Using USB instead of RS232 on embeded project

Stephen Pelc wrote:

> On Thu, 23 Sep 2004 12:49:32 GMT, Art K6KFH
> <art_horne@phase4wireless.com> wrote:
> 
> 
>>I am developing a product that requires a serial port to transfer a
>>few bytes of data to a host pc on a repetitive basis.  Currently using
>>115kbaud on an RS232 port on my board and that works fine. A little
>>slower is ok  too.  Some feedback has indicated that a USB port would
>>be an attractive alternative.

Please don't stick with RS-232, you have to go USB.

Have a look at:
http://www.dontronics.com/cat_index_hard.html

for heaps of USB solutions, including the FTDI chips, and evaluation modules 
that will give you a kick start to your project.

3 years ago we sold a heap of PIC programmers that used either RS-232 or the 
parallel port. Today we only have USB, and they all use the FTDI chip.


Don...


-- 
Don McKenzie
E-Mail Contact Page:       http://www.e-dotcom.com/ecp.php?un=Dontronics

Free phone calls via USB Phone:  http://www.dontronics.com/usbphone.html
USB to RS232 Converter that works http://www.dontronics.com/usb_232.html

Meindert Sprang wrote:
> "Phil W" <electropw@hotmail.com> wrote in message
> news:41535638@dnews.tpgi.com.au...
> 
>>Art,
>>
>>If you already have it going why change?
> 
> Well, because of laptops with no serial ports?
> 
>>Moving to USB is not a simple step and by the sound of it would achieve
>>little.
> 
> With the chips from FTDI is IS a simple step.
> If you just want to replace a serial connection with USB, the FTDI chips let
> you do it within hours.
> 
> Meindert

I agree, Phil appears pessimistic. But there are solid reasons for 
keeping a product RS232, such as cost and interoperability (eg modems / 
printers / other dumb devices), not to mention "ain't broke". Companies 
like easysync.co.uk - using FTDI - are fixing the laptop problem, so why 
change unless it's a hard marketing requirement?

Cheers,
Mike.

-- 
Mike Page BEng(Hons) MIEE           www.eclectic-web.co.uk
Quiet! Tony's battling the forces of conservatism, whoever we are.

On Friday, in article
     <OtKdnURxgbvCkcncRVn-uQ@eclipse.net.uk>
     mike@SCRUBeclectic-CAPSweb.BLAMEco.SWENuk "Mike Page" wrote:
>Meindert Sprang wrote:
>> "Phil W" <electropw@hotmail.com> wrote in message
>> news:41535638@dnews.tpgi.com.au...
>> 
>>>Art,
>>>
>>>If you already have it going why change?
>> 
>> Well, because of laptops with no serial ports?
>> 
>>>Moving to USB is not a simple step and by the sound of it would achieve
>>>little.
>> 
>> With the chips from FTDI is IS a simple step.
>> If you just want to replace a serial connection with USB, the FTDI chips let
>> you do it within hours.

For quite a few applications where the RS232 connection is used infrequently
(e.g. site visits to examine logs, update software), a special RS232 to
USB cable keeps the design changes and field types to a minimum.

>> Meindert
>
>I agree, Phil appears pessimistic. But there are solid reasons for 
>keeping a product RS232, such as cost and interoperability (eg modems / 
>printers / other dumb devices), not to mention "ain't broke". Companies

Not to mention, implementing RS232 on many devices is simple and cheap
(cost and system overhead). Whereas an external RS232 to USB for many
applications is all that is required, especially on lots of projects where
the use is infrequent.
 
>like easysync.co.uk - using FTDI - are fixing the laptop problem, so why 
>change unless it's a hard marketing requirement?
                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
Should read "follow the current desktop fad".

I wonder how many have had requests to wireless network their current projects
because it would be nice, despite the overkill for many applications.

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info
<http://www.badweb.org.uk/>             For those web sites you hate

"Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote in
news:10l7h62csreclf0@corp.supernews.com: 

> If you just want to replace a serial connection with USB, the FTDI
> chips let you do it within hours.

