Executive Editor
The MIPI Alliance sees its mission as establishing specifications for hardware and software interfaces in mobile devices as well as for applications that don’t necessarily fall within the mobile ecosystem. The organization has kicked off 2017 with two initiatives—the MIPI I3C sensor-interface specification and the MIPI Discovery and Configuration (MIPI DisCo) portfolio.
The latter is a family of specifications that simplifies software driver development when integrating components in mobile-connected products. MIPI Alliance members as well as members of the open-source community who don’t belong to the MIPI Alliance can access the MIPI DisCo specifications here: http://bit.ly/2iZFI8c. The goal is to encourage widespread adoption of the specifications and motivate the community to share its software development resources.
The MIPI DisCo architecture is based on the Advanced Configuration and Power Interface, which is used in the PC industry to manage their power states and is supported by all major operating systems.
The first interconnect-specific specification, MIPI Discovery and Configuration for SoundWire (MIPI DisCo for SoundWire), is scheduled for release later this year and will streamline software integration of amplifiers, microphones, and audio codecs that are built into smartphones, tablets, mobile PCs, connected cars, and IoT devices that use the MIPI SoundWire interface.
“The MIPI DisCo for SoundWire specification will help minimize the amount of device-specific code required for support in operating systems such as Microsoft Windows and Linux/Android,” said Pierre-Louis Bossart, chair of the MIPI Alliance Low-Speed Multipoint Link Working Group, in a press release. “It also provides platform-level information on the bus topology and lets the system integrator customize the SoundWire subsystem without changing the operating system and drivers.”
The MIPI I3C specification’s origins extend back to 2013, when the MIPI Alliance formed the Sensor Working Group with a goal to develop an I²C-compatible interface with sensor-focused, differentiated features. The specification gets its name from “Improved Inter-Integrated Circuit” and is intended to streamline sensor integration in smartphones, wearables, IoT devices, and automotive systems. The two-wire I3C is backward-compatible with I2C; legacy I2C devices can coexist with I3C devices in most cases.
In a recent phone interview, Ken Foust, chair of the MIPI Alliance Sensor Working Group, described I3C as a convenient chip-to-chip interface that alleviates the challenges of integrating sensors in product designs—especially for IoT, mobile, and automotive applications.
Foust said the development of the specification was spurred on by MIPI Alliance participants and members of the MEMS & Sensors Industry Group contending with shortcomings of the I2C and SPI legacy low-speed interfaces. For example, with I3C, he said, designers needn’t rely on GPIO for sensor-interface tasks.
He added that especially in the consumer space sensor technology is constantly changing, with embedded FIFO buffers in sensors accumulating data that must be transferred in bursts to the host processor. That, he said, can take a long time with a typical I2C bus operating at 400 kHz. In contrast, I3C offers a 12.5-MHz clock rate. SPI can handle the higher speeds, but it’s a four-wire interface that lacks features like in-band addressing and peer-to-peer communications.
Foust added that the collaborative effort that produced the MIPI I3C specification is ongoing, with work continuing to advance the specification to help companies meet the challenges of always evolving markets for sensor-enriched products.
Of course, I3C-based designs will need to be tested. Test is extremely important, Foust said, adding that instrument makers had participated in a MIPI developers’ conference. He expressed confidence that they will be onboard as MIPI I3C-based products emerge.