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| Evolution of usb connector? |
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| IDEngineer:
--- Quote from: Buriedcode on December 24, 2018, 07:02:25 pm --- --- Quote from: IDEngineer on December 24, 2018, 04:08:39 pm ---To extrapolate, your argument is like saying that since we have Intel i9 processors available, there's no need for PIC microcontrollers... the i9 can do it all! Sure, that's true, but it doesn't mean the i9 is always and everywhere the best or most optimal answer. Sometimes an i9 would be massive overkill, all of the overhead required to implement an i9-based system being far too much for a simple application. The same is true for USB vs. "simple serial" communications. --- End quote --- I see your point, but I think you've got the wrong end of the stick here. No-one is suggesting we replace SPI/I2C or RS232 with USB, or that simpler protocols shouldn't be used, I'm not sure where you got the idea from and I don't know where to start to point out whats wrong with comparing the two, they occupy different roles. I have never used USB for IC-IC communication... in fact I can't think of any instance where one would have to choose between using USB or SPI, since they serve different purposes. Simpler protocols serve their purpose, no-one is claiming otherwise. --- End quote --- I'm not talking about intra-PCB communications. I'm specifically referring to inter-PRODUCT communications over short distances. I2C is already used in this manner in quite a few applications. I have to admit, I was surprised by that at first, since like you I viewed SPI and I2C as inter-chip and intra-PCB comm schemes. But over the last couple of years I've run into dozens of products (remote sensors especially) that are tied back to the host machine using SPI and especially I2C using many feet of cabling between discrete enclosures (a host and some remote device). In other words, basically exactly the physical interconnection mechanisms commonly used for USB. I presume these manufacturers arrived at the same conclusion I have: USB is great, but overkill for many situations, so do something better suited to the task at hand. I'll have to revise my earlier comments and say that what I'd like to see is a FORMAL adoption/recognition of what appears to already be an informal standard of using SPI and I2C for short distance, lower bandwidth communication. In particular, a connector standard would go a long way to making this a recognized option in an Engineer's spectrum of solutions. Anyway, I too apologize for my part in somewhat hijacking this thread. However, I do feel this issue deserves discussion. Perhaps its own thread would be justified? |
| westfw:
--- Quote ---disagree that a "simple serial" standard would automatically endure feature creep. --- End quote --- Have you read the "Async PPP" specification(s)? :-( X/Y/Zmodem/Kermit? AX.25? IIRC, some of the current video connection standards include an I2C interface:https://hackaday.com/2014/06/18/i2c-from-your-vga-port/ And the SD card reader should be able to do SPI. Good luck with drivers, though. (and getting back somewhat to the original topic: What are you going to use for connectors?) BTW, speaking of feature-creep: I2C and SPI are not immune, either, especially WRT ever-increasing clock-rates. The chip I've been looking closely at most recently supports 3.4MHz I2C, but only SOME of the pins connected to I2C controllers actually manage to fully support the electrical side of the spec. |
| Siwastaja:
--- Quote from: westfw on December 24, 2018, 09:32:42 pm ---BTW, speaking of feature-creep: I2C and SPI are not immune, either, especially WRT ever-increasing clock-rates. The chip I've been looking closely at most recently supports 3.4MHz I2C, but only SOME of the pins connected to I2C controllers actually manage to fully support the electrical side of the spec. --- End quote --- I2C is interesting. For what it is, it's a massively overengineered piece of feature creep. It's just that absolutely no one uses all those features! People use I2C for simplicity, and if you are requiring 3.4Mbit/s communication, complex multi-master modes etc., you are probably using the wrong thing. Most people understand this and won't use I2C for those tasks, even if it, theoretically, could support it. Yet we as designers are exposed to stupid details originating from the I2C complexity no one uses. For example, configuring an STM32 I2C peripheral requires understanding of the existence of Multi-Master mode, and configuring things properly, otherwise the standard case (one master) won't just work. --- Quote from: soldar ---Um, guys? The topic of this thread is the evolution of the USB connector. Not about how the USB protocol compares with the cost of tea in China during the monsoon season. Can we get it back on track? Please? --- End quote --- I'm 100% positive that if someone still has something to say about the connector evolution, they'll speak up just fine, thanks for your consideration! In the meantime, since there is no way to force people discuss about something, what you are going to do? While you always could forbid discussion (silencing the thread, burying it), that's usually a very bad idea, as long as the discussion has merit in itself, and stays civil. That's how real discussions with real people work, after all. Unnecessary self-sensorship sucks. |
| IDEngineer:
Since this thread may be searched by others in the future asking about I2C, here are some links related to long-distance I2C: * http://www.nxp.com/docs/en/application-note/AN11075.pdf ("Driving I2C-bus signals over twisted pair cables with PCA9605") * http://www.ti.com/lit/ds/symlink/p82b715.pdf (TI's version of the same thing) * http://hackaday.com/2017/02/08/taking-the-leap-off-board-an-introduction-to-i2c-over-long-wires * https://www.i2cchip.com/i2c_connector.html ...and the Stack Exchange article where I encountered them: * https://electronics.stackexchange.com/questions/47056/is-there-any-definitive-i2c-pin-out-guidance-out-there-not-looking-for-a-stand There's a LOT more in a Google search about I2C over long wires, but the above links will give you a very helpful start. Now all we need is a standardized connector... and in some of these links there psuedo-standards being used by lots of people, including recommended pinouts that take power supply reversal, etc. into consideration. Support IC's... app notes... a groundswell of companies already using I2C for long wires... I think we're closer to a simple serial standard than some folks might believe! |
| westfw:
Thanks for posting this info. I'm still going to be curmudgeonly, though! --- Quote ---a groundswell of companies already using I2C for long wires... I think we're closer to a simple serial standard --- End quote --- "Support ICs." (heh. The TI and NXP chips don't seem to be compatible. NXP uses a pair for each signal, TI a single wire.)"No standard connector."Assorted uC's that I keep seeing "having trouble getting I2C to work right" messages...Other uC's that "Support I2C on any SERCOM/UniversalSerial/etc port, except the ones that don't quite meet the electrical specs."Address conflicts and limitations. Are you sure that this will wind up simpler than USB? I mean, it wasn't an inherent weakness of the UART protocols that made RS232 such a PITA in practice, it was the lack of ... formalization of all of the "other stuff" needed to communicate. And perhaps it is that USB *has* formalized a bunch of that stuff that makes it so (apparently) complex. |
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