Jim, thanks for your answer. What I would like to do is to manipulate the pins of a DDS on an external board, which are connected to the pins of the parallel port. The protocol is with two wires (clock and data), serial. You have to send out 40 bits to change the value of the Frequency Tuning Word to set a new frequency. With a real parallel port it works beautifully, I am able to scan frequencies even at 20 new values per second (I don't need more, so stopped here, but maybe it is possible to go higher). My concern is that I would like that this program could run also on laptops without a real parallel port, making use of a USB<->Parallel converter.
I use a third-party kernel driver that allows me to do physical I/O even from Windows XP, and was convinced that those converters came with a device driver that fully emulated the parallel port, up to the point of being able to do direct I/O to the pins. Apparently I was wrong, unless some brands and/or models of those converters behave like that. If someone has suggestions, please don't be shy... :-) 73 Alberto I2PHD ---------------------------- Jim Lux wrote: > At 10:03 AM 8/10/2006, Alberto I2PHD wrote: >> Please excuse me for this OT request, but I think that in this group there >> are a few who have played with the USB to >> Parallel converters, generally in form of a cable (with some chips in the >> connector shell). >> >> Are they good for a printer exclusively, or can I drive the single pins of >> the parallel port, not only the 8 data bits, >> but e.g. the Strobe pin, the AutoFeed pin, the Initialize pin, etc. and in >> the reverse direction, can I read the Busy >> pin, the PaperEnd pin, the Select pin, etc. ? > > > Not usually.. they don't show up as a i/o device... You talk to it through > some form of software driver, which may or may not implement all the IOCTL > kinds of functinos. > > > >> In other words, loading the device driver that I suppose comes with the >> adapter, will my user program be able to do I/O >> on the 0x278, 0x279, 0x27a addresses (in case of LPT1), as when a real >> parallel port is present ? > > > There are some drivers out there that "emulate" a physical I/O port > (because the processor hardware allows a reference to a protected memory > space to generate an interrupt, you can do this) > > >> If someone has direct experiences on this, I would like hear from him, >> many thanks indeed. > > > I have had very poor luck using software that "talks directly to the > hardware" with non-standard hardware implementations. I'd try to figure > out how to do it with standard i/o device driver calls. > > I think the standard printer driver has enough smarts to do this > (certainly, it can do the outputs, the question is reading back all of the > status bits, or reading back data on the output bits) > > >> 73 Alberto I2PHD _______________________________________________ FlexRadio mailing list [email protected] http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archive Link: http://www.mail-archive.com/flexradio%40flex-radio.biz/ FlexRadio Homepage: http://www.flex-radio.com
