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USB to parallel

M

Marco Trapanese

Jan 1, 1970
0
Hi to all,

I'm looking for a chip to use a virtual parallel port through an USB
connection. For example FTDI makes FT232* ICs for RS232 serial ports. I
need something like that but for parallel ports.

Of course, third parts applications should run fine either with physical
or virtual parallel ports.

May you point out me any chip?

Thanks
Marco
 
R

Rich Webb

Jan 1, 1970
0
Hi to all,

I'm looking for a chip to use a virtual parallel port through an USB
connection. For example FTDI makes FT232* ICs for RS232 serial ports. I
need something like that but for parallel ports.

Of course, third parts applications should run fine either with physical
or virtual parallel ports.

A legacy application (not a simple parallel printer) that assumed that
it was interfaced to a genuine hardware parallel port at 0x378 will
almost certainly not work with a USB connection in the middle. Things
like parallel port based device programmers don't translate well to an
intermediate packet based layer.

It might be possible to come up with a way to fool a particular
application into running over a USB-parallel port. Designing an adapter
that supported all third party applications (which will include some
that were written back in the days of MS-DOS and 5 1/4" floppies) is ...
challenging.
 
M

Marco Trapanese

Jan 1, 1970
0
Rich Webb ha scritto:
A legacy application (not a simple parallel printer) that assumed that
it was interfaced to a genuine hardware parallel port at 0x378 will
almost certainly not work with a USB connection in the middle. Things
like parallel port based device programmers don't translate well to an
intermediate packet based layer.

It might be possible to come up with a way to fool a particular
application into running over a USB-parallel port. Designing an adapter
that supported all third party applications (which will include some
that were written back in the days of MS-DOS and 5 1/4" floppies) is ...
challenging.



Ok, thank you very much for your answer. Furthermore, the main
application should be a stepper motor driver: I bet the USB device can't
handle the clock rate as accurate as the hardware parallel port can.

Marco
 
A

Archimedes' Lever

Jan 1, 1970
0
Rich Webb ha scritto:




Ok, thank you very much for your answer. Furthermore, the main
application should be a stepper motor driver: I bet the USB device can't
handle the clock rate as accurate as the hardware parallel port can.

Marco

What part of a USB port is not hardware? Also, one could easily write
the stepper motor app and design the I/O interface such that no
difference could be detected.
 
M

Marco Trapanese

Jan 1, 1970
0
Archimedes' Lever ha scritto:
What part of a USB port is not hardware?


I'm talking about the USB protocol.

Also, one could easily write
the stepper motor app and design the I/O interface such that no
difference could be detected.


Of course. But I need to interface existing apps.

Marco
 
A

Allan Herriman

Jan 1, 1970
0
Hi to all,

I'm looking for a chip to use a virtual parallel port through an USB
connection. For example FTDI makes FT232* ICs for RS232 serial ports. I
need something like that but for parallel ports.

Of course, third parts applications should run fine either with physical
or virtual parallel ports.

May you point out me any chip?

FTDI also make FT245* devices that have a parallel interface (no, it's
not exactly equivalent to a PC parallel port (IEEE 1284) but it does give
you the ability to bit-bash several I/O lines). Their newer devices,
e.g. FT2232D, can be run in a number of modes, allowing them to emulate
both the '245 and the '232 parts.

The very newest FTDI parts, e.g. FT2232H, use USB2.0 which might allay
some of your timing concerns.

Regards,
Allan
 
R

Rich Webb

Jan 1, 1970
0
Rich Webb ha scritto:




Ok, thank you very much for your answer. Furthermore, the main
application should be a stepper motor driver: I bet the USB device can't
handle the clock rate as accurate as the hardware parallel port can.

For a given application it may be possible to implement a USB solution,
particularly if you're comfortable with sticking a microcontroller "in
the middle" to handle the low-level timing issues. That still may not
fly if the host application on the PC side expects to have well-defined
command/response cycles on the I/O lines.

An option may be to try a PCMCIA parallel port. These could be (note:
not all are) identical to a legacy hardware port. Or an expansion card,
if you're running a desktop or PC/104 unit.
 
M

Marco Trapanese

Jan 1, 1970
0
Rich Webb ha scritto:
For a given application it may be possible to implement a USB solution,
particularly if you're comfortable with sticking a microcontroller "in
the middle" to handle the low-level timing issues. That still may not
fly if the host application on the PC side expects to have well-defined
command/response cycles on the I/O lines.

An option may be to try a PCMCIA parallel port. These could be (note:
not all are) identical to a legacy hardware port. Or an expansion card,
if you're running a desktop or PC/104 unit.


Thank you again.
Marco
 
J

Jasen Betts

Jan 1, 1970
0
Ok, thank you very much for your answer. Furthermore, the main
application should be a stepper motor driver: I bet the USB device can't
handle the clock rate as accurate as the hardware parallel port can.

if you can put the USB in isochronous mode it will do it better than a
hardware parallel port can.
 
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