The Expanding Universe Of MIPI Applications

Why this interface is no longer just about mobile phones.


It’s hard to imagine today, but there was a time when mobile phones had no cameras and displays were tiny monochrome LCDs capable of displaying a phone number and not much more. The iconic Nokia 3310 announced Sept. 1, 2000, had an 84 x 48 pixel monochrome display and went on to sell 126 million units worldwide. You may still have one in your junk drawer.

By the time of the original iPhone launch in June 2007, cameras and high-quality mobile displays were becoming standard equipment on mobile phones. The preceding years were the “Wild West” of proprietary interface solutions for connecting cameras and displays to mobile processors. Standardization was needed to make sense of the chaos of sourcing these components.

The Mobile Industry Processor Interface (MIPI) Alliance was formed in 2003 to address the fragmentation in the essential video interface technologies for cameras and displays in phones. Over the years, the alliance expanded its scope to publish specifications covering physical layer, multimedia, chip-to-chip or inter-processor communications (IPC), control/data, and debug/trace and software. With the broader mission, the MIPI Alliance ultimately dropped its original longer name and “MIPI” became its name and not an acronym.

MIPI initially competed with MDDI (Mobile Display Digital Interface) for the title of industry standard. There was even a short-lived market for MDDI-to-MIPI bridge chips. Ultimately, the low power, low-latency, scalable performance of MIPI, combined with broader industry support, prevailed. Today, more than a billion phones (1.7B in 2019) and 100 million tablets ship annually with technology conforming to the MIPI standards. The inherent gravity of this success draws in more satellite opportunities.

The enormous manufacturing base which made possible high-resolution, miniaturized digital cameras for mobile phones helped fuel the rise of the Internet of Things (IoT). When you think IoT, “sensing” is one of the key attributes of these devices, and it’s MIPI-based cameras that are collecting visual data. This is creating an exponential rise in the generation of image data which is feeding rapid advancements in AI/ML training. The attractive force of the available MIPI PHY bandwidth and high-resolution data formats leveraged by cameras has drawn in more types of sensors.

With the growing mass of high resolution, low latency mobile cameras, IoT and AI/ML, the universe of MIPI applications is expanding rapidly. Today’s cars, particularly with the increasing sophistication of Advanced Driver-Assistance Systems (ADAS), are brimming with cameras and sensors. Park assist, driver monitoring, blind spot detection, night vision, vehicle security systems and more employ types of automated vision systems. These, more often than not, use MIPI to enable the improved competence of ADAS. Meanwhile, cockpits and infotainment systems feature a growing number of high-resolution displays and these too use MIPI interconnects.

Automated delivery drones, smart homes, tele-medicine, industrial robotics, commercial security, and smart cities all use MIPI-based cameras and sensors. Across all these applications, wherever there is a human interface, you’re likely to find a display connected to its host processor via MIPI. This is also true for the emerging world of AR/VR where applications demand low power, low latency and high resolution to lower the barriers to adoption.

For camera to processor interconnects, the relevant MIPI standard is CSI-2 (Camera Serial Interface 2). It is a high-speed protocol intended for point-to-point image and video transmission. Some of the features of CSI-2 include:

  • C-PHY and D-PHY support
  • 24-bit precision of pixels to enable machine learning and inferencing from superior quality images
  • Supports multi-exposure and multi-range sensor fusion for ADAS systems with up to 32 virtual channels
  • Per lane data scrambling/descrambling

With capabilities like these, it’s clear MIPI has evolved to encompass much more than the needs of mobile phones.

On the display side, the MIPI DSI-2 (Display Serial Interface 2) standard applies. The DSI-2 protocol supports ultra-high definition displays up to 8K resolution. It supports the VESA VDC-M and Display Stream Compression (DSC) standards in its transport layer. VDC-M offers up to 5:1 compression of images while maintaining visually lossless viewing. Like its companion camera protocol, DSI-2 with available DCS encoders/decoders is designed for low-power operation to enable maximum battery life in mobile and IoT devices.

If you’re designing a chip for this expanding universe of MIPI applications, Rambus has off-the-shelf reusable IP. With over a decade of MIPI experience deploying high quality, easy to use design IP. Rambus offers the industry’s leading MIPI-compliant CSI-2 and DSI-2 controllers. Partnering with top-tier MIPI PHY suppliers, such as Mixel and Samsung, Rambus solutions have enabled over 100 ASIC and over 130 FPGA MIPI designs. As with these 100s of designs, Rambus will provide a fully integrated MIPI interface with your desired PHY. With expert technical support and a full suite of customization and integration services, this will help you speed your MIPI-based system to market.

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