EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: DavidAlfa on August 10, 2023, 02:40:45 pm
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Saw this today. That's a pretty cool FPGA-like matrix interconnection concept.
I also discovered the CH446 (The analog switch array doing the magic".
Yeah, yeah, I know 75ohm RDS on is not great, but it's low enough for a majority of purposes.
I'm not a fan of the RGB-everywhere thing, but the real-time routing with the wire colour picker is awesome.
https://www.youtube.com/watch?v=lvTNR78cKvc (https://www.youtube.com/watch?v=lvTNR78cKvc)
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Is that an Arduino Nano or something else?
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The hardware under the "breadboard" is a quite neat Idea, but I quite dislike this concept of drawing breadboard wires on you monitor.
It would have been much better if you could draw a regular schematic (maybe even in KiCad) then put an IC on your breadboard and it just does the connection instead of having to draw the wires one by one.
And with USD 300 this thing is also not very affordable:
https://www.tindie.com/products/architeuthisflux/jumperless/ (https://www.tindie.com/products/architeuthisflux/jumperless/)
https://hackaday.io/project/191238-jumperless (https://hackaday.io/project/191238-jumperless)
He also fuzzed out the matrix switch IC's on his indie page, which is a bit strange, because he does mention he uses CH446Q crosspoint switches (and 12 of them). which has an 8x16 switching matrix: https://www.wch-ic.com/products/CH446.html (https://www.wch-ic.com/products/CH446.html) (Datasheet attached too).
You also loose some flexibility because of it's limited supply range. Vcc for the chip is max 12V. It all works fine, but the main exellence for breadboards is to mix analog and digital circuits. For example some pre-amplier, analog signal conditioning and an adc into a uC. This board probably handles the digital logic signals just fine, but I doubt it handles the analog parts very well.
Combine that with that most people buy cheap unreliable chinese breadboards instead of higher quality busboards (or other brand) while the price difference is quite small and I don't see a big market for this. But still, the concept is quite intriguing and there has clearly been put quite a lot of effort in this project and I do wish him well.
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On a sidenote, Octopart does not list the CH446. "Western companies" bet that these switch matrices are put into expensive equipment and customers are ready to pay EUR20 or so for such an IC (although switch matrix size and bandwidth varies) LCSC lists this part for USD1.5 (10+) https://www.lcsc.com/search?q=ch446 (https://www.lcsc.com/search?q=ch446)
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It's not practical, and definitely not sexy anymore after seeing $300 in it, but still, it shows great creativity, and I love that kind of overkill ideas.
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Hey thanks for posting this! I'm the guy who makes these.
I'll answer whatever questions I see here.
Is that an Arduino Nano or something else?
Yeah the header on top is labeled for an Arduino Nano, but the board doesn't actually care what you stick in there. There are cuttable solder jumpers to disconnect the power supplies and reset lines to the header so you don't hurt whatever other thing (like a logic analyzer, etc.) you happen to stick in there. I picked the Nano because you can get basically any type of microcontroller in that form factor and it was small enough to fit.
The hardware under the "breadboard" is a quite neat Idea, but I quite dislike this concept of drawing breadboard wires on you monitor.
It would have been much better if you could draw a regular schematic (maybe even in KiCad) then put an IC on your breadboard and it just does the connection instead of having to draw the wires one by one.
I agree, for anything more complex than these examples, Wokwi is pretty cumbersome. What's actually happening there is the Python script just pulls the diagram.json file and parses it (even though there's also a parser on the Jumperless itself too) into a list of nodes that are formatted like:
{
NANO_A0-26,
SUPPLY_5V-15,
DAC1_8V-2,
45-52,
}
(there are a few other ways to format this, like t15-b15 )
and just sends that as text over the serial port and the Jumperless itself finds all the paths and makes the connections. The reason I'm saying all this is that it's super easy to write a parser for any format into this. I'll probably do the KiCad parser after I finish the Arduino library API for making connections.
