Memory // Storage

Automotive Black Box Memory Requirements

By Kristen Hopper - 2017-01-26

In December 2012, NHTSA proposed a rule requiring event data recorder (EDR) installation in all 2015 and later model passenger cars for recording important data including

  • airbag deployment
  • brake position
  • seat belt buckling
  • throttle position
  • vehicle speed

An EDR typically records data continuously, repeatedly writing over data until a vehicle experiences a collision, at which point the device stores up to 20 seconds of data from immediately prior, during and after the crash event.

Car manufacturers have already introduced these devices in new cars such that NHTSA issued a ruling in August 2006 requiring that automakers inform consumers of 2011 and later model vehicles whether EDR had been installed.

EDR technology, conceived to protect manufacturers against claims of a malfunctioning airbag causing injuries, was embedded in the airbag sensing and diagnostic module (SDM) that controls deployment. Captured data revealed pre-crash operator and vehicle behavior, facilitating deployment algorithm improvements and consequently further improving safety.  Through enhanced system development, these data can be further employed to improve mobility, productivity, traffic efficiency and environmental quality by predicting human error and anticipating, and thus avoiding/mitigating, potentially ensuing crashes.

Recently the U.S. government issued its first automated vehicle rules, which include a 15-point set of “safety assessment” guidelines for self-driving systems. These guidelines cover issues such as cybersecurity, black-box recordings to aid crash investigations, and potential ethical enigmas on the road. One of the principal challenges when designing such a self-driving system is to provide sufficiently reliable video storage media.

Various Automotive OEMs extend the EDR capability and include video recording functionality. That trend is driven by insurance companies in various countries which provide incentives to end customers that have an EDR with video recording capability in the car. Such a system captures video from up to four cameras originally intended for surround view; the cameras compress the video to h.264 or other format, generating continuous bit streams in the range of 1…12Mb/s for each camera.  A high-end system generates a total continuous data bandwidth of up to 6MB/s to be stored on a non-volatile memory (NVM) device.  A microcontroller uses various memory devices in automotive black box applications as follows:

  • receives the camera’s data streams and stores them in NVM media such as e.MMC, SSD or SD-card
  • utilizes an additional DRAM as a video buffer in order to compensate the NVM media storage’s write latency
  • uses e.MMC for code storage

Future high-resolution cameras will require much greater data bandwidth, difficult for today’s technology to manage.  NVM has a limited number of program/erase cycles such that selecting the appropriate solution requires application usage profile analysis with the various technologies under consideration.  New NVM technologies with improved write budget will be essential in future black boxes video recording applications.

Micron’s Automotive managed storage devices have been designed to address rather stringent requirements of today’s and tomorrow’s EDRs. For example, eMMC and SSD devices contain firmware which can format MLC (multi-level cell) memories as SLC (single level cell) memories - directly extending the Program / Erase cycles of the device for extreme applications where high reliability is a priority. Through the application of these types of innovations, even high endurance SD-cards can be employed in high reliability EDRs. Micron’s 20+ year commitment to the automotive market and expansive automotive qualified memory portfolio make Micron the perfect choice for your next automotive design.

Visit Micron’s Automotive Solutions page to learn more about our automotive memory and leadership in this area.

Kristen Hopper

Kristen Hopper

Kristen Hopper is Senior Manager, Managed NAND Design at Micron.  An IEEE Senior Member with >25 years’ global semiconductor industry experience, she received her M.S.E.E. from the University of California at Berkeley and B.S.E.E. with Distinction from Cornell University.