Not necessarily.  We have a product that uses RS232 as a configuration and 
data collection port.  We have a consderable investment in Palm OS software 
to do this configuration and data collection, but more and more Palm OS 
devices are being shipped with no RS232 available, instead using USB.  We 
can't use USB to RS232 converters, because the Palm is a USB peripheral, 
not a USB controller.  The FTDI chip is absolutely useless in this 
scenario.  I'm still not sure what we will do when the serial ports on 
Palms finally go away.

Jeff.

"Paul Carpenter" <paul$@pcserv.demon.co.uk> wrote
>
>>like easysync.co.uk - using FTDI - are fixing the laptop problem, so why
>>change unless it's a hard marketing requirement?
>                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
> Should read "follow the current desktop fad".

Finding laptops with a serial port has always been difficult, much less 
finding a laptop with two serial ports if that's what you need. Multiple 
serial ports have always been a problem with desktops, too, if you need more 
than the two that come with the machine. (I'm speaking of situations where 
people used to need multiple serial-based products on their machines in 
commercial and industrial applications, not hobbyist setups or VAR systems.)

Now, there is USB. Virtually all computers have it, and have had for at 
least a few years now. Need to hook up more stuff? No problem, get a hub. 
You can even pull power from the USB port, not much, but its there and a lot 
of times you can use it.

Hey, I miss serial communications too. It was easy to deal with, even in 
asm. USB definitely ads a level of complexity. But times have changed, and 
USB is superior to serial for many different types applications.

> I wonder how many have had requests to wireless network their current 
> projects
> because it would be nice, despite the overkill for many applications.

Overkill, by who's definition?

Mike 

If everyone will pardon the thread stealing I'd like to find out the
same thing but with Linux drivers or at least examples. I'm seeing
more and more devices come out with USB (I hate USB) and it's time
that I start to learn how to write for USB & Linux. I know about the
FTDI chip (looks like a serial, cool!) but I may eventually need to
support other USB chips that are not so nice. Thanks

-- 
Linux Home Automation         Neil Cherry        ncherry@comcast.net
http://home.comcast.net/~ncherry/               (Text only)
http://hcs.sourceforge.net/                     (HCS II)
http://linuxha.blogspot.com/                    My HA Blog

On Friday, in article <ocX4d.356878$sh.333765@fed1read06>
     miketurco@yahoo-nospam4me.com "Mike Turco" wrote:

>"Paul Carpenter" <paul$@pcserv.demon.co.uk> wrote
>>
>>>like easysync.co.uk - using FTDI - are fixing the laptop problem, so why
>>>change unless it's a hard marketing requirement?
>>                      ^^^^^^^^^^^^^^^^^^^^^^^^^^
>> Should read "follow the current desktop fad".
>
>Finding laptops with a serial port has always been difficult, much less 
>finding a laptop with two serial ports if that's what you need. Multiple

PCMCIA or USB to RS232 exist and have existed for some time.
 
>serial ports have always been a problem with desktops, too, if you need more

Multiple port PCI cards and before that ISA cards have existed and are
still available.
 
>than the two that come with the machine. (I'm speaking of situations where 
>people used to need multiple serial-based products on their machines in 
>commercial and industrial applications, not hobbyist setups or VAR systems.)

So am I, even years before the PC, industrial applications often had add in
cards of multiple serial ports.

>Now, there is USB. Virtually all computers have it, and have had for at 
>least a few years now. Need to hook up more stuff? No problem, get a hub. 
>You can even pull power from the USB port, not much, but its there and a lot 
>of times you can use it.
>
>Hey, I miss serial communications too. It was easy to deal with, even in 
>asm. USB definitely ads a level of complexity. But times have changed, and 
>USB is superior to serial for many different types applications.

Now you are in the realms of long term support and conflicts beyond your
control. Having seen too many badly written pieces of USB devices that mean
you are potentially sharing a communications channel with soemthing beyond
your control.

