters, video game devices, wearable devices such as smartwatches, and virtual or augmented reality headsets, etc.
The latest specifications for the Display and Touch section are as follows:
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MIPI ALI3C℠ v1.0, MIPI Adaptation Layer for I3C, 09-Apr-2018
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MIPI DBI℠ v1.0, MIPI Display Bus Interface, 22-Mar-2004
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MIPI DBI-2℠, MIPI Display Bus Interface 2, 16-Nov-2005
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MIPI DCS℠ v1.4, MIPI Display Command Set, 2-May-2018
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MIPI DPI-2℠ v2.00, MIPI Display Pixel Interface 2, 23-Jan-2006
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MIPI DPI℠ v1.0, MIPI Display Pixel Interface, 23-Mar-2004
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MIPI DSI-2℠ v1.1, MIPI Display Serial Interface 2, 2-May-2018
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MIPI DSI℠ v1.3.1, MIPI Display Serial Interface, 17-Dec-2015
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MIPI SDF℠ v1.0, MIPI Stereoscopic Display Formats, 14-Mar-2012
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MIPI TCS℠ v1.0, MIPI Touch Command Set, 09-Apr-2018
3.3. Chip-to-Chip/IPC
The MIPI Alliance has a series of high-speed protocols for chip-to-chip or interprocessor communications (IPC) between 4G/LTE modems, Wi-Fi modems, companion bridge chips, and application processors. Each specification meets the specific needs for high performance, low power consumption, and low electromagnetic interference (EMI) in mobile connected devices.
MIPI UniPro is primarily used for application-agnostic transport layers in chip-to-chip or IPC in traditional or modular device architectures. MIPI DigRF is a high-speed interface for connecting RFICs and baseband processors. MIPI LLI provides point-to-point interfaces between application processors and modems/baseband processors. It allows baseband processors to access dedicated DRAM memory of the application processor for baseband processor operations without requiring the baseband processor to have its own dedicated DRAM chip.
The latest specifications are as follows:
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MIPI DigRF℠ v4 v1.2, 4-Feb-2014
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MIPI Dual Mode℠ 2.5G / 3G RFIC v3.09.06, 5-Aug-2011
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MIPI LLI℠ v2.1, MIPI Low Latency Interface, 7-Nov-2014
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MIPI UniPro℠ v1.8, 11-Jan-2018
3.4. Control and Data
The MIPI Alliance has a series of interface specifications for managing low-speed component protocol layers. Designers can use these specifications to control components and manage the use and flow of operational data.
The MIPI RF Front-End Control Interface (RFFE) simplifies the integration of complex RF front-end devices. The MIPI Battery Interface provides a “smart” interface to enhance battery performance and safety. The MIPI System Power Management connects SoCs to one or more peripheral chips for power management control and data buses. eTrak – Envelope Tracking Interface enhances RF power efficiency. MIPI I3C and I3C Basic are bus interfaces for connecting sensors, processors, and other peripherals in mobile, IoT, and automotive systems.The MIPI Virtual GPIO Interface (VGI) is a general architecture for sideband signals and low-speed messaging in mobile systems.
The latest specifications are as follows:
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MIPI BIF℠ v1.1.1, MIPI Battery Interface, 10-Mar-2015
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MIPI BIF℠ Hardware Abstraction Layer v1.0, 22-May-2013
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MIPI eTrak℠ v1.1, MIPI Envelope Tracking Interface, 10-Sep-2014
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MIPI I3C® v1.0, MIPI Improved Inter Integrated Circuit, 31-Dec-2016
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MIPI I3C Basic℠ v1.0, 8-Oct-2018
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MIPI RFFE℠ v2.1, MIPI RF Front-End Control Interface, 23-April-2018
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MIPI SPMI℠ v2.0, MIPI System Power Management, 28-Aug-2012
3.5. Debug and Trace
The MIPI Alliance has a series of specifications that can be used to debug connected components in mobile devices, such as endpoints in the Internet of Things. They can also be used to debug application processors, modems, device controllers, power management devices, etc.
The latest specifications are as follows:
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MIPI Gigabit Debug for IPS v1.0, 29-Jul-2016
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MIPI Gigabit Debug for USB v1.1, 2-Mar-2018
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MIPI HTI v1.0, MIPI High-Speed Trace Interface (MIPI HTI), 29-Jul-2016
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MIPI NIDnT℠ v1.2, MIPI Narrow Interface for Debug and Test, 5-Dec-2017
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MIPI PTI℠ v2.0, MIPI Parallel Trace Interface, 12-Oct-2011
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MIPI SPP℠ v1.0, MIPI SneakPeek Protocol, 3-Aug-2015
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MIPI STP℠ v2.2, MIPI System Trace Protocol, 11-Feb-2016
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MIPI SyS-T℠ v1.0, MIPI System Software – Trace, 9-Apr-2018
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MIPI TWP℠ v1.1, MIPI Trace Wrapper Protocol, 18-Dec-2014
3.6. Software Integration
The MIPI Alliance has developed a series of specifications to simplify the software integration of components in mobile devices, as well as mobile connectivity for other markets such as automotive systems and IoT. The software specifications include infrastructure frameworks and a series of interface specifications that unify the software discovery and configuration of MIPI Alliance protocols. These solutions enable developers to manage various components from different vendors using a common software approach when loading drivers. This approach not only simplifies software integration but also reduces development costs.
The latest specifications are as follows:
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MIPI DDB℠ v1.0, MIPI Device Descriptor Block, 12-Oct-2011
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MIPI DisCo℠ v1.0, MIPI Discovery and Configuration (DisCo) Specification, 28-Dec-2016
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MIPI DisCo Specification for NIDnT, 24-Oct-2017
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MIPI DisCo Specification for SoundWire v1.0, 28-Mar-2017
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MIPI I3C℠ HCI℠ v1.0, 29-Sep-2017
Above is an introduction to the MIPI Alliance, Working Groups, and the six basic application areas related specifications. Subsequent articles will provide related introductions to the specific specifications of each area.
Source: Hardware Assistant