A friend who frequently does contract development in the toy space has (or at least used to have) a favorite go-to MCU that costs under $0.06 in bare die. It is essentially a 6502 with 100 bytes of RAM and a metric butt-load of mask-programmable ROM. It was originally designed for greeting cards. He has designed it into toys.
It is hard to use, you need a dev kit and a good relationship with the distributor to get the documentation. It only makes sense in high-volume products, since it comes as passivated bare die so assembly requires a die-bonder and expoxy encapsulation depositer.
Not for everyday use. But as my friend says: “You haven’t lived until you have spent an entire afternoon arguing over $0.05 on the BOM.”
That sounds very similar to my experience with toy development. For a toy that played a bunch of pre-recorded sounds, we used a 4-bit Winbond MCU (their MCU division is now Nuvoton) that had a tiny bit of RAM and a ton of mask ROM. Firmware development was done in assembly and targeted a huge (physically large) emulator for test/debug. When we were satisfied with the firmware, we'd send it off to our CM, who would then order the parts with our FW in ROM. They'd get back bare die parts, which were wire bonded to the PCB and then epoxied over (that miserable "glop top" packaging, which is the bane of many teardowns). Development was a bit painful, but high volume production was extremely cheap.
Edit: Oops. I conflated projects. The toy project actually used a SunPlus MCU, not a Winbond MCU. It was an 8-bit RISC CPU running at 5MHz with 128 bytes RAM and 256KB mask ROM. The ROM held both the program and audio samples. I don't recall what encoding was used for the audio.
Great story, thanks for sharing. I for one pretty much constantly live the life he alludes to at my company bomquote.com. In China, we actually negotiate in increments of ~1/6th of a penny.
Ah, yes, there was an article here a year back about the original Furby using that same configuration. The article actually had the annotated 6502 source code.
Some Philips sonicare toothbrushes use(d) a 4-bit microcontroller from an obscure Swiss company. (From memory, since I can't find the EEVBlog video teardown) 52 bytes of RAM, custom size mask ROM, ? Kilohertz clock speed. It makes sense, they just needed a timer for the "2 minutes of brushing is up" feature, and maybe some battery management. It still surprised me that it was worth the hassle to save a few cents, even if they sell millions of the things. They must make insane margins: $80 for a vibration motor and $25 brush refills.
It's pretty easy to make the hassle worthwhile, if you are selling (particularly many) millions of things. Even saving a dime on BOM for a million units shipped will pay an engineer year, roughly.
I still remember a friend relating with a mixture of horror and fondness that in 15 years probably the biggest impact he ever had to the bottom line of [big computer manufacturer no longer in existence] was re-routing a PCB in a way that let them make it smaller with no functional change. The materials cost savings over product lifetime was in the 7-8 figures range, he claimed.
I did a teardown of a Sonicare toothbrush that used an 8-bit PIC 16F1516 microcontroller. There's a lot more going on in the toothbrush than I expected. I expected a simple motor, but there's a mechanically-complex resonant coil mechanism, driven by an H-bridge. There's some expensive manufacturing in there. Another interesting thing was the toothbrush has a "pressure sensor" to tell if you're brushing too hard, but it's really a Hall-effect sensor.
EM Microelectronics is actually not so obscure. They belong to the Swatch group and are specialized in ultra lower power analog and mixed signal circuit. Obviously, first for watches.
Are you thinking of this Braun teardown? https://www.youtube.com/watch?v=JJgKfTW53uo That indeed uses a 4-bit micro from a Swiss company (The only sonicare teardown I found was a forum post)
It is interesting that its possible to produce chips at this price for more than a short time period. Also that they are all basically PIC clones or variants speaks to the core competency of these companies is manufacturing and operational efficiency, not MCU design.
I think a fascinating experiment here would be to invest some time in an unencumbered scalable design that could be implemented very inexpensively (say less than 10K gates). Would these manufacturers pick up that design and run with it, making variants and parts that people could buy? It would get Microchip off their back (several have been sued apparently).
> I think a fascinating experiment here would be to invest some time in an unencumbered scalable design that could be implemented very inexpensively (say less than 10K gates). Would these manufacturers pick up that design and run with it,
I have done that thought experiment many times. I have a ISA that I sketched out many years ago but never did anything with. Often, I have thought it would be a real hoot to put up a working Verilog model on Github with a public domain license just to see if I could bait somebody in China into manufacturing it for me so that I could buy it off Digi-Key :)
Of course, the CPU isn't really the value any more. One salesman for an ARM licensee said it best: "Look at the die photos from any of the ARM licensee's. We are all just selling value-added flash." And as far as that goes, it isn't the CPU that drives the part design-in decision. It is having good, bug-free, peripherals in the right mix and a reasonable tool chain.
