Date: Tue, 20 Dec 2016 14:26:20 -0500 From: George Mitchell <george+freebsd@m5p.com> To: Ian Lepore <ian@freebsd.org>, freebsd-hackers@freebsd.org Subject: Re: USB ppbus? Message-ID: <7cd409d4-cb49-6384-180b-51e58ca54a66@m5p.com> In-Reply-To: <1482259297.48539.30.camel@freebsd.org> References: <35e62a59-556a-68bf-3b9d-017108f12f38@m5p.com> <930e14f6-d8a8-7f50-21b4-6e76c2057f31@selasky.org> <c34b2afa-8123-80ce-a925-856b0bfe8621@m5p.com> <1482259297.48539.30.camel@freebsd.org>
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On 12/20/16 13:41, Ian Lepore wrote: > On Tue, 2016-12-20 at 13:15 -0500, George Mitchell wrote: >> [...] >> Thanks for the response. I think I could kludge the ioctls I want >> into >> ulpt.c by learning more about the USB system works. Possibly. On a >> good day. -- >> George >> > > IMO, ppbus solves a 1990s problem that we don't much have anymore: > multiplexing multiple concurrent (or time-slice-shared) users of a > single parallel port that may have multiple non-printer devices daisy- > chained on it. > > If the only thing you're looking for is the ability to treat some of > the DB25 pins as gpio pins, just adding the ioctls to ulpt.c might be > the way to go. > > Another possiblity, if all you're after is gpio on the end of a usb > wire, is to use an FTDI usb-serial adapter and then use either the > existing ioctl() interface in the uftdi driver (see uftdi(4) manpage), > or libusb and libftdi (I'm not sure the latter has ever been ported to > freebsd). > > -- Ian > [...] Thanks. I need the DB25 Centronics interface on the end of a USB wire, so I guess I'll learn more about the USB system. Musing: Has any other presently defunct company exerted such an influence on computer interfacing over the years than Centronics Data Computer Corporation? (Yes, I know they defined the 36-pin "blue ribbon" interface, and that IBM promulgated the DB25 connector for it, but electrically it was the Centronics interface.) -- George
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