rickman <spamgoeshere4@yahoo.com> wrote in message news:<405A4DA3.3260FD95@yahoo.com>...> For example, the give away Cypress PSOC invention board uses USB. One > chip, likely cheaper than an RS-232 converter, provides the USB > interface. The connectors come in two flavors, small and tiny. It was > designed from the get-go (not gecko) to be low cost and yet run at 12 > Mbps at 5 meters. I like it and I will be getting very used to it. >Yes, but we need 9600Bd at up to 1km with a few kV isolation. We use a 20mA-loop dongle stuck into the PC COM port. Works like a charm and the only thing that can burn it is a lightning strike - and even then the PC never gets damaged, only the dongle. So, building USB into our product doesn't make sense because it's not near the PC. We've already got an ethernet tcp/ip module, but that's not much use if there isn't already a LAN running around the place. Using USB/RS232 converters seems to be the only option, but the few types we tested cause delays so we had to tweak our PC software to get them to work. The question is, will all USB/RS232 converters behave in the same way? I'm thinking of delays and out-of-the-ordinary stuff, like changing the parity on-the-fly between two sent characters etc. Viktor
Demise of the COM port?
Started by ●March 18, 2004
Reply by ●March 19, 20042004-03-19
Reply by ●March 19, 20042004-03-19
On 2004-03-19, Darin Johnson <darin_@_usa_._net> wrote:>> As far as cheap: DB-9 (and especially DB-25) connectors are >> expensive both in parts cost and board-space. > > The product I used always just had two or three pins rather than > full connectors.I've never seen a PC with anything except DB-9 or DB-25 connectors for RS-232 serial ports. Macs used to use mini-DIN connectors, but those aren't that cheap either.> Dirt cheap. The software was cheap too since driving a serial > console from minimally sized boot and diagnostic code is > simple Doing an ethernet console was much more expensive.I don't see what that has to do with the cost of a PC. -- Grant Edwards grante Yow! Are BOTH T.V.S on?? at visi.com
Reply by ●March 19, 20042004-03-19
On 19 Mar 2004 22:13:48 GMT, the renowned Grant Edwards <grante@visi.com> wrote:>On 2004-03-19, Darin Johnson <darin_@_usa_._net> wrote: > >>> As far as cheap: DB-9 (and especially DB-25) connectors are >>> expensive both in parts cost and board-space. >> >> The product I used always just had two or three pins rather than >> full connectors. > >I've never seen a PC with anything except DB-9 or DB-25 >connectors for RS-232 serial ports. Macs used to use mini-DIN >connectors, but those aren't that cheap either.IIRC, a right-angle PCB mount DB-9M is less than a dime.>> Dirt cheap. The software was cheap too since driving a serial >> console from minimally sized boot and diagnostic code is >> simple Doing an ethernet console was much more expensive. > >I don't see what that has to do with the cost of a PC.Best regards, Spehro Pefhany -- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Reply by ●March 19, 20042004-03-19
"rickman" <spamgoeshere4@yahoo.com> wrote in message news:405A4DA3.3260FD95@yahoo.com...> Viktor Kesler wrote: > > > > First it was notebooks, now even desktop PCs are made with just one orno> > RS232 ports. > > What's happening? > > For us embedded engineers who have developed uC products thatcommunicate> > with PCs through COM ports, this situation is getting scary. > > I know USB/RS232 converters exist, but they're an added cost, very often > > make rebooting necessary and are often the cause of delays which cancause> > problems with protocols that worked well on genuine COM ports. > > > > The asynch interface may not be fast, but it's cheap, easy to isolate > > galvanically and most uControllers have it built in. > > > > Can we do anything about this trend? Wear 'COM port rulz' or 'USB gohome'> > t-shirts or something? > > Yes, you can get used to the change and start working *with* USB instead > of fighting it. The mighty oak tree breaks in the wind while the lowly > reed bends with it. :) > > For example, the give away Cypress PSOC invention board uses USB. OneGive away...where? It is $399 on http://www.cypressmicro.com/.
Reply by ●March 19, 20042004-03-19
On Fri, 19 Mar 2004 21:37:20 GMT, Darin Johnson <darin_@_usa_._net> wrote:>Max <mtj2@btopenworld.com> writes: > >> Some research in the US around the turn found that less than 1% of all >> RS-232 ports on PCs had anything plugged into them. Given the obvious >> advantages of USB, the switch made sense for the average joe. > >I think there's also an assumption that the typical user has upgraded >to a late model OS that supports USB. If they left the serial and >parallel ports alone, how else could they force the user to abandon NT?Well, they could bundle it with the machine. Not exactly "forcing," but 99% (or more) of their customers will take the path of least resistance.> >> >Why? What exactly is wrong with a simple, cheap serial port? >> >> Apart from the ridiculous interrupt overhead in any modern OS, you >> mean? > >USB doesn't rank very high in software efficiency when you're using >low speed devices like keyboards and mice.There's a huge difference between "software efficiency" and "interrupt overhead," don't ya think?> >> There was no technical reason why they had to disappear from the Mac >> either. But why equip all PCs with an interface that very few people >> use? > >The problem with the "but very few people need them" argument is that >it moves the PC away from a general purpose one-size-fits-all machine >into a specialized machine. Ie, the PC was used a lot in engineering, >much more than Macs, precisely because it could be adapted to a wide >variety of uses.The last PC I bought came with a 6-pin mini-DIN keyboard connector, so I can't use my Northgate Omnikey 102 keyboard (which has a 5-pin DIN connector) on that system. Does this mean it is any less a "general purpose one-size-fits-all machine?" No, it means I buy an adapter that allows my old keyboard to work. If I want a serial port, I can buy one. They are called "legacy" ports for a reason. Regards, -=Dave -- Change is inevitable, progress is not.