And with USD 300 this thing is also not very affordable:
Yeah the BOM cost and everything is pretty high, so for now my margins are super thin to try to get these into as many people's hands as possible and hopefully they'll come up with new use cases for it. I want these to be cheap, but right now I don't have the volumes to get my costs down further.
He also fuzzed out the matrix switch IC's on his indie page, which is a bit strange, because he does mention he uses CH446Q crosspoint switches (and 12 of them). which has an 8x16 switching matrix: https://www.wch-ic.com/products/CH446.html (https://www.wch-ic.com/products/CH446.html) (Datasheet attached too).
Ha, I was thinking someone might think that when I posted it, I didn't intentionally blur them out, I was using a lens from a Russian night vision monocular that has no aperture control and is fixed at f1.5, a purely aesthetic choice. Here's a less artsy photo of the back.
[attach=2]
You also loose some flexibility because of it's limited supply range. Vcc for the chip is max 12V. It all works fine, but the main exellence for breadboards is to mix analog and digital circuits. For example some pre-amplier, analog signal conditioning and an adc into a uC. This board probably handles the digital logic signals just fine, but I doubt it handles the analog parts very well.
You're right that a digital-only breadboard would be completely useless, I run these CH446Qs at +-9V, which is a bit out of spec, but RDS and all the other specs get better at higher Vcc-Vss voltages and leaving them powered up for weeks hasn't killed any yet. So they'll pass any signal from +9V to -9V just fine. The chips are rated to 50MHz at 3dB, but the physical breadboard will probably have other plans with that frequency.
Also the 4 ADCs and 2 DACs are buffered and level shifted to deal with +-8V (well, one of each, the rest are shifted for 0-5V to keep some of that 12-bit resolution.)
So yeah, this was designed as an analog-first board, and digital just happens to fall inside the ranges it's built for.
I'm not a fan of the RGB-everywhere thing, but the real-time routing with the wire colour picker is awesome.
I fought the instinct to RGB it for so long, but using it involved a lot of counting breadboard rows without them. And when I gave in and had custom phosphor bronze breadboard clips manufactured, I figured I had too good of an opportunity to add a little slot for a WS2812C-2020 so I had to do it.
[attach=1]
I'm glad I did though, it really does help the experience of using it feel more natural. And you can adjust the brightness (they default pretty low already) to not melt your retinas. Unnecessarily bright LEDs are so annoying.
I should also mention that this thing is completely open source and all the files to build one of these yourself are on GitHub, and I'd be happy to help out however I can if you decide to go that route.
https://github.com/Architeuthis-Flux/Jumperless (https://github.com/Architeuthis-Flux/Jumperless)
And the breadboard shells and clips
https://github.com/Architeuthis-Flux/Breadboard3DmodelsJumperless (https://github.com/Architeuthis-Flux/Breadboard3DmodelsJumperless)
It's not practical, and definitely not sexy anymore after seeing $300 in it, vut still, it shows great creativity, and I love that kind of overkill ideas.
I think more important than just making the kind of jumper connections you'd make by hand, the fact that they can be connected and disconnected extremely quickly (~30 microseconds) and programmatically is what I think makes this more useful than just a breadboard for lazy people.
Like for modular synth people, have a control voltage input that switches around the order your filters are connected. Or just scanning the whole breadboard really quickly to sense when parts have been placed and maybe figure out what they are (there are 2 routable INA219 current sensors, some routable GPIO, as well as the DACs and ADCs, so the hardware to do that is there.) Or just for fun, sticking in a bunch of random parts and running an evolutionary algorithm to have it come up with a particular output for some given input.
I answered a few good questions on Reddit recently if you want to read through that.
https://www.reddit.com/r/arduino/comments/15epjel/i_just_finished_a_project_that_might_help_you_all/ (https://www.reddit.com/r/arduino/comments/15epjel/i_just_finished_a_project_that_might_help_you_all/)
And if anyone has any more questions, I'd be happy to answer them here too.