[HN Gopher] How bad can a $2.97 ADC be?
___________________________________________________________________
How bad can a $2.97 ADC be?
Author : jamesbowman
Score : 158 points
Date : 2025-10-14 17:12 UTC (5 hours ago)
(HTM) web link (excamera.substack.com)
(TXT) w3m dump (excamera.substack.com)
| q3k wrote:
| Should be easy to compare - sand down both the cheapo and a legit
| one (with a similar datecode) with fine sandpaper, clean with
| isoprop and shove under an optical microscope - you can then tell
| how similar/dissimilar the dies are, you don't even have to look
| for markings or anything super legible, or even sand them to the
| same metal layer.
|
| Clones tend to be vastly different - different technology node,
| architecture, die size, etc. - that's because they are generally
| functional clones, not mask clones.
|
| (also, as a general shoutout to the low tech sandpaper technique
| for exploratory work, here's a sanded down RP2350 thrown under a
| clapped out SEM: https://object.ceph-
| eu.hswaw.net/q3k-personal/484e7b33dbdbd9... https://object.ceph-
| eu.hswaw.net/q3k-personal/3290eef9b6b9ad... )
| cheschire wrote:
| It may not even be a clone. As the author said, it could just
| as easily be production line items that were tested and found
| to be outside of spec tolerances and resold off-label.
| q3k wrote:
| Well, that's the point of the experiment, to figure out if
| it's a clone or a reject :).
| throwup238 wrote:
| TI makes all their analog stuff in house so that's unlikely.
| That's far more common for fabless companies that send their
| parts off to an outside fab.
| cheschire wrote:
| What does TI do with their out-of-tolerance products?
| Straight in the garbage?
| throwup238 wrote:
| Yes, though depending on the product line it may be
| binned into lower quality parts first. Remember though,
| the marginal cost of these chips is so small the
| packaging is usually more expensive than the silicon.
| They often get tested before the wafer is even sliced up
| so any waste is hardly worth mentioning until you get
| into modern processes with large error rates and huge
| chips like CPUs.
| 15155 wrote:
| TI isn't patterning $10000 wafers at 3nm with massive
| chiplets and questionable yield, they are making mostly
| commodity ICs on cheaper processes - they can afford to
| discard rejects.
| Lerc wrote:
| I think the implied question is do they discard, or do
| they destroy.
|
| Discarded things tend to get lost. Lost things tend not
| stay in the Anduin forever.
| LeifCarrotson wrote:
| > "Discarded things tend to get lost. Lost things tend
| not to stay in the Anduin forever."
|
| I'll have to put that on a warning label near our non-
| conforming-product containment shelf!
| pinkmuffinere wrote:
| Lol I love the deep cut to LOTR! Took me a sec but then
| brought me so much joy. Viva la nerds!
| Arubis wrote:
| Binned wafers are viable source material for
| photovoltaics.
| Hasz wrote:
| 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
| q3k wrote:
| > 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.
| jacquesm wrote:
| I like it. I've used sandpaper to solve some interesting
| problems in the past as well with great success. I suspect
| we are only seeing the beginnings here in a trend of high-
| tech applications of fine grit paper.
| Terr_ wrote:
| I expect it's _much_ easier to acquire fine sandpaper,
| yet my inner child yearns for laser decapping. (Or I
| suppose more than "decapping", depending on the depth.)
| jacquesm wrote:
| High power lasers are becoming more and more affordable.
| Laser ablation is definitely an option but you really
| want to have some proper fume extraction around that.
| BertoldVdb wrote:
| Laser decapping will destroy the die, except if you have
| a rare package that does not mix glass in the epoxy.
|
| You could still compare the internal structure of the
| package and bonding, but the die itself is mostly
| destroyed.
| supportengineer wrote:
| I'm off to build an MCP so AI can control the sandpaper
| jacquesm wrote:
| You may as well start off with one of these then:
|
| https://phillipscorp.com/india/phillipsgrinding/phillips-
| sur...
|
| All you need is a serial port and some G-codes.
| throwup238 wrote:
| I prefer Japanese sharpening stones or those DMT diamond
| whetstones. It's relative easy to 3d print a jig that
| converts a woodworking honing guide into an IC holder and
| you get a feel for how many passes to do very quickly
| before slowing down and checking each pass.
