Mobile industry momentum around a new Chip-to-Chip Link, referred to as "C2C", was seen yesterday when Arteris announced that 10 system-on-chip (SoC) vendors have licensed the technology for application processors and modems.  C2C is an exciting new interface jointly developed by TI and Arteris to efficiently connect chips that can share memory and resources, providing significant benefits and enabling future innovations.  I wanted to blog about it because it can have significant implications, is generating strong industry interest.

"Best of Two Worlds"

The motivation for the C2C interface was to provide an efficient and seamless interface between mobile applications processors and modems that also provides significant cost and printed circuit board (PCB) area reduction.  With the high-bandwidth and low-latency C2C interface, the modem DRAM can be removed to save $2 and 115 mm2 in board space.  Even more importantly, this split architecture brings together the "best of two worlds" to provide the mobile industry's most optimal environment for innovation.   In the end, OEMs and ecosystem partners benefit from the growth of a cost-effective, thin-modem market and the opportunity to combine those modems with a best-in-class OMAPTM applications processor while saving cost and footprint at the same time.   This approach allows OEMs to maximize their investment in providing the best user experience, with the ability to select from multiple modems to meet different product and market requirements.   For example, a mobile device can be designed with a TI OMAP 4 applications processor with cost-effective variants that leverage best-in-class LTE, TD-SCDMA or WiMAX modems from different vendors to maximize the worldwide market opportunity.   Ultimately, OEMs and customers get better products with more choice.

While some industry pundits suggest integrated modem and applications processors will dominate future mobile markets, the reception of this news indicates that the industry is, in fact, behind discrete architectures-- the strategy behind TI's OMAP platform.

Opportunities "Beyond" Modem Integration

There are exciting opportunities to leverage the C2C interface beyond modem integration, as the interface provides memory-mapped transfers to support seamless system expansion.  Use of the C2C interface can expand the life and use of an applications processor by extending capabilities and adding new interfaces.  I can envision future companion devices such as FPGAs, coprocessors and interface bridges leveraging the C2C interface, opening up new opportunities for the industry.   The use of this interface for system expansion will extend the ability for applications processors to cost-effectively address new markets that demand unique interfaces without expensive re-design of the SoC.  

Some may say that they can do this today with other interfaces like USB or PCI Express, but there several significant advantages of the C2C approach.   The C2C interface logic is small and simple, has low latency (100 ns) and high bandwidth (800 MB/s) and does not require a PHY (allowing it to be multiplexed on the same pins as DDR memory if desired).   A very key differentiator for C2C is that it is also software-transparent since it is transporting memory transactions and does not use a software protocol stack.  It only requires one-time software initialization.   A benefit of this approach is that if the functionality is later integrated back into the SoC, it inherently has software compatibility.  All of these benefits uniquely position the C2C interface to enable future innovations.

Future Evolution

Seeing the great benefits and applications of the C2C interface, I thought it had a lot of potential with formal industry standardization to enable widespread usage.  In 2009, I proposed a new interface to the MIPI Alliance organization that defines and promotes interface specifications for mobile devices.   The MIPI Alliance embraced the concept and has developed the Low Latency Interface (LLI) based on the increasingly, popular M-PHY physical layer also used for future mass storage (JEDEC UFS) and chip-to-chip USB 3.0 (SSIC) interfaces.    A common PHY interface will lead to future cost and pin count savings and enable reuse of the same pins for different applications.  

C2C was intended for a few strategic partners, but after demand from others, we worked with Arteris to offer licensing to other companies, resulting in the success seen in yesterday's Arteris announcement.   The benefits and opportunities provided by C2C will extend far into the future along with LLI.

Leveraging C2C and LLI with TI OMAP Processors

The OMAP 4 platform supports the C2C interface today to enable efficient system expansion and modem integration.   The upcoming OMAP 5 platform supports both C2C and LLI interfaces for maximum compatibility and future applications.   TI is working with several modem vendors to offer efficient system solutions that take advantage of these interfaces to benefit OEMs and customers with the best user experiences provided by the OMAP platform coupled with the best selection of world-class modem solutions. 

As industry interest in the C2C and LLI interfaces expand, we look forward to seeing new products leverage the technologies to open up new opportunities for the industry.