Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!usc!wuarchive!udel!haven!adm!cmcl2!uupsi!sunic!news.funet.fi!funic!santra!santra!tengdahl From: tengdahl@niksula.hut.fi (Tomi Holger Engdahl) Newsgroups: sci.electronics Subject: Re: A/D converter ==> PC parallel port? Message-ID: Date: 13 Dec 90 11:52:41 GMT References: Sender: news@santra.uucp (Cnews - USENET news system) Distribution: sci.electronics Organization: Helsinki University of Technology, Finland Lines: 49 In-Reply-To: billq@ms.uky.edu's message of 12 Dec 90 18:09:54 GMT In article billq@ms.uky.edu (fill in blank) writes: I am trying to use my PC(XT)'s paralle port to read the 8-bits information from the chip. I have had some luck reading in from the OUTPUT lines on the parallel port (i.e. I am breaking some rules ... I guess Maybe you are braking some rules but I have not noticed that this causes any damage to hardware. Parallel port (in most PC machines) can withstand those short circuits. But this is not working perfectly yet. I am using transisitors to drive the port (letting the A/D drive the transistors as switches, then use these to I have used 74LS245 chip to drive those OUTPUT lines succesfully. It has has worked without any problems. drive the tri-state parallel port). Its acting like when it see more then 4 or 5 0 bits, well ... it starts messing up, like maybe its drawing too much current or somthing? There is some kind of current limiting system in the parallel port. I have measured that the parallel port in my AT can supply about 40mA when short circuited tp ground. Any body beed doen this road before? Any body got a better way of designing an A/D ==> pc system? I have designed an A/D system to PC using ADC0809 A/D converter. It uses the parallel port output lines as input for 8 bit data. My system can make about 22 000 conversions / second, because I have boosted ADC0809 by using clock frequency of over 2 MHz. I have used this circuit for about 1/2 years for sampling audio signals. I have my information in computer format: text and GIF pictures. Unfortunately it is not available in any ftp site. It has only been downloadable in some BBSs here in Finland. Please e-mail if interrested in getting more information. -- ------ / / /--- --------------------------------- / /--/ /-- ! Mail: Tomi Engdahl ! / / / /--- ! Kalliom{entie 8bF ! E-mail: tengdahl@niksula.hut.fi ! 01800 Klaukkala, Finland ! tengdahl@otax.tky.hut.fi --------------------------------- d39060t@puukko.hut.fi Helsinki University of Technology