| Tade0 wrote:
| There was a sandpaper expert in that company associated
| with sour-tasting fruit which shall not be named. I believe
| you guys have met, though I think by that time he already
| pivoted to making the perfect cheesecake.
| hinkley wrote:
| <NileRed voice> ...I wanted to look at this chip... so first
| I put it in a jar of hot nitric acid.
| fullstop wrote:
| I don't know if we can ping people here, but this looks like
| something that would be right up Ken Shirriff's alley.
|
| 1. https://righto.com
| kens wrote:
| I have enough projects already, so I'm staying quiet here :-)
| fullstop wrote:
| I won't tell if you won't tell.
| mindslight wrote:
| Err, the title isn't really correct. The genuine part is still
| only $4. This is a 60 cent knockoff. Not having done design in a
| while but still having a rough feeling for costs I was a bit
| confused.
| NoiseBert69 wrote:
| Honestly: no one of the bigger players in the industry pays the
| prices you see on Digikey/Mouser/Farnell (with the exception
| maybe for prototyping stuff). Often you have direct delivery
| contracts with the vendors.
|
| That the ADS1115 costs <$1 on LCSC means they buy millions from
| them every year. They are one of the biggest trustable players
| in Asia.
|
| I have access to our internal STM32 pricing. You'd be shocked.
| the__alchemist wrote:
| H7s for <$1? I get confused whenever people talk about paying
| $0.69 for an MCU!
| squarefoot wrote:
| 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
| NoiseBert69 wrote:
| I played around with the RISC-V from WCH.
|
| They are huge step ahead: the upcoming CH32H417 has
| pretty much all PHYs integrated (!). For 10/100M
| Ethernet, USB-C 5GBbps and USB HS 480Mbps. That
| dramatically reduces the components needed to get that
| stuff running.
|
| I also build a small robot with the ultra cheap CH32V003.
| That's a full fledged 48MHz microcontroller with 16kb
| flash and 2kb SRAM. Fun little thing.
|
| If you are used to the ST HAL you will be able to work
| with them within 10 minutes. Their API style is similar.
| rts_cts wrote:
| We buy low end STM32s in 10-100k quantities and pay
| shockingly low prices as you noted and that's through
| official channels. One of our other suppliers offered us some
| "compatible" parts that he "might be able to find" for about
| a quarter of the cost, but we declined.
| throwup238 wrote:
| Yep people are mostly paying for the added inventory risk and
| labor when buying from distributors. Anyone with a big enough
| order to have their own wafer and the time to wait can get it
| a hell of a lot cheaper, especially for rarer parts that
| aren't as popular.
|
| One supplier I developed a relationship with showed us their
| internal numbers and it was $1,000-3,000 per wafer for
| 130nm-180nm nodes with a minimum order of 25 wafers. Once the
| part is designed and the mask is made, the cost is mostly
| just the setup plus whatever they want for the IP. The
| silicon itself is often cheaper than the packaging around it.
| 0l wrote:
| LCSC is definitely genuine. I'm not sure why people are so
| surprised that companies like Mouser have insane markups.
| dorkypunk wrote:
| Because they are used to the even insaner markup of smaller
| retailers that would ask 10USD for an IC that cost 5 cents at
| bulk
| isoprophlex wrote:
| 4x the price, at approximately 4x the error (12 mV instead of ~3
| mV on the spec)
|
| Weirdly honest deal, haha.
| throwup238 wrote:
| _> So what's going on with the cheap parts? My best guess is that
| these are either quite good copies, or failed parts that somehow
| made their way into the hobbyist supply chain._
|
| The vast majority of counterfeit chips I've seen were from ghost
| shifts but IIRC TI fabs all their analog parts in house, I doubt
| they're ghost shift parts or failed QC.
|
| I think its probably a relabeled ADS1015.
| q3k wrote:
| Interesting, most of the counterfeits that affect me (eg. FTDI,
| STM32 clones) have been just straight up clones developed from
| scratch, not excess inventory / ghost shifts / packaged
| rejects. I guess it might be a digital/mixed-signal split, with
| the two worlds having different issues?
|
| (also interestingly the STM32 clones I've seen had stacked die
| flash because they didn't fab them in a technology that could
| also do flash, so you can easily tell the counterfeit from
| sanding down the package and looking for an extra set of
| bonding wires; it's also a cool place to access the internal
| flash bus if you wanna bypass some readout protection :) )
| throwup238 wrote:
| I remember the mess with FTDI clones back when I was still a
| hobbyist and buying stuff from eBay, but ever since I've
| started doing EE professionally I rarely run into anything
| that bad. You're not going to make a clone Marvell processor
| for example, but I've run into several ghost shift runs from
| a distributor.