Reply by ●March 19, 20042004-03-19
In article <405b709b$0$177$a1866201@newsreader.visi.com>, Grant Edwards <grante@visi.com> wrote:> I've never seen a PC with anything except DB-9 or DB-25 > connectors for RS-232 serial ports.I have never seen a PC using a DB-9 connector for RS-232 serial ports. The ones I have seen use either a DE-9 connector or a DB-25 connector. -- G�ran Larsson http://www.mitt-eget.com/
Reply by ●March 19, 20042004-03-19
Viktor Kesler wrote:> rickman <spamgoeshere4@yahoo.com> wrote in message news:<405A4DA3.3260FD95@yahoo.com>... > > >>For example, the give away Cypress PSOC invention board uses USB. One >>chip, likely cheaper than an RS-232 converter, provides the USB >>interface. The connectors come in two flavors, small and tiny. It was >>designed from the get-go (not gecko) to be low cost and yet run at 12 >>Mbps at 5 meters. I like it and I will be getting very used to it. >> > > > Yes, but we need 9600Bd at up to 1km with a few kV isolation. > We use a 20mA-loop dongle stuck into the PC COM port. Works like a > charm and the only thing that can burn it is a lightning strike - and > even then the PC never gets damaged, only the dongle. > > So, building USB into our product doesn't make sense because it's not > near the PC. We've already got an ethernet tcp/ip module, but that's > not much use if there isn't already a LAN running around the place. > > Using USB/RS232 converters seems to be the only option, but the few > types we tested cause delays so we had to tweak our PC software to get > them to work. > > The question is, will all USB/RS232 converters behave in the same way? > I'm thinking of delays and out-of-the-ordinary stuff, like changing > the parity on-the-fly between two sent characters etc.Just _specify_ a PC WITH a COM port ?. Something that needs 1km reach opto isolated Comms does not sound too 'home PC' anyway... There are plenty of Motherboards made still with COM ports. This PC has two 9 pin COM ports on the mother using stacked connector technology to pack in PS2x2, USBx4,Ethernet, VGA, and COMx2 ports into a shrunk case. The mass school/consumer market may not dictate com ports, but there are solutions available, and will be for some time. Simple USB/RS232 converters will always have latency problems, but one solution is to use more smarts 'in the dongle', so the serial latency is outside the PC. Cygnal have a USB+FlashuC that is well suited to this type of latency reduction. What WOULD be nice is one with the fastest USB 2.0 speeds :) -jg
Reply by ●March 19, 20042004-03-19
On Fri, 19 Mar 2004 21:37:20 GMT, Darin Johnson wrote:>> Some research in the US around the turn found that less than 1% of all >> RS-232 ports on PCs had anything plugged into them. Given the obvious >> advantages of USB, the switch made sense for the average joe. > >I think there's also an assumption that the typical user has upgraded >to a late model OS that supports USB. If they left the serial and >parallel ports alone, how else could they force the user to abandon NT?Not all that many people upgrade an OS on an existing machine. Increasingly, the trend is to only adopt a new OS version when replacing the whole machine. This seems to apply across all OS flavours, and is not restricted to Windows (e.g. MacOS X).>> >Why? What exactly is wrong with a simple, cheap serial port? >> >> Apart from the ridiculous interrupt overhead in any modern OS, you >> mean? > >USB doesn't rank very high in software efficiency when you're using >low speed devices like keyboards and mice.You're going to have to explain what you mean by "software efficiency". So far as I can see, much of the PC's overhead in acting as a USB host has been pushed off to hardware (at least in Intel chipsets). If you're referring to the high IRQL of the keyboard and mouse handlers in Windows, that's a conscious design choice to favour UI responsiveness. Go argue with Dave Cutler, not me ;o)>> There was no technical reason why they had to disappear from the Mac >> either. But why equip all PCs with an interface that very few people >> use? > >The problem with the "but very few people need them" argument is that >it moves the PC away from a general purpose one-size-fits-all machine >into a specialized machine.I'm sorry, but that's a really fatuous argument. Do you carry an elephant gun around with you? Obviously, it's not something you're going to use often ... but you never know ...> Ie, the PC was used a lot in engineering, >much more than Macs, precisely because it could be adapted to a wide >variety of uses.Which features, specifically, did you have in mind? I think you'll find that Macs have mostly had much the same hardware as the PC, CPU apart - just a couple of years later. MacOS, before it became a Unix clone, was absolutely horrible to write code for ("RAM doublers", anyone?). Didn't stop Apple from charging a fortune for the privilege of using their tools, though. -- Max
Reply by ●March 19, 20042004-03-19
On Thu, 18 Mar 2004 20:40:09 +0100, Viktor Kesler wrote:>... RS232 ports. > >The asynch interface may not be fast, but it's cheap, easy to isolate >galvanically and most uControllers have it built in.Asynch serial may be built in, but RS-232 requires a level converter. -- Max
Reply by ●March 19, 20042004-03-19
Guy Macon wrote:> Max <mtj2@btopenworld.com> says... > >> What's wrong with progress, anyhow? RS-232 is already well past >> retirement age. Let it die in peace, I say. USB is a vast improvement. > > Next thing you will be telling me that I should be using this > newfangled "World Wide Web" rather than good old fashoined > Gopher Servers...No, you should use Telix and a dialling list to various RBBSs. -- Chuck F (cbfalconer@yahoo.com) (cbfalconer@worldnet.att.net) Available for consulting/temporary embedded and systems. <http://cbfalconer.home.att.net> USE worldnet address!