Let's see well known brand of scanners that added the following levels
of software as their scanners kept up with the latest fad and they did
a major kludge on their software. The device started as a SCSI device,
became parallel port, then USB, so we ended up with the following drivers

        SCSI pseudo device
          &#4294967295;
          --- Parallel port to SCSI driver
                &#4294967295;
                ------ USB to parallel driver
                        &#4294967295;
                        ---- various USB drivers to talk to the device

The customer sites I have been to where the systems had to have the multi
interface devices connected by means other than USB, as the USB devices
and their software interacted with each other causing crashes or other
instability.

Most of the host side software, like most windows applications assumes
it is the ONLY thing added to a virgin system.

Plug and play is NOT that, but load the software BEFORE connecting the
device. Then make sure you have either shut the machine down or used
"Safely remove Hardware", before disconnecting. The number of people
who I have seen caught out by these is beyond belief.

Then the support nightmares of hardware or operating system upgrades
and there is no longer support for devices. I have seen this already
for USB devices, because the toy market called desktops/laptops assumes
at the slightest problem everything is ditched for the new model.

USB is NOT mature on the software front for me to consider for many
applications, either due to burst communications or random connections
like once a month.

There are PC type applications where USB like interfacing would be a good
idea (cameras, scanners, temporary media connections), but too much is
done on it relying on using up the host resources to do what should be
done in the device. Classic example being inkjet printers.

For PC applications not involving Games, typewriting, web browsing and
other toy usages, USB adds too many non deterministic features to make
it worthwhile.

>> I wonder how many have had requests to wireless network their current
>> projects
>> because it would be nice, despite the overkill for many applications.
>
>Overkill, by who's definition?

There are many applications, where the environment will mean it is not
practical. Excessive addition of cost and/or power consumption for the
amount of benefit. Let alone the complexity of adding to quite a few
applications a 16/32bit processor module to do the work of the wirless
link on an application that is 4/8 bit in the first place.

If you want to have PC fad, make the system from a PC in the first place.

More often the things are added because they can or it is the latest fad
e.g. Bluetooth, or internet access (e.g. washing machines, pens and toaster
that have internet connections).

I have seen too many projects that used a PC that should have been a black
box that was a 100baseT interface for the archiving of data, that have
caused long term support and manufacturing problems due to inability
to get the same PC three months later, let alone the software and
interface cards issues.

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info
<http://www.badweb.org.uk/>             For those web sites you hate

>Take a look at http://www.ftdichip.com/

For low-volume designers/manufacturers, a big reason to use FTDIChip
is the ability to use their VID, which will save you $1500 the last
time I checked:

http://www.dlpdesign.com/usb/vid.html

I have an article about using FTDI's USB UART here:

http://www.lvr.com/boardusb.htm

Jan Axelson
www.Lvr.com

>. I'm seeing
>more and more devices come out with USB (I hate USB) and it's time
>that I start to learn how to write for USB & Linux.

I have links to Linux USB info here, under Non-Windows hosts:

http://www.lvr.com/usb.htm#HostSoftware

and here:

http://www.lvr.com/hidpage.htm#hostprogramming

Jan Axelson
www.Lvr.com

Jeffrey A. Wormsley wrote:

> "Meindert Sprang" <mhsprang@NOcustomSPAMware.nl> wrote in
> news:10l7h62csreclf0@corp.supernews.com: 
> 
> 
>>If you just want to replace a serial connection with USB, the FTDI
>>chips let you do it within hours.
> 
> 
> Not necessarily.  We have a product that uses RS232 as a configuration and 
> data collection port.  We have a consderable investment in Palm OS software 
> to do this configuration and data collection, but more and more Palm OS 
> devices are being shipped with no RS232 available, instead using USB.  We 
> can't use USB to RS232 converters, because the Palm is a USB peripheral, 
> not a USB controller.  The FTDI chip is absolutely useless in this 

AT43USB380 is a host.




> scenario.  I'm still not sure what we will do when the serial ports on 
> Palms finally go away.
> 
> Jeff.