Electronic Products & Technology

MIPI Alliance updates CSI specs

EP&T Magazine   

Electronics Electronics

MIPI Alliance, Piscataway NJ, an international organization that develops interface specifications for mobile and mobile-influenced industries, introduced MIPI CSI-2 v1.3, a comprehensive update to its Camera Serial Interface (CSI) specification. The new specification enables manufacturers to use the CSI-2 interface to bring higher-resolution imaging capabilities, natural color representation and advanced video capabilities to smartphones and other wireless connected devices. The specification achieves these capabilities while keeping costs low and reducing power consumption to protect battery life.

“The success of any smartphone in the market today is highly dependent on camera functionality and image quality. Consumer expectations and demands for these features are increasing, which presents ongoing design challenges for vendors,” said Joel Huloux, chairman of the board of MIPI Alliance.

“MIPI Alliance, through its CSI specifications, plays an essential role in enabling camera applications in mobile and mobile-influenced devices. With the new MIPI CSI-2 v1.3 interface, companies can respond to customer demands.”

MIPI CSI-2 has achieved widespread adoption in the smartphone industry for its ease-of-use and ability to support a broad range of imaging solutions. The new release, v1.3, ensures compatibility to earlier versions of the specification so vendors can continue to use their existing product development infrastructure. The new interface also offers companies the opportunity to operate CSI-2 on either of two physical layer specifications from the MIPI Alliance: MIPI D-PHYSM, which CSI-2 has used traditionally, as well as MIPI C-PHYSM, a new PHY that MIPI Alliance released as v1.0 in September 2014. Products may implement CSI-2 solutions using either or both PHYs in the same design.


MIPI C-PHY uses 3-phase symbol encoding of about 2.28 bits per symbol to transmit data symbols on 3-wire lanes, or “trios,” with embedded clocking, facilitating longer trace reach and maximizing camera port configurations on mobile platforms. MIPI CSI-2 v1.3 with C-PHY provides performance gains, increased bandwidth delivery of 22.7 Gbps over four lanes at 2.5 Gsps (Giga-symbols per second) for realizing higher resolution, better color depth, and higher frame rates on image sensors while providing pin compatibility with MIPI D-PHY. Popular imaging formats including 4K video at 30 FPS (frames per second) using 12 BPP (bits per pixel) may be delivered using a single MIPI C-PHY lane.

Products implementing CSI-2 and D-PHY v1.2 can achieve a peak transmission rate of 2.5 Gbps over a single lane or 10 Gbps over four lanes. A 12 BPP, 30 FPS 4K video can be transmitted using two data lanes.

In addition to widespread use of CSI-2 in mobile devices, MIPI CSI-2 v1.3 performance capabilities are aligned well for the use of camera sensors in wireless lifestyle, wearable, surveillance, automotive and other applications. With the release of MIPI CSI-2 v1.3, manufacturers employing a camera serial interface can now select from the updated CSI-2 specification, or MIPI Alliance’s additional high-performing CSI specification, MIPI CSI-3SM v1.1, and apply the specification that best meets their needs, application, and choice of physical layer.

MIPI CSI-3 v1.1 uses the MIPI UniPort-M interface, composed of the MIPI M-PHY® physical layer and the MIPI UniPro transport layer, to support applications requiring high data rates, fast in-band control, device discovery capabilities, data transfer over networks, reliable delivery of data, and management of multiple data streams. It can service high-resolution and high-frame-rate sensors, digital still cameras, video recorders and camera arrays with a data signaling rate of 5.8 Gbps per lane.Products implementing CSI-3 v1.1 can transmit a 12 BPP, 30 FPS 4K video using a single data lane.

Companies employing either of the MIPI CSI specifications also gain the interoperability and cost benefits that standardized interfaces provide, such as the ability to source components from a wide variety of vendors, reduced development costs and the licensing benefits that membership in MIPI Alliance provides.

“We are very pleased, through the continued advancement of the MIPI CSI interfaces, to enable manufacturers to expand the capabilities and versatility of their designs and to extend the applicability of MIPI CSI into new markets. We look forward to continued work with stakeholders to identify and support new use cases and we invite companies in these important ecosystems to join us in this ongoing work,” said Bruno Trematore, chair of the MIPI Alliance Camera Working Group.


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