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How bad can a $2.97 ADC be?

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Re: How bad can a $2.97 ADC be?

#101

Post by cycomanic »

londons_explore wrote: post #81
cycomanic wrote: post #53

Earlier quoted context omitted.

You can buy ADCs at over 100 GS/s (keysight, teledyne and tektronix make oscilloscopes using them), however typical ENOBs are more around 5 bits for these. For people interested in this stuff, I there is a video of someone taking apart one of the high speed keysight scopes (I think signal path is the YouTube channel?).

An oscilloscope is IMO just a user interface for an ADC. The adc is where the hard engineering lies, and the bit which should command 90% of the cost. Unfortunately this isn't the case - the company designing the plastic case and buttons gets the lions share of the money.

That's a weird argument. System integration is a significant amount of work. To get any data in and out of these high speed dac/ADCs requires significant man hours (several months to years) of rf, system, fpga and systems engineers. These scopes typically have some pretty hefty fpgas in them as well. All That comes at a significant cost (and those ADCs are not cheap either).

It's sort of like saying CPUs are the were all the hard work for computers is, so they should get all the money (not the motherboards, GPU and especially not software). That's just not how the economics of these things go.

Re: How bad can a $2.97 ADC be?

#102

Post by mrheosuper »

NoiseBert69 wrote: post #58
chillingeffect wrote: post #31

Earlier quoted context omitted.

If hate the esp32 adc, let me introduce you to its "fpu." Or its external flash and memory...

But no real competition for on-chip Wifi/BLE around. Only ugly two-chip solutions or hyper exotic stuff with no community.

oh there are a lots, it's just that they are not interested in Western market.

BES, Sifli, realtek, boufallo, etc.

Re: How bad can a $2.97 ADC be?

#103

Post by mastax »

MountDoom wrote: post #15

> These are cheap, relatively fast, and not particularly good. While they sport impressive-sounding 12- and 16-bit readouts, the effective number of bits (ENOB) is usually around 8 or 9. I don't think that's quite accurate for reasonably modern MCUs. You can typically shake 10+ bits out of them, but you need to take a lot of precautions, such as providing very stable external reference voltage and shutting down unnee…

I was planning on using (genuine) ADS1115s for a project but ended up going with an STM32g071 instead. It was cheaper, easier to source at the time (surprisingly) and much more flexible. The newer STM32g/h series ADCs have fewer hardware/software footguns than the old f103 et al.

Re: How bad can a $2.97 ADC be?

#105

Post by kragen »

q3k wrote: post #43
Hasz wrote: post #42

Earlier quoted context omitted.

I have done this a bunch of different times, mostly to resolve sourcing disputes. Dissolving in boiling sulphuric acid/nitric acid will make quick work of most epoxy packaging IMO, I have mostly seen mislabeling, rebinning, and passing off obvious QC rejects. example from many years ago: https://www.youtube.com/watch?v=e6DfBuPwAAA

> Dissolving in boiling sulphuric acid/nitric acid will make quick work of most epoxy packaging That's the better method of course (results wise), but it's not nearly as accessible, hence my recent evangelism of the virtues of 2000 grit sandpaper.

I've heard that boiling epoxy in molten colophony for a few hours, like a long-cooked version of rosin potatoes, will also dissolve it. I haven't tried it myself. Colophony is much more expensive than sulfuric or nitric acid, but safer to handle (when not molten) and often easier to get.

Re: How bad can a $2.97 ADC be?

#106

Post by kragen »

mastax wrote: post #103
MountDoom wrote: post #15

> These are cheap, relatively fast, and not particularly good. While they sport impressive-sounding 12- and 16-bit readouts, the effective number of bits (ENOB) is usually around 8 or 9. I don't think that's quite accurate for reasonably modern MCUs. You can typically shake 10+ bits out of them, but you need to take a lot of precautions, such as providing very stable external reference voltage and shutting down unnee…

I was planning on using (genuine) ADS1115s for a project but ended up going with an STM32g071 instead. It was cheaper, easier to source at the time (surprisingly) and much more flexible. The newer STM32g/h series ADCs have fewer hardware/software footguns than the old f103 et al.

What are the worst footguns on the STM32F103/GD32F103/CH32F103 ADC?

Re: How bad can a $2.97 ADC be?

#107

Post by kragen »

gsmecher wrote: post #37
throwup238 wrote: post #30

Earlier quoted context omitted.

Ah oops I missed that. Maybe an ADX111A then?

Oh my - good find, and also, eek. Analogy: https://datasheet.lcsc.com/lcsc/2302211830_analogysemi-ADX11... TI: https://www.ti.com/lit/ds/symlink/ads1115.pdf Analogy's datasheet is directly cribbed from TI's (see TI Fig. 7-7 / Analogy Fig. 22½, pg. 18). This already passes my "run away screaming" threshold for trust, but a decapping would help me understand whether they've stolen the physical design (bad) or just clon…

"Stealing" the physical design is legal after 10 years in the US (https://en.wikipedia.org/wiki/Integrated_circuit_layout_desi...), or 20 years if there's a patent, and that's how we avoided having a single giant company own everything and halt innovation forever in the First and Second Industrial Revolutions. So I would say that stealing the physical design is good.

Re: How bad can a $2.97 ADC be?

#108

Post by kragen »

londons_explore wrote: post #81
cycomanic wrote: post #53

Earlier quoted context omitted.

