Much of this thread gives me a chuckle. I've had contact with areas which I suspect still use 20mA current loop in which USB or Ethernet would die imeadiately. And 20 mA might be preferred over fiber optic. The reason legacy hardware/software stays to become "legacy" is that it is the optimal solution for some class of problems.
Terminal emulators
Started by ●January 17, 2009
Reply by ●January 21, 20092009-01-21
Reply by ●January 21, 20092009-01-21
In article <hvu+9Khby1dJFARu@phaedsys.demon.co.uk>, chris@phaedsys.org says...> In message > <8a411655-4c62-4490-9f21-8cd7835e32bb@z28g2000prd.googlegroups.com>, > rickman <gnuarm@gmail.com> writes > >The fact that you judge serial ports as being "legacy" does not mean > >they shouldn't be used in new designs. Here is an excellent example > >of why. Much GPS equipment has used RS-232 serial port for NMEA > >compatible comms. There is no USB on the go equivalent. But many new > >units are coming out with only a USB port. So this new equipment is > >not compatible with applications requiring communications with other > >GPS equipment, not because the other equipment is "old", but because > >USB just won't work in this application. > > The problem depends on your application domain. 90% of MCU have serial > port and any one can do serial comms in 10 minutes which both hands tied > behind their back. >..> The problem is that many modern laptops don't have a serial port. Most > desktop PC's still have one AFAIK but lots of USB so many consumer items > have USB.About 6 months ago (maybe 9) one of my custoemrs deliberately bought a HP laptop because it had a Serial port and XP. What was the customer doing? Customer was setting up a field laptop, for an amateur archealogical group, and their ground resistance meter (very low volume product) had a serial port to dump the data..> USB is not the easiest thing to just knock up from scratch in an > embedded system.Agreed, how long before you need a 32 bit OS on temperature logger, just so it can be connected via USB. If you are not careful you end up with the "[USB] tail wagging the dog [embedded system]"> Also serial is universal and things like VT52 or VT100 you can almost do > in your sleep for virtually any screen. > > If PC's drop the one serial port most AFAIK mother boards have then > RS232 is not a good idea. But there is so much industrial use of RS232 > that I doubt it will happen for a long timeHalf the rouble is some customers who I know who would rather bit bang via USB from a PC to SPI devices, rather than have an onboard micro. Basically because they believe they have lots of processor ticks on a PC than on an embedded micro. -- Paul Carpenter | paul@pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.pcserviceselectronics.co.uk/fonts/> Timing Diagram Font <http://www.gnuh8.org.uk/> GNU H8 - compiler & Renesas H8/H8S/H8 Tiny <http://www.badweb.org.uk/> For those web sites you hate
Reply by ●January 21, 20092009-01-21
On Jan 21, 1:11=A0pm, rickman <gnu...@gmail.com> wrote:> As a "legacy" interface it is still supported on ***every*** PC made > that has USB and it will likely ***always*** be supported until PCs > are very different animals which will likely not be in my lifetime. >FWIW, we are still using punch cards for storing programs. They have just been virtualized into text files. The same thing seems to have happened to RS232. You can set up a virtual COM port on your PC that talks through USB, Ethernet or Wifi using the appropriate bridge. Depreciating serial ports on PCs was a good move since peripheral makers needed a nudge to get them all behind USB. Plus, average users don't really need a RS232 port other than for connecting peripherals that ought to be USB anyway. -Brad
Reply by ●January 22, 20092009-01-22
On Wed, 21 Jan 2009 19:09:01 -0800 (PST), bitbarf@gmail.com wrote:>On Jan 21, 1:11�pm, rickman <gnu...@gmail.com> wrote: >> As a "legacy" interface it is still supported on ***every*** PC made >> that has USB and it will likely ***always*** be supported until PCs >> are very different animals which will likely not be in my lifetime. >> >FWIW, we are still using punch cards for storing programs. They have >just been virtualized into text files. The same thing seems to have >happened to RS232. You can set up a virtual COM port on your PC that >talks through USB, Ethernet or Wifi using the appropriate bridge.Which USB dongle supports bit banging on RTS, DTR etc. lines at any reasonable speed ? More importantly, which USB converter controls the RTS control line in a timely way compared to the actual data bytes ? This is important when the RTS signal is used to control the data direction on a half duplex medium such as RS-485 or a half-duples radio transceiver. There are expensive special USB/RS485 converters that generate the data direction control internally, but this is not of much use when controlling a radio transceiver. Paul
Reply by ●January 22, 20092009-01-22