|
| I don't usually buy from electronics markets in Shenzhen
| either so that probably helps.
| londons_explore wrote:
| Buy in bulk from the Shenzhen markets and sellers will be
| pretty clear that you're getting a clone, and will give you
| samples of that specific clone so you can QA your product
| with them. (Some popular devices have multiple clone
| suppliers).
|
| I now always buy clones where possible - whilst not all
| features are implemented and some specifications won't be
| met, the devices seem to match the original for
| reliability, and sometimes even come with their own cloned
| modded datasheet.
| jamesbowman wrote:
| Author here. I did consider this, as others have reported
| getting ADS1015 marked as ADS1115. If it were an ADS1015 the
| readout would be truncated at 12 bits. These parts definitely
| delivered 16 bits of readout.
| hex4def6 wrote:
| I worry about the demo boards being radically different in
| terms of layout etc. Even if you're using the same interface
| and power supply, the PCB may be affecting performance.
|
| Getting full spec performance out of an ADC requires having
| good layout power supply routing etc.
|
| I would transplant the chips from PCB A to PCB B and vice
| versa. See if the performance follows the chip or the PCB.
|
| Also check power consumption before / after board swaps. If
| they are fakes, that would be significantly different.
| londons_explore wrote:
| It doesn't take much crosstalk from some clock signal into
| the signal you're measuring to really mess stuff up...
|
| Many of these Dev boards are not produced with as much care
| or knowledge as the chip design itself.
| throwup238 wrote:
| Ah oops I missed that. Maybe an ADX111A then?
| gsmecher wrote:
| 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. 221/2, 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 cloned it
| (bad).
|
| See also: https://community.element14.com/members-
| area/f/forum/53365/n...
| q3k wrote:
| > or just cloned it (bad)
|
| What's wrong with cloning a chip functionality-wise? This
| is basically how the industry has operated since its
| infancy, and what gave us jelly bean logic parts and
| transistors, x86 and the PC revolution, ...
|
| (just talking about the cloning part here, not
| counterfeit markings or datasheet copyright infringement,
| or copying mask work)
| mschuster91 wrote:
| If it's an open clone that can be reasonably
| distinguished from software side and from looking at the
| part _and_ it doesn 't violate IP laws other than
| software patents, no biggie.
|
| Every clone of any sufficiently complex Thing will have
| subtle quirks and edge cases compared to the original and
| as long as I can work around them for only that specific
| clone model, that's easy.
|
| But clones that have no way of determining if the part is
| a clone? That's bad to even _exist_ because unscrupulous
| actors will go and repackage "legitimate clone" chips
| into faked originals if the price difference is big
| enough.
| gsmecher wrote:
| There's nothing wrong with an open clone when everybody
| is acting in good faith. (In fact, "good faith" does not
| even necessarily mean "according to the letter of the law
| in $jurisdiction". Sometimes the law is an ass.)
|
| However, there's nothing more toxic to an OEM than a
| vendor relationship founded on dishonesty. I know I
| shouldn't trust them, they know it too, and even if it
| seems advantageous at first I shouldn't be surprised when
| they turn on me.
|
| Since these parts are being sold as genuine TI parts, I
| don't care whether the clone is physically faithful or
| just functionally faithful - I should treat it like it's
| poisonous.
| brcmthrowaway wrote:
| Has there been any updates on ADC technology? What does SKA/CERN
| use?
| the__alchemist wrote:
| Curious too. The part in question has been around for a while.
| lokimedes wrote:
| My lazy answer is to search for ADC on https://cds.cern.ch
| willis936 wrote:
| Well, if you're trying to measure DC extremely accurately the
| old stuff is still golden. Multi-slope is the gold standard and
| no one will sell you one. Delta-sigma get most of the way
| there.
|
| https://youtu.be/upTgM_S5rAQ
|
| And if you want to see CERN's multimeter, check this out.
|
| https://youtu.be/D28uSzCs7-k
|
| Marco Reps is a treasure.
| NoiseBert69 wrote:
| I still have a huge trauma coming from the ESP32 ADC. Why don't
| they integrate _good_ ADCs? We are waiting for ages now.
