MIPI Alliance updates CSI spec for media rich mobile apps

The MIPI Alliance has just released its CSI-2 v1.3 update to its Camera Serial Interface (CSI) specification.

According to Joel Huloux, chairman of the board of MIPI Alliance, the new specification upgrade will make possible higher-resolution imaging capabilities, natural color representation and advanced video capabilities to smartphones and other wireless connected devices.

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

In addition to keeping costs of manufacture low and reducing power consumption, he said the V 1.3 release is designed to ensure compatibility to earlier versions of the specification .

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,” said Huloux. .

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, ” said Huloux, CSI-2 v1.3 performance capabilities are aligned well for the use of camera sensors in wireless lifestyle, wearable, surveillance, automotive and other applications.”

Designers of such devices, he said, 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.

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