In message <MPG.23e1ac54aea487029896d4@172.16.0.1>, Paul Carpenter <paul@pcserviceselectronics.co.uk> writes>In article <hvu+9Khby1dJFARu@phaedsys.demon.co.uk>, chris@phaedsys.org >says... >> In message >> <8a411655-4c62-4490-9f21-8cd7835e32bb@z28g2000prd.googlegroups.com>, >> rickman <gnuarm@gmail.com> writes >> >The fact that you judge serial ports as being "legacy" does not mean >> >they shouldn't be used in new designs. Here is an excellent example >> >of why. Much GPS equipment has used RS-232 serial port for NMEA >> >compatible comms. There is no USB on the go equivalent. But many new >> >units are coming out with only a USB port. So this new equipment is >> >not compatible with applications requiring communications with other >> >GPS equipment, not because the other equipment is "old", but because >> >USB just won't work in this application. >> >> The problem depends on your application domain. 90% of MCU have serial >> port and any one can do serial comms in 10 minutes which both hands tied >> behind their back. >> >.. >> The problem is that many modern laptops don't have a serial port. Most >> desktop PC's still have one AFAIK but lots of USB so many consumer items >> have USB. > >About 6 months ago (maybe 9) one of my custoemrs deliberately bought a HP >laptop because it had a Serial port and XP.I did exactly the same because I needed a serial port.>> USB is not the easiest thing to just knock up from scratch in an >> embedded system. > >Agreed, how long before you need a 32 bit OS on temperature logger, just >so it can be connected via USB. If you are not careful you end up >with the > "[USB] tail wagging the dog [embedded system]"Many (most?) mcu , and certainly the smaller ones don't have USB on board. But the all have a serial port (or two)>> Also serial is universal and things like VT52 or VT100 you can almost do >> in your sleep for virtually any screen. >> >> If PC's drop the one serial port most AFAIK mother boards have then >> RS232 is not a good idea. But there is so much industrial use of RS232 >> that I doubt it will happen for a long time > >Half the rouble is some customers who I know who would rather bit bang >via USB from a PC to SPI devices, rather than have an onboard micro. >Basically because they believe they have lots of processor ticks on >a PC than on an embedded micro.Interesting. -- \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/ \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
Reply by ●January 22, 20092009-01-22
In article <sg4NenAMkCeJFA4h@phaedsys.demon.co.uk>, chris@phaedsys.org says...> In message <MPG.23e1ac54aea487029896d4@172.16.0.1>, Paul Carpenter > <paul@pcserviceselectronics.co.uk> writes > >In article <hvu+9Khby1dJFARu@phaedsys.demon.co.uk>, chris@phaedsys.org > >says... > >> In message > >> <8a411655-4c62-4490-9f21-8cd7835e32bb@z28g2000prd.googlegroups.com>, > >> rickman <gnuarm@gmail.com> writes > >> >The fact that you judge serial ports as being "legacy" does not mean > >> >they shouldn't be used in new designs. Here is an excellent example > >> >of why. Much GPS equipment has used RS-232 serial port for NMEA > >> >compatible comms. There is no USB on the go equivalent. But many new > >> >units are coming out with only a USB port. So this new equipment is > >> >not compatible with applications requiring communications with other > >> >GPS equipment, not because the other equipment is "old", but because > >> >USB just won't work in this application. > >> > >> The problem depends on your application domain. 90% of MCU have serial > >> port and any one can do serial comms in 10 minutes which both hands tied > >> behind their back. > >> > >.. > >> The problem is that many modern laptops don't have a serial port. Most > >> desktop PC's still have one AFAIK but lots of USB so many consumer items > >> have USB. > > > >About 6 months ago (maybe 9) one of my custoemrs deliberately bought a HP > >laptop because it had a Serial port and XP. > > I did exactly the same because I needed a serial port. > > >> USB is not the easiest thing to just knock up from scratch in an > >> embedded system. > > > >Agreed, how long before you need a 32 bit OS on temperature logger, just > >so it can be connected via USB. If you are not careful you end up > >with the > > "[USB] tail wagging the dog [embedded system]" > > > Many (most?) mcu , and certainly the smaller ones don't have USB on > board. But the all have a serial port (or two)I hate to burst your bubble---there are whole series of MCUs with no hardware serial interfaces. Take a look at the Microchip PIC10 and PIC12 series, for example. I'm sure other processor vendors have low-end chips with no serial interfaces also.> > >> Also serial is universal and things like VT52 or VT100 you can almost do > >> in your sleep for virtually any screen. > >> > >> If PC's drop the one serial port most AFAIK mother boards have then > >> RS232 is not a good idea. But there is so much industrial use of RS232 > >> that I doubt it will happen for a long timeYou can usually add a serial interface card to get RS-232 ports on desktop PCs. Sometimes it is just a matter of getting a connector for the onboard port the vendor hasn't bothered to bring out to the back panel. For laptops, you can add a PCMCIA serial port card.> > > >Half the rouble is some customers who I know who would rather bit bang > >via USB from a PC to SPI devices, rather than have an onboard micro. > >Basically because they believe they have lots of processor ticks on > >a PC than on an embedded micro. > > Interesting. >Mark Borgerson
Reply by ●January 22, 20092009-01-22