You can buy ADCs at over 100 GS/s (keysight, teledyne and tektronix make oscilloscopes using them), however typical ENOBs are more around 5 bits for these. For people interested in this stuff, I there is a video of someone taking apart one of the high speed keysight scopes (I think signal path is the YouTube channel?).

An oscilloscope is IMO just a user interface for an ADC. The adc is where the hard engineering lies, and the bit which should command 90% of the cost. Unfortunately this isn't the case - the company designing the plastic case and buttons gets the lions share of the money.

Analog signal integrity isn't trivial either, but it isn't the same kind of hard engineering as the ADC and as the amplifier chips in front of it.

Re: How bad can a $2.97 ADC be?

#109

Post by kragen »

squarefoot wrote: post #45
the__alchemist wrote: post #32

Earlier quoted context omitted.

H7s for <$1? I get confused whenever people talk about paying $0.69 for an MCU!

I recalled a few years ago there were shockingly inexpensive MCUs at LCSC and similar far east vendors, but they were never heard before names, so I just checked again out of curiosity and here's a $0.05 one by Cypress. https://www.lcsc.com/product-detail/C2954567.html

That's out of stock, though. Here are my other shockingly inexpensive MCUs at LCSC that were in stock at the time:

links from 02025-03-16:

https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU... #LCSC #pricing for 16-pin #CH32V003 #microcontrollers #electronics #hardware: 14.21¢ in quantity 500. Not the cheapest, but it’s a RISC-V with IIRC an on-board op-amp, though the linked datasheet only covers the CPU really.

https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU... #LCSC #pricing for 14-pin #PY32 #ARM #microcontrollers #hardware, 9.01¢ in quantity 500. Not the cheapest, but it’s an ARM. #electronics

links from 02025-02-08:

https://www.lcsc.com/datasheet/lcsc_datasheet_2410121502_PAD... #PDF English #datasheet for #Padauk PFS122 #microcontrollers which have a 12-bit ADC and 24MHz. Not quite the cheapest microcontroller but they only cost 4.32¢ in quantity 2000.

links from 02024-08-01:

https://www.lcsc.com/product-detail/Microcontrollers-MCU-MPU... new cheapest #microcontrollers: Cypress CY8C4045FNI-DS400T, 1.5¢ in quantity 1000. It purports to be a 48MHz Cortex-M0 ARM with 32KiB of Flash and 4KiB of SRAM in a 1.6mm x 2mm package, 0.31-0.37 mm thick, with nine GPIO pins. I think that’s 4000 Dhrystone MIPS per dollar. #electronics #hardware #pricing

links from 02024-05-12:

https://jlcpcb.com/partdetail/NyquestTech-NY8A051H/C5143390 #JLCPCB has new cheapest #microcontrollers: #Nyquest NY8A051H: 1.58¢ each in quantity 20000, or 3.2¢ in quantity 1 #hardware #pricing

links from 02023-10-12:

https://www.lcsc.com/product-detail/Microcontroller-Units-MC... #Padauk PMC251 is one of their cheapest multithreaded parts; LCSC lists it here at US$0.1071 in quantity 500, which works out to US$53.55. 1 kiloword instruction memory

As of today (02025-10-15), the CH32V003A4M6, the PY32F002BD15S6TU, the PFS122, and the PMC251-S14 are in stock. The CY8C4045FNI-DS400T, the CY8C4013SXI-400, and the NY8A051H (not an 8051 despite the name) are out of stock. Today what I see are:

https://www.lcsc.com/product-detail/C49173938.html Currently cheapest #microcontrollers #pricing on LCSC: PMS150G-U06 (a SOT-23-6) for 2.02¢ in quantity 3000. #Padauk has broken the 3¢ barrier! One-time programmable. #electronics #hardware

https://www.lcsc.com/product-detail/C2857167.html Almost cheapest #microcontrollers #pricing on LCSC: NY8A054ES8, a SOP-8, for 3.91¢ in quantity 1000. This is from JSMSEMI (Shenzhen JSMicro Semiconductor Co., Ltd.) 1T 8-bit 8MHz chip, 128 bytes RAM, 2k × 14-bit EPROM program memory (but no quartz window, so one-time programmable). 8-level hardware stack. The datasheet is full of descriptions of peripheral registers and pin circuit schematics, and then the 55-instruction instruction set is documented on pp. 76–91.

Re: How bad can a $2.97 ADC be?

#110

Post by alwa »

kragen wrote: post #105
q3k wrote: post #43

Earlier quoted context omitted.

> Dissolving in boiling sulphuric acid/nitric acid will make quick work of most epoxy packaging That's the better method of course (results wise), but it's not nearly as accessible, hence my recent evangelism of the virtues of 2000 grit sandpaper.

I've heard that boiling epoxy in molten colophony for a few hours, like a long-cooked version of rosin potatoes, will also dissolve it. I haven't tried it myself. Colophony is much more expensive than sulfuric or nitric acid, but safer to handle (when not molten) and often easier to get.

I did not know that. Pine rosin is such lovely and versatile stuff. And sure enough:

https://m.youtube.com/watch?v=pIpxawdUb4I&t=30m18s

…plus it smells much better; and, as you mention, it’s useful for potatoes too!

https://bittersoutherner.com/feature/2022/the-elusive-roots-...

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