So the "free CPU design as wild oats" idea has appeal, but it would need an LLVM back-end to go with it, at minimum, and then unencumbered Verilog for a collection of basic peripherals.
And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably.
Still, it would be interesting to think how we can get from that, to standard peripherals, and standard pinouts, used by at least 2 mcu makers. That would be interesting.
I would think a lot of manufacturers are looking to RISC-V for that kind of eventuality. But in the meantime, and looking at that chart, it seems a lot more convenient to just rip off the PIC.
When getting into a project, I usually work with someone in the hardware design space (I can do larger electronics myself and thus prototypes, but I'm hired for very small circuit projects) and after creating a prototype, we usually start searching for the the cheapest MCU (and other components) that fit the project. Spending a lot of time doing assembly and making it fit the constrained memory will pay off when doing million factory runs. A lot of MCU's I work with are faster (or only marginally slower) than my beloved Z80 I grew up with an programmed many years, but usually have less (sometimes far less) memory. I have not worked with kilohertz since the early 80s but he, if it fits (it almost never does) I am all for the lowest priced and power friendly MCUs I can find.
It's funny but I've been driving a Z80 with an arduino-mega recently, and I actually timed it for the first time a couple of days ago. I'm getting 6000 clock-cycles a second. 6Khz, rather than that 6Mhz it would be cable of running standalone.
I wonder how much of Microchip revenue is from old chips at very profitable prices.
I did a Digikey comparison once, and Microchip alone provided roughly 30% of all MCUs on digikey. It has, for example, an incredible 175 MCU models with exactly 64B of RAM, 1.75KB of ROM and just 5 I/Os.
> They address a specific category of low-cost, high volume, non-serviceable products with limited functionality. You need to wait for the push of a button and then let an LED flash exactly five times? You need to control a battery-operated night light? The sub $0.10 MCU is your friend to reduce BOM and shorten development time.
These are cheaper than 555s, more easily available in various footprints, need almost no supporting passive circuity or glue logic, lower power usage, and more flexible to boot.
Popularity of the 555 waned a long, long time ago.
For the push button example I can envision using a pair of 555s or a 556 as a timer for the flashing and a latch to store the success condition, but how does it count to 5? You need more logic in here, so why not a cheap programmable chip?
You would be surprised by the places sub-$1 mcus appear, even down to a dime. Car manufactures use them all over the place, even ECUs(at least until recently; I'm no longer "in the biz"). Yes, shaving a few pennies from the BOM of a $30K device is still worth doing when you produce them in huge volume.
After I got over being spoiled by ARMs I fell for Padauk's stuff which I now think are awesome and makes almost everything that leaves the building a candidate for a micro. It breaks the old rules where you had to have a certain level of complexity in the product to justify using a processor. Their stuff are economical replacements for discrete logic and a no brainer for the ubiquitous ADC->serial use cases.
My hardware guy came on really heavy against the Padauk stuff because it was put to me that the temperature range wasn't wide enough particularly at the high end where supposedly we had to operate at 125C. I actually think attinys made it in the design instead of the Padauks just because of personal preference and an unwillingness to share the project rather than unavailability in automotive temp range.
So the tubes of Padauks and a pair of ICEs I brought in so it would be very easy to play with sit unused and I am now at a different place that places more emphasis on what all of the engineers think rather than just whoever happened to draw the long straw for the project.
dbcurtis|6 years ago
A friend who frequently does contract development in the toy space has (or at least used to have) a favorite go-to MCU that costs under $0.06 in bare die. It is essentially a 6502 with 100 bytes of RAM and a metric butt-load of mask-programmable ROM. It was originally designed for greeting cards. He has designed it into toys.
It is hard to use, you need a dev kit and a good relationship with the distributor to get the documentation. It only makes sense in high-volume products, since it comes as passivated bare die so assembly requires a die-bonder and expoxy encapsulation depositer.