|
| Non-linear as hell - and evil side effects once you use the
| calibration curves.
| throwup238 wrote:
| _> Why don 't they integrate good ADCs?_
|
| There are a bunch of reasons but the primary reason is that
| good ADCs are made using a different mixed signal process than
| microcontrollers. MCU ADCs are capacitive charge-balancing
| successive-approximation type which limits their sensitivity
| and precision.
|
| Standalone ADCs also eliminate significant sources of noise
| like temperature fluctuations and electronic noise (the digital
| logic on the chip often runs at less than 1Mhz for example)
| 15155 wrote:
| Standalone ADCs are often SARADCs as well (and are specified
| as such.)
| throwup238 wrote:
| The ones I've used were mostly delta sigma modulation ADCs.
| I think charge balancing caps out at 12 bits or so.
| chillingeffect wrote:
| If hate the esp32 adc, let me introduce you to its "fpu." Or
| its external flash and memory...
| NoiseBert69 wrote:
| But no real competition for on-chip Wifi/BLE around.
|
| Only ugly two-chip solutions or hyper exotic stuff with no
| community.
| bsder wrote:
| > But no real competition for on-chip Wifi/BLE around.
|
| No competition or no market?
|
| I can't imagine Espressif is selling much volume of these
| chips.
|
| The fact that they can't even fix their SPI module would
| tend to indicate that their engineering staff is _very_
| thin.
| monocasa wrote:
| They've sold a billion of the things.
|
| https://www.espressif.com/en/news/1_Billion_Chip_Sales
| Hello9999901 wrote:
| The price difference could be explained by LCSC purchasing in
| bulk directly from TI or similar and selling them at lower
| margins because their volumes are larger. I've seen "clone" chips
| sold at LCSC, but they're listed under a different brand (I can't
| recall one off memory unfortunately).
| NoiseBert69 wrote:
| Never had bigger issues ordering from LCSC. And I buy _a lot_
| of stuff from them.
| MountDoom wrote:
| > 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 unneeded subsystems of the
| chip.
|
| They're still not as good as standalone ADCs, but they're at a
| point where you can actually use them for 90% of things that
| require an ADC.
|
| In cases where you need more bits, there's a lot more that must
| go into the design, which is what gives me a pause about the
| article. There's nothing about the PSU the author is using or how
| he managed the MCU noise and RFI. So I don't know if the findings
| here are that these are knock-off devices with worse specs, or if
| his overhead LED lamp is causing a lot of interference.
| magicalhippo wrote:
| I tested a few STM32F103 dev boards, using a Siglent SDM3055
| multimeter and Siglent SPD330X power supply.
|
| The chip has a 12bit SAR ADC. Layout and board design mattered
| a lot, but even the worst ones had 10 bits worth, and the best
| one had nearly 12 bits effective.
|
| That was without doing too much on the software side, meaning
| the other modules weren't running, besides a single serial
| output. On the bad boards the serial affected it, but on the
| good board very little.
| parsimo2010 wrote:
| I think you might both be right- the author may be thinking of
| lower cost MCUs only aiming for tolerable ADC performance,
| while you might be thinking of all MCUs, even higher cost.
|
| The RP2350 has 9.2 ENOB on a 12 bit ADC. Sure, you might be
| able to decimate multiple samples to get more bits out of them,
| but the spec sheet supports the author's claim
| (https://www.raspberrypi.com/documentation/pico-
| sdk/hardware....). There are even lower cost MCUs like the
| CH32V003 that have even worse ADC performance.
|
| On the other hand, some MCUs can definitely do 10+ bits, such
| as the STM32H7 line which gets 13+ ENOB from a 16 bit ADC. This
| is impressive, but the H7 MCUs are literally an order of
| magnitude more expensive than the RP2350, so they might not be
| something the author tinkers with much.
| https://www.st.com/resource/en/application_note/dm00628458-g...
| ryukoposting wrote:
| Glad I wasn't the only one thinking this.
|
| The paragraph ending with "Compare that with a microcontroller
| ADC with a fixed 3.3 V range: 9 ENOB steps are ~6 mV" also
| seems to insinuate that no MCU has an analog reference that's
| independent from the supply, which just isn't true at all.
| Hell, NXP has a few that have a built-in _programmable_
| reference.
| the__alchemist wrote:
| Ooh this is interesting! I've seen some big price differences
| between Digikey and LCSC at small volumes; not sure! You can also
| sometimes buy direct from TI.