On Jan 22, 3:06=A0am, Chris H <ch...@phaedsys.org> wrote:> In message <MPG.23e1ac54aea48702989...@172.16.0.1>, Paul Carpenter > <p...@pcserviceselectronics.co.uk> writes > > > > >In article <hvu+9Khby1dJF...@phaedsys.demon.co.uk>, ch...@phaedsys.org > >says... > >> In message > >> <8a411655-4c62-4490-9f21-8cd7835e3...@z28g2000prd.googlegroups.com>, > >> rickman <gnu...@gmail.com> writes > >> >The fact that you judge serial ports as being "legacy" does not mean > >> >they shouldn't be used in new designs. =A0Here is an excellent exampl=e> >> >of why. =A0Much GPS equipment has used RS-232 serial port for NMEA > >> >compatible comms. =A0There is no USB on the go equivalent. =A0But man=y new> >> >units are coming out with only a USB port. =A0So this new equipment i=s> >> >not compatible with applications requiring communications with other > >> >GPS equipment, not because the other equipment is "old", but because > >> >USB just won't work in this application. > > >> The problem depends on your application domain. 90% of MCU have serial > >> port and any one can do serial comms in 10 minutes which both hands ti=ed> >> behind their back. > > >.. > >> The problem is that many modern laptops don't have a serial port. Most > >> desktop PC's still have one AFAIK but lots of USB so many consumer ite=ms> >> have USB. > > >About 6 months ago (maybe 9) one of my custoemrs deliberately bought a H=P> >laptop because it had a Serial port and XP. > > I did exactly the same because I needed a serial port.I'm curious, do you know how the serial port is implemented? It used to be that serial and parallel ports were in the South Bridge chip and so were free other than the cost of adding the transceiver chip and the connector. But those chips have gone by the wayside. Someone mentioned that a PCMCIA card they bought had a USB hub chip and two USB serial controllers that provided the same results as using two USB converters! I wonder if the laptops today do this as well. Rick
Reply by ●January 22, 20092009-01-22
On 2009-01-21, rickman <gnuarm@gmail.com> wrote:> On Jan 21, 2:47�pm, Cesar Rabak <csra...@bol.com.br> wrote: >> >> My opinion is that since it will be less likely new computers will come >> with serial ports, for *new* developments it is wiser to use an >> up-to-date comm solution. > > Yes, you keep repeating this and we have answered that. Computers > don't come with everything everyone needs and never will. Just as > most computers don't come with firewire, but it can be added, does not > mean it is a "legacy" interface that should be avoided. There are > many devices that work much better over firewire than they do USB.Personally I can see a role for RS-232 for new equipment that is expected to have an extremely long lifespan. Do you think that PCs in 25, 30 or 40 years time are going to have USB ports? They may do but it strikes me that there is a good chance (perhaps probable) that the world will have moved on to some new incompatible standard. At this point you are likely going to be stuck: USB requires a lot more (software) infrastructure to support it than RS-232 and if your future system doesn't have that support then USB is effectively no longer possible. On the other hand, you are always going to be able to support RS-232 becasue of its inherent simplicity. You may well need to hook up a serial card, or dongle or whatever but I can't imagine them totality disapearing within our lifetimes. Once the hardware is sorted the software may need some work to get it up on new hardware but the bulk of the system will remain intact. -- Andrew Smallshaw andrews@sdf.lonestar.org
Reply by ●January 22, 20092009-01-22
In message <MPG.23e244f8c37ac8929896ac@news.motzarella.org>, Mark Borgerson <mborgerson@comcast.net> writes>In article <sg4NenAMkCeJFA4h@phaedsys.demon.co.uk>, chris@phaedsys.org >says... >> Many (most?) mcu , and certainly the smaller ones don't have USB on >> board. But the all have a serial port (or two) > >I hate to burst your bubble---there are whole series of MCUs with no >hardware serial interfaces. Take a look at the Microchip PIC10 and >PIC12 series, for example.DO they have USB?> I'm sure other processor vendors have >low-end chips with no serial interfaces also.OK apart from a couple of Micro Chip Parts any others? I bet you will find vastly more have serial than have USB>You can usually add a serial interface card to get RS-232 ports on >desktop PCs. Sometimes it is just a matter of getting a connector >for the onboard port the vendor hasn't bothered to bring out to the >back panel.Quite so but> For laptops, you can add a PCMCIA serial port card.Sorry they are phasing out PCMCIA in favour of USB on a lot of them. This is a pity as PCMCIA is very useful -- \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\ \/\/\/\/\ Chris Hills Staffs England /\/\/\/\/ \/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/
Reply by ●January 22, 20092009-01-22
Chris H wrote:> Paul Carpenter <paul@pcserviceselectronics.co.uk> writes >> chris@phaedsys.org says... >>... snip ...>> >>> The problem is that many modern laptops don't have a serial >>> port. Most desktop PC's still have one AFAIK but lots of USB >>> so many consumer items have USB. >> >> About 6 months ago (maybe 9) one of my custoemrs deliberately >> bought a HP laptop because it had a Serial port and XP. > > I did exactly the same because I needed a serial port.And I bought a used IBM Thinkpad T30 for the same reason. -- [mail]: Chuck F (cbfalconer at maineline dot net) [page]: <http://cbfalconer.home.att.net> Try the download section.
