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.
The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
61–70 of 98 posts
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#62Some 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, eve…
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)
Yep, that must be it. Thanks!
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#63It 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…
They're using long-obsolete process nodes, so they can use surplus equipment, but at the cost of power efficiency. (Yes, that obsolete.)
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#64It 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…
They're using long-obsolete process nodes, so they can use surplus equipment, but at the cost of power efficiency. (Yes, that obsolete.)
Could mcu's made using modern processes be as cheap ?
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#65Earlier quoted context omitted.
Here's this experiment sort-of running: 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 pi…
> And since risc-v has versions somewhere around 5K-10K gates, well, a lower end mcu isn't far, probably. 5-10k? Seriously? That's amazing. Z80 had 8500. According to Wikipedia, even truly simple and bare bones 6502 had 3510 or 3218.
Designs like the GreenArrays F18A core show that you can do dramatically more than the 6502 or Z80 did in a similar number of transistors. The J1 and J1A are free descendants. The MOStek and Zilog hackers were wizards but they were working under serious time and, in the Zilog case, compatibility constraints. We know enough to do better now.
(https://news.ycombinator.com/item?id=20688443 is on the same topic.)
(As others commented, those are transistor counts.)
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#66> 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. If you're allergic to 555s, I guess?
The microcontrollers we're talking about here cost the same as a 555, or less, and don't need external timing components.
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#67Earlier quoted context omitted.
I'd guess about 1 MB order of magnitude. That would be a butt-load even for samples. 1 MB would be enough for 45 seconds audio at 8 bit PCM @22 kHz. If they're half competent, they could use ADPCM or much better (and cheaper to decode too!) vector quantization. With VQ, you could go even down to ~1 bits (~6 minutes of audio per megabyte) per sample while maintaining good audio quality. Decoding is very simple, so 650…
> [Vector quantization] Decoding is very simple. Do you have an encoder/decoder to point us to?
Arithmetic coded uniform quantization works very well and is straightforward to implement!
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#68Earlier quoted context omitted.
They're using long-obsolete process nodes, so they can use surplus equipment, but at the cost of power efficiency. (Yes, that obsolete.)
Could mcu's made using modern processes be as cheap ?
I don't know, but so far nobody has managed to do it. These microcontrollers aren't just cheaper than other microcontrollers. They're cheaper than most discrete transistors, cheaper than 555s, cheaper than shitty op-amps, cheaper than linear regulators, cheaper than many diodes.
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#69Some 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, eve…
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.
http://www.righto.com/2016/09/sonicare-toothbrush-teardown.h...
Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers
#70> 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. If you're allergic to 555s, I guess?
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.
True. This is still cool, tho: https://shop.evilmadscientist.com/tinykitlist/652