Not for everyday use. But as my friend says: “You haven’t lived until you have spent an entire afternoon arguing over $0.05 on the BOM.”
jerryr|6 years ago
Edit: Oops. I conflated projects. The toy project actually used a SunPlus MCU, not a Winbond MCU. It was an 8-bit RISC CPU running at 5MHz with 128 bytes RAM and 256KB mask ROM. The ROM held both the program and audio samples. I don't recall what encoding was used for the audio.
bobjordan|6 years ago
andrehacker|6 years ago
https://news.ycombinator.com/item?id=17751599
MarcPereira|6 years ago
In Brazil, Holtek has a huge presence in that niche.
somesortofsystm|6 years ago
Without question, one of the nicest platforms to have in multitudes of thousands, at low energy and cost ..
nsxwolf|6 years ago
benj111|6 years ago
What would that be in this context? I'm guessing we're talking KB rather than TB?
tomcam|6 years ago
mastax|6 years ago
ska|6 years ago
I still remember a friend relating with a mixture of horror and fondness that in 15 years probably the biggest impact he ever had to the bottom line of [big computer manufacturer no longer in existence] was re-routing a PCB in a way that let them make it smaller with no functional change. The materials cost savings over product lifetime was in the 7-8 figures range, he claimed.
kens|6 years ago
http://www.righto.com/2016/09/sonicare-toothbrush-teardown.h...
kken|6 years ago
https://www.emmicroelectronic.com/catalog?title=&term_node_t...
EM Microelectronics is actually not so obscure. They belong to the Swatch group and are specialized in ultra lower power analog and mixed signal circuit. Obviously, first for watches.
fpgaminer|6 years ago
creddit|6 years ago
Scoundreller|6 years ago
And I buy the heads from Asia too for a fraction of the store price.
ChuckMcM|6 years ago
I think a fascinating experiment here would be to invest some time in an unencumbered scalable design that could be implemented very inexpensively (say less than 10K gates). Would these manufacturers pick up that design and run with it, making variants and parts that people could buy? It would get Microchip off their back (several have been sued apparently).
dbcurtis|6 years ago
I have done that thought experiment many times. I have a ISA that I sketched out many years ago but never did anything with. Often, I have thought it would be a real hoot to put up a working Verilog model on Github with a public domain license just to see if I could bait somebody in China into manufacturing it for me so that I could buy it off Digi-Key :)
Of course, the CPU isn't really the value any more. One salesman for an ARM licensee said it best: "Look at the die photos from any of the ARM licensee's. We are all just selling value-added flash." And as far as that goes, it isn't the CPU that drives the part design-in decision. It is having good, bug-free, peripherals in the right mix and a reasonable tool chain.
So the "free CPU design as wild oats" idea has appeal, but it would need an LLVM back-end to go with it, at minimum, and then unencumbered Verilog for a collection of basic peripherals.
petra|6 years ago
WCH, which sells cheap mcu's(like $0.25 8051-mcu with usb/16Kflash) is working on a risc-V bluetooth mcu:
https://www.cnx-software.com/2019/02/16/wch-ch572-risc-v-mcu...
And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably.
Still, it would be interesting to think how we can get from that, to standard peripherals, and standard pinouts, used by at least 2 mcu makers. That would be interesting.
nabla9|6 years ago
joezydeco|6 years ago
kragen|6 years ago
tluyben2|6 years ago
stevekemp|6 years ago
azinman2|6 years ago
the-dude|6 years ago
Today, Mouser lists 1 pcs @ € 0,908, 100 pcs @ € 0,863.
The guilder/€ is 2,20371 ( muscle memory ).
The MCUs in the article are 12C508A class, one is an actual clone.
So for ~ € 0,80 at quantity, the 12C508A currently costs about 1.75 guilder. 20 years later.
childintime|6 years ago
I did a Digikey comparison once, and Microchip alone provided roughly 30% of all MCUs on digikey. It has, for example, an incredible 175 MCU models with exactly 64B of RAM, 1.75KB of ROM and just 5 I/Os.
firethief|6 years ago
If you're allergic to 555s, I guess?
HeyLaughingBoy|6 years ago
throwaway2048|6 years ago
Popularity of the 555 waned a long, long time ago.
nsxwolf|6 years ago
kragen|6 years ago
Havoc|6 years ago
hmm. Well I don't blame the author but that kinda killed my interest
rtpg|6 years ago
gumby|6 years ago
dbuder|6 years ago
[deleted]
zokier|6 years ago
howard941|6 years ago
My hardware guy came on really heavy against the Padauk stuff because it was put to me that the temperature range wasn't wide enough particularly at the high end where supposedly we had to operate at 125C. I actually think attinys made it in the design instead of the Padauks just because of personal preference and an unwillingness to share the project rather than unavailability in automotive temp range.
So the tubes of Padauks and a pair of ICEs I brought in so it would be very easy to play with sit unused and I am now at a different place that places more emphasis on what all of the engineers think rather than just whoever happened to draw the long straw for the project.
unknown|6 years ago
[deleted]
kabdib|6 years ago
It was a fun little project: http://www.dadhacker.com/blog/?p=1911
kristianp|6 years ago