Date: Sun, 14 Apr 1996 19:47:41 +0300 (EET DST) From: dk@clipper.cs.kiev.ua (Dmitry Kohmanyuk) To: freebsd-hardware@freebsd.org Subject: building parallel interface gadget - advice wanted Message-ID: <199604141647.TAA08085@clipper.cs.kiev.ua>
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hi gang, I am building (together with a electronics engineer) a device which, when attached to parallel potr, would perform some useful functions for my FreeBSD machines and maybe other devices connected to it. I have thoroughly read all the specs I have get a hold of and an entire lpt.c / lptreg.h in FreeBSD kernel. My only question is: from my understanding, for the data byte t obe output into the (real) printer, it is necessary to assert select, !initialize and strobe bits of control register and then lower the signal on the strobe pin, leaving select and !initialize high. Can it be possible that the same situation unwantedly occurs during system reset (power-on, reset by switch, software-executed reboot, etc.)? We try to follow printer's interface in using the potr to enable general-purpose hardware drivers to operate the device. I therefore want to make sure that by no circumstances a random data would be mistakenly read and accepted, causing unexpected behaviour of the device. thank anyone for reading this. p.s. if you are curious about the device itself, it would implement watchdog timers, power switches, etc. And I am not a company ;-) (we would make only one, or two for ourselves.)
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