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| Evolution of usb connector? |
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| Siwastaja:
--- Quote from: westfw on December 24, 2018, 04:19:06 am ---I'm just trying to insist that people recognize that the simplicity of "rs232" comes with a pretty substantial cost. At one "cpu involvement" per millisecond, USB gets you something like 512kbps, a UART gets you about 10kbps, and bit-banging gets you about 1kbps. All those settings and things that "USB Complexity" adds, you now have to be sure to do correctly, manually. --- End quote --- It's completely normal to have an UART peripheral with a FIFO and DMA connectivity, and a driver layer that handles the DMA transfers, and this can provide even lower CPU than USB due to less housekeeping activities. And, it's still orders of magnitude simpler than the USB stack - at least when the asynchronous separate rx&tx byte streams with no HW packet delimiting is what you want... The issue there isn't strictly technical. It's just that exactly due to the low-level simplicity, UARTs have the history of being used in various ad-hoc ways, everybody implementing their own software layers (often minimal, for the specific task) and their own connectors, their own signaling levels (compare RS232, TTL, 5V or 3V3 CMOS, optocoupled MIDI...) OTOH, USB is ground-up designed for connecting all imaginable (and non-imaginable, by extending the standard later) PC peripherals to a PC, and do this invisibly to the consumer end user. This is not even apples to oranges; this is apples to space shuttles. The things are so vastly different that when you compare one specific case (such as connecting a mouse), you always leave other people unsatisfied, and the argument can easily go on. |
| westfw:
--- Quote ---I can tell you this... the next clean-sheet design I do that doesn't require full USB bandwidth I will push hard for SPI or I2C as its serial interface --- End quote --- I guess it depends on what you want to talk to as well. Most of my "rs232 is horrible" comments apply mostly to the "host" or PC side. Personally, I wish Ethernet had ended up being used for a lot of the applications currently served by USB. Between Ethernet and various IP protocols, I think a lot of the same capabilities are present, and the IP world (IETF, I guess) seems to have managed to define a lot of things in much more "straight-forward" ways (and less proprietary.) --- Quote ---I used external COM chips, cranked up, fiber drivers with tristate buffers and ... FIFO buffers with trigger latches. ... It's not rocket science --- End quote --- Doesn't sound "simple" any more, though. :-) |
| digsys:
--- Quote from: westfw --- Doesn't sound "simple" any more, though. :-) --- End quote --- Ahhhh but back then, the newest / best external comms chips only had 64-256 byte buffers, and 1Mb ish For MOST applications that was often well enough, so it just bolted on to your MPU, usually in expanded bus mode. BUT if you had very large data streams, and/or high traffic, you needed to "roll" your own. Usually the "extra" pcb was a standard add-on, often I'd make it part of the RS232 connector IF. Even in vehicles, I prefer this method to the DREADED CAN bus !! People "bitch" about USB :-) ... CAN is a worse asswipe :-) |
| soldar:
--- Quote from: tooki on December 20, 2018, 04:57:13 pm ---Christ on a cracker, man... What produced the modern USB connectors (culminating in USB-C) isn’t magic new materials. It’s simply ordinary engineering done to improve upon the shortcomings of what came before. The number of devices with USB today is probably orders of magnitude larger than all the computers in the world in 1995, and the use cases cover things never anticipated before. At this kind of scale, you discover issues that you wouldn’t have otherwise. And the economies of scale involved mean that you can amortize much more expensive R&D than you could have before, so we could spend more money designing better connectors to improve upon the last. And at this kind of scale, manufacturers can afford the more expensive tooling for higher-precision parts. --- End quote --- Yup. Evolution. Everything we have today is the product of a long evolution of conditions and possibilities. And this includes cultural and sociological conditions. Fifty years ago people expected things to be sturdy and long lasting. Even if possible, giving them tiny, flimsy connectors would result in complaints about how flimsy they are, how difficult to plug in, and how expensive. I have known people who would wreck USB connectors because they just could not get it into their heads that you cannot just jam in crookedly but with great force. The metal contacts on the mobo connector would bend and that would be the end of that USB port. But also, the technology just wasn't there yet. Look at any consumer product from around 1950 and it looks incredibly crude with wiring harnesses and *humongous* connectors. That is what was technically and economically feasible at the time. Twenty five years later they were using printed circuit boards that were, by today's standards, also very crude. Today's PCB is the product of a very long evolution of the initial PCBs. Many tiny incremental steps which add up. Along the way many things have been tried which have been superseded or discarded. That is how evolution works. Asking why they didn't start out making USB-C connectors in the first place misses the historical picture. USB was an improvement over what there was at the time and that was all that was needed. And many other good improvements fell by the wayside. that is how evolution works. Sometimes it is not the best product technically speaking that wins out but others that, for various other reasons, won out. The ability to manufacture miniaturized connectors, switches, etc, has improved steadily over the decades. Especially the ability to manufacture them economically. It is not like it was always there. and the demand wasn't there either. Look at any mains power plug of any kind, be it Schuko, Nema or British. They are all bulky and wrong on so many levels but they were designed in their time with the demands and possibilities of those times. Today they remain because changing would be too costly. If we had to design a mains power plug today it would be nothing like what we are using. |
| coppercone2:
what would it look like? the mains plug |
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