I did a project for Brian Kraut where we used a 16F877 to control a single backplane LCD module. The module is a large 4 digit 7 segment plus decimal point unit. I created the necessary 50.0% AC waveform using an interrupt driven routine. I also did a multi-backplane LCD module that used an 16C74. The multi-backplane LCDs used less I/O pins, but required a bit more at the software end. Using an interrupt driven routine to do the timing for the LCD segments helps to keep the AC waveforms operating at the desired 50.0% If the waveforms are off by more than a fraction of a percent, then the thin film electrode structure gets detroyed over time and the display would wash out. As it is, we managed to get a really great contrast level, with a deep black that is very easy to read. This is with the +5 volt max signal level. Fr. Thomas McGahee ----- Original Message ----- From: Friedel Bruening To: Sent: Friday, November 16, 2001 9:57 PM Subject: Re: [PIC]: Simple Question on driving 7 segment display with PIC Will be difficult, there is not appropiate hardware on a 16F877 to drive this kind LCD, there are other PIC4s which I am not familiar with to do that. You need dedicated pin drivers for LCD, they work with kind AC signals. Friedel At 11:00 p.m. 16/11/01 +0200, you wrote: >You can make a a 16F877 drive a bare LCD module with 3 1/2 digits designed >for use with ICL7106 DVMs. These were available in small qty. from mail >order places last time I looked (years ago). You will need ~15 IO pins to >drive it (afair). Use a single driver on the backplane (the pin fan out is >not enough) and make sure that the duty cycle is 50.0% or the display will >be destroyed within weeks. The contrast at 5V is not so wonderful but it >works at room temp. > >Peter > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads