STM8: a Hypothesis about Selling More for Less

A project log for eForth for cheap STM8S gadgets

Turn cheap stuff from AliExpress into interactive development kits!

ThomasThomas 12/01/2019 at 08:575 Comments

Yesterday I cleaned up the "STM8 low density devics" Wiki page. My initial target was to extend the scope from STM8S to STM8L devices, but I soon discovered that I had not had a clear understanding of the STM8S family variants when I had started that page.

This is no wonder at all, since the ST marketing has employees to invent funny categories like "Value Line", "Access Line" and "Performance Line" when they don't mean "value", "access", or "performance". A good example is the "Value Line" device STM8S007C8 high density (6KRAM, 64K Flash) performant (20 MIPS) µC which they sell at an accessible price. It's a safe bet that the device has 128K Flash and 2K EEPROM and that, as a hobbyist or "maker" you'll find that it operates reasonably well at 120°C.

While I was at it I had a closer look at the STM8S903K3, the "Application specific Line" device that's now quite cheap (around 30ct) and that I had earlier discovered to be the chip in the STM8S001J3M3, the STM8S in a SO8 package. At first sight there are two distinct chips in that line, the STM8S903 and the STM8SPLNB1, a DiSEqC slave chip. The datasheet gives it away as a STM8S903F3P6 chip that comes with an application for DiSEqC (i.e. program), and I assume that the NC pin18 is PD1/SWIM. If that's the case then case most of the function blocks in the datasheet's functional diagram are actually bit-banging software (i.e. there is only one HW I2C, namely SCL2).

I have to admire the boost of creativity, especially in the marketing department!

Overflows of creativity must have had an impact at other places, too, and if you're in the automotive market it's highly needed. Imagine you make a quote for an automotive micro-controller, e.g. a simple device for LIN slaves like the STM8AF6223: quantities are potentially huge but the environmental requirements are harsh (guarantee electrical parameters from -40 to 150°C operating temperature!), there is cut-throat competition, and the guys in the purchase department know their job!

Ah, yes, and there is catch: you must commit to delivering the same device for a long time, let's say 10 years. That, of course, only works if you can make money out of operating a fab for that long!

Also one should be able to "salvage" chips that have grades that are currently on short demand (e.g. chips that stay inside the specs from -40 to 85°C when there is only demand for, say, -40 to 125°C grade chips).

Now it's clear what's the job of the marketing department: find "less demanding" markets that can absorb what's otherwise surplus (if you can find a "more demanding" market that's of course also fine, provided you don't create *any* extra effort for the serious "automotive oriented" production process guys ;-) ).

That said, when I compared the STM8S903 and the STM8AF6223 datasheets I suddenly realized which kind of "application specific" requirements stands behind the luxury of producing two different STM8S low-density devices: the one from large automotive industry customers.

 I re-read the STM8S903 datasheet, and compared the configuration sections. The only real difference is that the UART is called "UART1" here and "UART4" or "LINUART" there. It's a safe bet that the STM8S001J3M3 can act as a standard compliant LIN2.2 slave, including baud-rate synchronization through -40 to +150°C without the need for a crystal. I'm sure that engineers in other markets will find a creative way to use such a nice feature.

Now the question is: why in the world does ST employ people who's job it is the make chips look like they're less capable than they are, why do they sell more for less?


de∫hipu wrote 12/01/2019 at 12:29 point

It's all about the market segmentation. If you sell things to different groups of people who don't communicate (or who you can prevent from communicating by introducing confusing nomenclature), then you can sell the same thing in each of the groups for the maximum price they are able to pay for it.

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Thomas wrote 12/01/2019 at 14:43 point

You have a point there - at least it's likely that some marketing managers actually *believe* in this kind of stuff. In the fact-minded world of technology such an approach can easily backfire. I mean there is only so much trust I can have in the veracity of a datasheet, right?

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Ken Yap wrote 12/01/2019 at 09:08 point

Payoff in bargains for the observant researcher. 👍 🙏

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Thomas wrote 12/01/2019 at 10:21 point

That's right. It's also interesting in one of my new as-lib areas of research: sociology of knowledge in socio-technical systems, e.g. "Resilience of Believe Systems through the Avoidance of Counter-Factual Reasoning in the Automotive Industry" ;-)

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Ken Yap wrote 12/01/2019 at 10:29 point


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