Phone Alliance’s Standard Targets Automotive Sensors

October 1, 2018

Terry Costlow

The MIPI Alliance is working to help automakers process the skyrocketing amount of data available to vehicles from a growing number of high-speed sensors. (Credit: MIPI Alliance)

Smart phones appear set to expand their burgeoning role in the automotive industry. The MIPI Alliance, which created interface standards for cameras and displays, plans to have a high-speed automotive standard ready by the end of 2019.

MIPI’s Automotive Working Group plans to complete the MIPI A-PHY, a physical layer specification that moves data from cameras, radar and lidar at 12-24 gigabits per second (Gbps). The group is also developing 48 Gbps technology for displays and other systems.

Timing for completion of the document means it won’t show up on new vehicles for a few years. Matt Ronning, MIPI Automotive Working Group Chairman, told SAE’s Autonomous Vehicle Engineering that this timeframe fits well with the industry’s need for very-high-bandwidth communication lines.

“The real demand comes with autonomous vehicles that will have from nine to 16 cameras, plus radar and lidar,” he said.

The MIPI spec will be complementary to the industry’s shift from CAN to Ethernet, which provides the band-width needed when several ADAS systems work together. The interface that’s used for most smartphone cameras provides high speed, but developers must overcome various hurdles, particularly in signal-line length.

“Gbit Ethernet is coming next year for cars, but in phones, MIPI is already providing 10 Gbits/second,” said Rick Wietfeldt, MIPI Alliance board member and former chair, MIPI Technical Steering Group. “Mobile is leaps and bounds ahead in speed, but they’re looking at lengths of 15 centimeters, while automotive needs 15 meters.”

Today, most automotive sensor systems use proprietary interfaces, noted Peter Lefkin, Managing Director of the MIPI Alliance. And some data links provide power, while others don’t. A faster standard will help developers meet the demands that will come when larger numbers of high-resolution sensors transmit data to centralized controllers.

“Cameras and radar are really driving the data rates now,” Lefkin explained. “Requirements are going up quickly. A lot of cameras today have 2 Mpixel resolutions; in the fairly near future, they will be going to 8 Mpixels.”

Along with the length of signal lines, automotive applications have more stringent functional-safety and electromagnetic-coupling requirements. Functional safety introduces overhead, which must be looked at the earliest stages of standard development, Wietfeldt said. Developers also are looking closely at crosstalk, which can be an issue when many high-speed lines are routed into electronic control units (ECUs).

Most automotive semiconductor suppliers are members of the Automotive Working Group, along with design tool providers and supplier Robert Bosch. Since the non-profit MIPI Alliance was founded in 2003 by ARM, Intel, Nokia, Samsung, STMicroelectronics and Texas Instruments, its membership has grown to more than 300 companies.