It's Not All Linux
Posted by Jack Ganssle
In the comments section of my 2020 embedded salary survey, quite a few respondents felt that much of the embedded world is being subsumed by canned solutions. Will OSes like Linux and cheap, powerful boards like the Raspberry Pi and Arduino replace traditional engineering? Has that already happened?
A number of people complained their colleagues no longer understand low-level embedded things like DMA, chip selects, diddling I/O registers, and the like. They feel these platforms isolate the engineer from those details.
Part of me says yeah! That's sort of what we want. Reuse and abstraction means the developer can focus on the application rather than bringing up a proprietary board. Customers want solutions and don't care about implementation details. We see these abstractions working brilliantly when we buy a TCP/IP stack, often the better part of 100K lines of complex code. Who wants to craft those drivers?
Another part of me says "save me from these sorts of products." It is fun to design a board. To write the BSP and toss bits at peripheral registers. Many of us got a rush the first time we made an LED blink or a motor spin. I still find that fulfilling.
So what's the truth? Is the future all Linux and Pis?
The answer is a resounding "no." A search for "MCU" on Digi-Key gets 89,149 part numbers. Sure, many of these are dups with varying packages and the like, but that's still a ton of controllers.
Limiting that search to 8 bitters nets 30,574 parts. I've yet to see Linux run on a PIC or other tiny device.
Or filter to Cortex-M devices only. You still get 16,265 chips. None of those run Linux, Windows, BSD, or any other general-purpose OS. These are all designed into proprietary boards. Those engineers are working on the bare metal... and having a ton of fun.
The bigger the embedded world gets the more applications are found. Consider machine learning. That's for big iron, for Amazon Web Services, right? Well, partly. Eta Compute and other companies are moving ML to the edge with smallish MCUs running at low clock rates with limited memory. Power consumption rules, and 2 GB of RAM at 1 GHz just doesn't cut it when harvesting tiny amounts of energy.
Then there's cost. If you can reduce the cost of a product made in the millions by just a buck the business prospers. Who wants a ten dollar CPU when a $0.50 microcontroller will do?
Though I relish low-level engineering our job is to get products to market as efficiently as possible. Writing drivers for a timer is sort of silly when you realize that thousands of engineers using the same part are doing the same thing. Sure, semi vendors often deliver code to handle all of this, but in my experience most of that is either crap or uses the peripherals in the most limited ways. A few exceptions exist, such as Renesas's Synergy. They go so far as to guarantee that code. My fiddling with it leaves me impressed, though the learning curve is steep. But that sort of abstraction surely must be a part of this industry going forward. Just as we don't write protocol stacks and RTOSes any more, canned code will become more common.
Linux and canned boards have important roles in this business. But an awful lot of us will still work on proprietary systems.
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