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Smart flash for smart cars: The benefits of NOR

NAND flash is the storage in your notebook, thumb drive, and camera. But NAND isn't the only kind of flash. For our self-driving car future though, the other flash - NOR - is a critical component. Here's why.

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If you're wondering why you've never heard of NOR flash, here's one reason: NAND flash is a $40B industry; NOR flash is a $2B niche. It also costs significantly more than NAND, so if designers can replace NOR with NAND, they do. But there is a steady and growing market for NOR.

NOR's big advantage is that it is a lot more rugged than NAND. And rugged is the name of the game in automotive, industrial, and - looking to the future - 5G wireless. I spoke to Sam Geha, EVP of the Cypress Semiconductor memory division, about the role of NOR flash in storage and their newly announced Semper flash memory.

NOR benefits

Semper NOR offers a basket of capabilities that make it attractive for critical use. Including:

  • 25 year data retention
  • 1 million+ writes
  • 11µA standby current
  • 1.2µA deep power down current
  • On board error detection and correction

That last item points to one of the unique features of the Semper NOR flash memory: it has a built-in ARM Cortex M0 CPU. That CPU also handles CRC for data and the interface, SafeBoot, memory sector protection, and diagnostics. Security? The ARM core is not user accessible. All you see is a standard serial NOR interface.

The Cortex also gives them a smarter way of handling wear leveling. The storage can be partitioned and configured for either 25 year data retention, or write endurance of over 1.25 million writes.

Automotive

One requirement of automobile cameras is "instant-on" performance. NOR's low read latencies means it can be used for direct code execution and data storage, critical for fast waking from sleep.

In addition, NOR offers the convenience of byte-level random access reads and writes, unlike the much longer and larger write cycles NAND flash requires. But the big difference is the spec. Semper NOR flash can handle 125C, a temperature where NAND flash rapidly loses endurance.

There's an ISO standard for the functional safety of electronic systems in automobiles: ISO 26262. It covers hardware, software, and system development, as well as production and operation, which Semper NOR flash is the first storage to meet.

The Storage Bits take

Embedded memory and storage doesn't get much attention, nor should it. It should just work.

But that doesn't mean there isn't real innovation going on under the covers. There is, and it pays dividends to all of us who rely on technology to live our lives.

Given that we have millions of driver-assisted and, soon, self-driving cars on the road, I like the idea of a comprehensive standard. And a storage technology that can reliably power systems that can kill if hacked or they fail.

Courteous comments welcome, of course.