|
| Of interest from early in the article: I'm curious how these
| external ones compare to onboard, e.g. STM32's. Btw, the TI one
| listed is actually pretty simple to use in comparison. The ST
| integrated ones have more config and hardware considerations,
| e.g. complicated calibration procedures, external VREF
| (mentioned) etc. So, if you do app the config, is the integrated
| one as good?
|
| The integrated ones usually have nice ways to integrate with
| timers and other onboard periphs.
| ZeroConcerns wrote:
| Well, I guess a whole-three-genuine-US-dollars is actually pretty
| expensive for an ADC, and that the person-in-charge-of-your-BOM
| in one of the countries that can actually still manufacture
| things can get one for _way_ less than that.
|
| Does it work? Well, does your design power up during factory
| testing, and then pass whatever things your rig (hope you made a
| few!) has in mind? Well, then, yes, in fact it does...
| LeifCarrotson wrote:
| These numbers add up fast when you have dozens or hundreds of
| components on your board. A $3 part is often one of the most
| expensive items on a board! If you're trying to get something
| shipped to consumers for $20 each, with an enclosure,
| packaging, shipping, retail markup, and profit...that's a huge
| price disparity.
|
| Also, and perhaps more importantly, the test rig is a lot
| simpler and a lot cheaper if you can generally trust
| manufacturer data. Sure, send off a few samples (likely
| prototypes with parts from Digikey instead of LCSC) to run
| extended testing in an environmental chamber with thermal
| imaging, build an endurance test rig that pushes the button
| once a second for four weeks to simulate once-daily use for
| years, whatever you want to do...but after that, if TI says
| it's good from -40 to +125, you're going to trust them on a lot
| of the edge cases.
|
| Do 100% testing of the things you can test in-circuit if you
| can - power it up at room temperature and make sure it works
| once - but that doesn't mean you get the actual rated
| performance across all published environmental conditions.
| RobKohr wrote:
| ADC = Analog to digital converter
|
| Takes an analog signal from something like light or sound and
| convert it into a digital signal.
|
| Acronyms introduced in an article should be spelled out at least
| once please.
| slices wrote:
| I thought they were talking about League of Legends players,
| whoops
| abraae wrote:
| I'd like to know more about the world of ADCs. I've used the
| ADS1115 with success but only at very slow speeds.
|
| On the current project we started with an MCP3208 via SPI. It did
| the job but only has 8 channels and it's slow (100K samples per
| sec).
|
| To get something faster we switched to ADS7953. It has 16
| channels and runs 10 times faster. It's somewhat more complex to
| code, and you can only get the highest sample rate if you scan
| the inputs in a predictable order. But it sure flies.
|
| To me, these chips feel like cars. The ADS7953 is somewhat of a
| ferrari, whereas the MCP3208 feels like a Toyota, simple to use,
| unimpressive performance.
|
| I'd love to know the industry background about how these
| varieties of ADC chips came to be and carved their own space in
| the world, and how widely they are used (millions? billions?).
| magicalhippo wrote:
| > To get something faster we switched to ADS7953. It has 16
| channels and runs 10 times faster.
|
| I recall reading about a project at CERN to design a 12bit ADC
| chip that could sample at tens of GHz, maybe 50 or more.
|
| I was perplexed at how they could achieve this.
|
| Turned out it was the same we programmers do. Parallel
| processing.
|
| They had taken a 12bit SAR unit which ran at like MHz rates,
| and just cloned it _many_ times. They then had a large analog
| multiplexer in front to route the signal to the active ADC unit
| in a round-robin fashion.
|
| That takes a lot of chip real-estate, and the analog muxer had
| to be carefully designed.
|
| For a simpler approach to speed there is Flash ADCs[1], which
| kinda brute-force it.
|
| For precision I know multi-slope ADCs[2] are often used.
|
| Sadly I don't know much about the history, and would also love
| to learn more about it. Bound to be some fascinating stories
| there.
|
| [1]: https://en.wikipedia.org/wiki/Flash_ADC
|
| [2]: https://www.analog.com/media/en/training-
| seminars/tutorials/...
| cycomanic wrote:
| 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?).
| londons_explore wrote:
| 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.
| Junk_Collector wrote:
| Keysight at least, has a fab where they make their own
| ADCs. Those are something like ENOB 6, 10 bit raw up to
| 120GHz and are used in their oscilloscopes but can also
| be purchased standalone.
