While at Intel I designed DRAMs and some researcher discovered that DRAMs were failing out in the field. These failures were being caused by Alpha particles in the ceramic packages that would strike the memory cell and change the charge in between refresh cycles, thus causing a one-time error. The solution was to literally coat the die with a material that would slow or deflect the Alpha particles and get ceramic packages that were more pure and contained less contamination.
Reading about the unintended acceleration issues faced by some Toyota car owners got me to thinking about a possible cause: Single Event Upset (SEU). We know that SEU becomes a higher probability as the node geometries shrink and circuits become more suceptible. This could explain why the acceleration issue only happens once in a while, and is elusive to create.
Maybe the EDA TCAD companies need to seize the opportunity and promote their SEU simulation tools more widely.
I did a little Google searching for keywords: SEU Toyota
and found the following discussions over at a forum on IEEE Spectrum:
Sung Chung 02.04.2010
I agree with William Price for Toyota’s SUA problems. I’ve been mitigating ground level radiation related SEU (Single Event Upset) issues for many years. Drive-by-wire control system for cars were well researched and SEU tested; SEU mitigation research results are starting to emerge. Safety related functions such as drive-by-wire throttle, brakes, or stability control are all part of SEU study as vehicle electronic technology becomes more complex. For engine control unit (i.e., CPU) manufactured using 65nm or below technology, logic primitive (Flip-flop and primitive gates) SER (soft error rate) starts to exceed that of SRAM memory cells for the same technology node. Without ECC ( Error Correction Code) or proper mitigation techniques, if ECU logic or memory containing the execution code is affected by SEU, the vehicle will exhibit unintended operation. How do we know Toyota has SEU related problems than all current fixes offered in the program? Good question and it’s relatively easy to prove, but it’ll be quite an intense and complex one: perform a accelerated neutron test on the key components and do a statistical analysis using data collected during the radiation test such as acceleration rate, failure rate, number of cars on the road, ground neutron fluence, geomagnetic rigidity etc. The test data will give statistical failure rate of SUA for the different altitude and geographical location. The reason why there are so much speculation in the SUA is it’s a CND (can not duplicate) in nature. The nature of the failure is a “soft error” rather than a “hard error.” It seems SUA failure mechanisms are “soft errors.” Try to find the hard evidence to find the solutions for “soft errors” will be a wrong approach. If the design did not incorporate SEU tolerant architectures including micro codes, it is worth pursuing SEU test since many lives are in the line and the current solutions may not solve root cause of the problem. Contact me for further discussion if interested at firstname.lastname@example.org.
William Price, Life Member IEEE02.02.2010
I am a physicist, retired after 20 years working at the Jet Propulsion Laboratory and other research labs before that. I have been following the Los Angeles Times articles about the sudden acceleration problems in Toyota and other vehicles. As a recent article has stated, a number of people are thinking that the problem is in the electronics. I do too. However the NHTSA officials have ‘found no evidence that any electronics defect exists in the company’s electronic throttle system.’ The problem, I believe, is that they are not looking for the right cause. I believe that the cause may be a phenomenon known in the aerospace world as ‘Single Event Upset’(SEU). The effect occurs when a single ionizing particle (cosmic ray) impinges on a sensitive part on an integrated semiconductor circuit causing the circuit to trigger some key unintended function. This effect is well known in the aerospace world and been studied for about twenty-five years. High-speed memory circuits are particularly sensitive. In such circuits the effect of an impinging ionizing particle can cause a 1 to become a 0 or visa versa. Other electronic device types are also sensitive to SEU. It has already been proved experimentally that such events can occur on earth’s surface. Solutions to the Aerospace SEU problems have been studied for years and several work-a-rounds exist. I would like the opportunity to talk to someone in the Toyota Company about this problem I need to talk to someone in engineering that is in charge of the electronics controlling the throttle. I can arrange for testing of their circuits using ionizing particles generated in particle accelerators. I can also arrange for experts on radiation environments to assess the probability of upset once the cross section for the effect has been experimentally determined. This testing would have to be done with the circuit engineer in charge of operating the electronics while the circuit is bathed in the particle field. My experience in radiation effects on materials, electronic parts and electronic systems goes back 45 years. I am one of the pioneers in the field. I was a leader of one of the two teams that originally proved that Single Event Upset does occur due to charged particles in Integrated Circuit Memory Devices used on spacecraft. I would appreciate any help you could give in making the right contacts to pursue this possible solution to the problem. William E. Price (Bill) Cell Phone: 760-666-0151 Email: email@example.com