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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?

#61

Post by Terr_ »

jacquesm wrote: post #54
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 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.

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.)

Re: How bad can a $2.97 ADC be?

#62

Post by pinkmuffinere »

Lerc wrote: post #41
15155 wrote: post #33

Earlier quoted context omitted.

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.

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.

Lol I love the deep cut to LOTR! Took me a sec but then brought me so much joy. Viva la nerds!

Re: How bad can a $2.97 ADC be?

#63

Post by NoiseBert69 »

beachy wrote: post #29

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 rat…

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.

Re: How bad can a $2.97 ADC be?

#64

Post by beachy »

grishka wrote: post #47
beachy wrote: post #29

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 rat…

> 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 sp…

That is very interesting, especially using SMI to talk to rpi. Never seen SMI used in anger before.

Re: How bad can a $2.97 ADC be?

#65

Post by beachy »

theamk wrote: post #60
grishka wrote: post #47

Earlier quoted context omitted.

> 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 sp…

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.

The article does reference pi 3b and zero W.

Re: How bad can a $2.97 ADC be?

#66

Post by fullstop »

q3k wrote: post #2

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,…

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

Re: How bad can a $2.97 ADC be?

#67

Post by Neywiny »

NoiseBert69 wrote: post #63
beachy wrote: post #29

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 rat…

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.

Still unsure if the lifcl-33U will make it into these products. Integrated 5gbps phy

Re: How bad can a $2.97 ADC be?

#68

Post by mschuster91 »

q3k wrote: post #51
gsmecher wrote: post #37

Earlier quoted context omitted.

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…

> 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)

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.

Re: How bad can a $2.97 ADC be?

#69

Post by kens »

fullstop wrote: post #66
q3k wrote: post #2

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,…

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

I have enough projects already, so I'm staying quiet here :-)

Re: How bad can a $2.97 ADC be?

#70

Post by fullstop »

kens wrote: post #69
fullstop wrote: post #66

Earlier quoted context omitted.

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

I have enough projects already, so I'm staying quiet here :-)

I won't tell if you won't tell.
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