|
| Oscilloscopes also have a significant amount of
| additional front end conditioning, probe control, channel
| timing, and analysis software built into them. Most of
| the math functions on oscilloscopes use custom ASICs that
| work off the raw bits coming from the 120GHz digitizer
| which is non-trivial even just to receive. Calling it a
| plastic case around a digitizer is disingenuous.
| Junk_Collector wrote:
| I think you are thinking of this video:
| https://www.youtube.com/watch?v=DXYje2B04xE
| dekhn wrote:
| (CERN does a ton of cool electronics design, I didn't realize
| how much modern physics _is_ electrical engineering).
| grishka wrote:
| > The ADS7953 is somewhat of a ferrari, whereas the MCP3208
| feels like a Toyota, simple to use, unimpressive performance.
|
| What about the AD9226? It only has a single channel but can do
| up to 65 MSa/s at 12 bits. I bought one as a module for around
| $12 on AliExpress to experiment with software decoding of
| analog video. I only run it at 20 MSa/s and only use 8 bits
| because, funnily enough, the limiting factor is the speed at
| which I could get the data into my laptop. I connected it to a
| Raspberry Pi Zero and use the SMI peripheral as described here:
| https://iosoft.blog/2020/07/16/raspberry-pi-smi/
| theamk wrote:
| For the curious: that blogpost does not mention the Pi model
| explicitly, but one of the links refers to BCM2835. This
| means Raspberry Pi Model 1.
| abraae wrote:
| The article does reference pi 3b and zero W.
| abraae wrote:
| That is very interesting, especially using SMI to talk to
| rpi. Never seen SMI used in anger before.
| NoiseBert69 wrote:
| Ultra high-speed ADCs are extremely ugly to handle with
| microcontrollers. That's mostly FPGA territory: toggle its
| pins, suck the data from the ADC and offer them on a friendly
| parallel bus for a microcontroller (USBC->Parallel interface
| from FTDI).
|
| They need a lot of pins to be toggled. Otherwise they spit out
| no data.
|
| And a lot of manual stuff means it's super DMA unfriendly. And
| you need DMA for high-speed stuff.
| Neywiny wrote:
| Still unsure if the lifcl-33U will make it into these
| products. Integrated 5gbps phy
| dazhbog wrote:
| Digikey's markup is the issue.. most people in Asia buy from lcsc
| or agents, that can get parts 2-10 times cheaper.. In this case
| both parts are genuine just different batch/year/production
| location probably..
| a-dub wrote:
| i wonder if the clock performance is worse too...
| cushychicken wrote:
| OP is making comments about poor performance single cycle of a
| sigma delta ADC.
|
| Single cycle readings defeat the point of sigma delta ADC setups.
|
| You're taking many high noise samples and averaging them over
| time to get a better picture of the average voltage.
| LeifCarrotson wrote:
| OP is using the chip with the data rate set to 8 samples per
| second.
|
| Natively/internally, it runs at 860 samples per second, and you
| can configure it to provide that data at a lower sample rate at
| lower noise levels by averaging multiple readings together
| internally.
| Aurornis wrote:
| > Single cycle readings defeat the point of sigma delta ADC
| setups.
|
| The ADC's internal delta-sigma ADC takes a lot of samples at a
| much higher modulation frequency and presents them as a single
| output value.
|
| You do not get the direct delta-sigma output from an ADC like
| this. The internal logic handles that for you. It's okay to
| take single samples of the output.
| zsellera wrote:
| Most companies have region-specific price lists. My Spotify
| subscription costs about 60% of what the same plan costs in the
| US (2200 HUF vs. 11 USD). In the electronics industry, everyone
| has a separate price list for China.
|
| Btw. the western list price is just an indicative at-most number
| anyway. Even a small-sized project gets discounted prices when
| you start talking to a sales rep.
| torginus wrote:
| Why would it be bad for that price? Highly accurate ADCs are
| pretty easy to make, provided you don't need a high sample rate,
| thanks to the magic of signal processing. Delta-sigma ADCs, and
| ramp ADCs can use a single bit of digital input + some pattern
| hold circuitry to do incredibly accurate measurements, it's just
| they take some time.
|
| If you want a flash ADC that can do 16 bit (and can do 16 bit at
| 100Mhz), however you'll have to probably mortgage your house.
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