Sorry about that, it seems my site suffers from sever link rot,,, try http://www.ultranet.com/~jason/mchip.shtml for my 20x4 LCD code with 4 push buttons..... I'm registering a domain name now and I promise to fix my page............. -----Original Message----- From: Gordon Zerf To: PICLIST@MITVMA.MIT.EDU Date: Thursday, October 30, 1997 6:08 AM Subject: Re: A stupid question but... >I have a similar problem, using a 4x20 and had a look at the site, but >found no code to look at > >Gordon > > >At 09:30 30/10/97 -0000, you wrote: >>Nice one thanks. >> >>I'm still a little confused as to how to deal with the situation where >>the switches are NOT enabled (ie common portion floating) and you are >>accessing the LCD when TWO or more switches are pressed. Surely this >>will short two data lines together and invalidate the data to/from the >>LCD ? >> >>Please excuse my ignorance on this - it is my first (very ambitious) PIC >>project. >> >> \\\|/// >> \\ - - // "Yes it IS safe >> ( @ @ ) to switch on" >>+---oOOo-(_)-oOOo------------------+ >>| Mark Birks | >>| Hardware Section Leader | >>| OmniBus Systems, Stanford House, | >>| Stanford-on-Soar, | >>| Loughborough, Leicestershire. UK.| >>| | >>| Tel/Fax: +44 (0)990 004300/333 | >>| E-Mail: markb@omnibus.co.uk | >>| ooo0 | >>| ( ) 0ooo | >>+---\ (----( )------------------+ >> \_) ) / >> (_/ >> >> >>> ---------- >>> From: Jason Wolfson[SMTP:jason@MA.ULTRANET.COM] >>> Reply To: pic microcontroller discussion list >>> Sent: 29 October 1997 18:42 >>> To: PICLIST@MITVMA.MIT.EDU >>> Subject: Re: A stupid question but... >>> >>> Mark, >>> I did this with a 20x4 LCD and it worked great, >>> check out my code at http://www.ultranet.com/~jason >>> >>> I put the 4 buttons at each corner of the display and you >>> put up a message to their function depending on what you want when... >>> Kinda like an ATM machine.... >>> >>> Jason >>> >>> >>> >>> -----Original Message----- >>> From: Mark Birks >>> To: PICLIST@MITVMA.MIT.EDU >>> Date: Wednesday, October 29, 1997 12:04 PM >>> Subject: A stupid question but... >>> >>> >>> >Is it possible to multiplex the scanning of 4 push-button switches on >>> >the same 4 'data' lines as an LCD module is using ? >>> > >>> >I've sort of thought along the lines of having all of the switches >>> >commoned at one side and then having an OPen -collector arrangement >>> to >>> >short the switches to ground at read time. >>> > >>> >The drawback with this arrangement is that when the switches are NOT >>> >being read and one or more switches are closed, data lines will be >>> >shorted together. Adding diodes seemed like an obvious step forward >>> but >>> >the 0.7V drop takes them to the top end of the TTL logic '0' level. >>> > >>> >Anyone got any suggestions please ? >>> > >>> >Also I am looking at using a standard 16x2 LCD with these switches to >>> >allow menu selection and configuration settings - has anyone done >>> >anything that allows the PIC to communicate with a host processor (in >>> >this case it is ACORN podule bus) to download menu choices, >>> selections >>> >etc. I am trying to reduce the amount of processing done by the host >>> so >>> >that the PIC can deal with most of the menu control if poss........ >>> > >>> > \\\|/// >>> > \\ - - // "Yes it IS safe >>> > ( @ @ ) to switch on" >>> >+---oOOo-(_)-oOOo------------------+ >>> >| Mark Birks | >>> >| Hardware Section Leader | >>> >| OmniBus Systems, Stanford House, | >>> >| Stanford-on-Soar, | >>> >| Loughborough, Leicestershire. UK.| >>> >| | >>> >| Tel/Fax: +44 (0)990 004300/333 | >>> >| E-Mail: markb@omnibus.co.uk | >>> >| ooo0 | >>> >| ( ) 0ooo | >>> >+---\ (----( )------------------+ >>> > \_) ) / >>> > (_/ >>> > >>> >> >> >