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The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

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Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#91

Post by nickpsecurity »

kragen wrote: post #89
nickpsecurity wrote: post #76

Earlier quoted context omitted.

The other issue is that the older nodes are more reliable. They're already matured where they understand how to make everything work right. On top of that, each process shrink introduces new challenges that can cause components to fail. The most modern nodes seem like they make everything somewhat broken coming out the door with designers building in mitigations for that. They don't last as long. The older nodes don'…

I think Padauk is using 1.3-micron or something? Can't find my notes. I don't think you have to go quite that far into the stone age to get reliability, at least not for digital. Do you have funding to do a MOSIS run or two? I wonder if we could find some.

No funding at the moment: researching on the side while working a main job. The older nodes for MOSIS were 350nm and 500nm. The fabs for these penny chips can be stone age in comparison. You're right that you don't need to go that far given the highly-reliable POWER's and Alpha's weren't built on stone-age nodes. Edit to add that, based on MHz I remember, the Alpha's were 350nm-500nm. Fits MOSIS well. :)

If you do a project, I suggest 350nm since it's the last node that you can visually inspect the resulting silicon. It's as fast as you go before you need electron microscopes and such. It's also more likely that the open tools for hardware will be able to handle such a node instead of deep sub-micron. Finally, there's old research in transistor-level optimization that might be applied to it in new, open tooling. Might let people do standard cell that inches a bit closer to performance and energy use of custom designs.

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#92

Post by seanmcdirmid »

Scoundreller wrote: post #88
seanmcdirmid wrote: post #80

Earlier quoted context omitted.

The heads aren’t Phillips, just clones right? I would expect the brush you are buying to be a clone also, or at best a good knock off. Phillips is pretty disciplined about their pricing internationally. I buy cloned heads (but not the main brushes) and find them completely adequate.

The base was legit (or a 3rd shift kinda thing?), but the heads are definitely generics. Agreed, they work fine.

I’m very doubtful they were legit, anything labeled third shifts are almost always fakes. I can’t find any soniccare on alibaba (just a lot of clones), they have stuff on TMall, but all the prices are normal.

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#93

Post by Zardoz84 »

vardump wrote: post #38
benj111 wrote: post #20

Earlier quoted context omitted.

"metric butt-load of mask-programmable ROM" What would that be in this context? I'm guessing we're talking KB rather than TB?

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…

Using the trivial BTc encoding, you could archive a good compression ratio and generate audio without using a DAC . https://www.romanblack.com/picsound.htm

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#94

Post by kristianp »

stevekemp wrote: post #16
tluyben2 wrote: post #11

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 doin…

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.

Why is it so slow?

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#96

Post by marshray »

vardump wrote: post #53
tasty_freeze wrote: post #52

Earlier quoted context omitted.

The Z80 had that many transistors, not gates The CMOS rule of thumb is one gate is 4 transistors (eg a 2-input NAND). But the first Z80 was nmos, and so the equivalent count is harder to state. 3 transistors per 2 input nmos gate is a rough first order guess, but in nmos wide gates still need only a single load resistor, and designers sometimes used dynamic logic to save even more transistors.

Ohh... This is embarrassing! I work in embedded/low level and I have always thought that gate == transistor. It's really obvious in retrospect... I stand corrected.

It's not a crazy idea, there are indeed logic types that implement some gate types with a single transistor. For example, https://en.wikipedia.org/wiki/Resistor–transistor_logic

These were more commonly used back when transistors were expensive.

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#97

Post by pkaye »

sitkack wrote: post #55
pkaye wrote: post #25

Earlier quoted context omitted.

A product I was working on had different variants based on what parts are populated. There were config resistors to help route the signals based on what was populated. I replaced that all with a simple software lookup table in firmware to reroute the signals correctly. Furthermore I figured out how to auto-detect the dozens of supported configurations on first bootup. The PCBs were very small so I made the board desi…

I would hire you. These techniques should be applied pervasively. Could you write a guide? I would buy it.

Thanks for the kind praises. Unfortunately I'm not much of a writer though I have lots of interesting experiences that I tell my friends and coworkers.

A big part of how I'm today is due to my boss at that time. One of the most brilliant engineers I worked it. He also gave us a lot of time and freedom to think of these kind of approaches. Sadly these days a lot of companies are always in a rush so one can't think things through properly.

Re: The “terrible” 3 cent MCU – a short survey of sub $0.10 microcontrollers

#98

Post by stevekemp »

kristianp wrote: post #94
stevekemp wrote: post #16

Earlier quoted context omitted.

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.

Why is it so slow?

Mostly because I'm doing a lot of manual work reading/writing to the address/data-bus and there is some overhead in the code I've got for emulating RAM & I/O code.

It should be faster, and could be if I reworked it. But I'm mostly using the arduino as a crutch right now until I get hooked up to real driving circuitry so I'm not overly concerned.

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