Post by thread:PIC 16c84 4bit LCD interface

After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x 16 LCD display I desperately seek some help. I tried to use the code snippet Dave Duley posted some time ago. Unfortunately it just did not work. Perhaps I failed, because the source covered only the used functions and no main program... The Microchip AN 587 example code uses a 16c5x device. As the only Pic Controller I have here is a 16c84 I ran into serious problems because i do not know all the registers and ports they use. I am not sure in what order I should connect the RB lines to the Display and if I should use rb0-rb3 or rb4-rb7 as data lines. I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8 bit interface without usage of the LCD R/W line. Thanks for any help Ralf

:After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x :16 LCD display I desperately seek some help. <etc...> If you do not mind doing some actual coding yourself, the thing you need is HD44780 manual. Now, fortunately, it is online. In http://www.hea.com/hean2/lcdc/hd44780list.htm at Hyundai pages you can find a rather complete manual for HD44780. Notice the initilaization procedure, you need at the beginning. You need that to set the 4-bit operating mode! For 4-bit interface you need 7 lines: Enable, Register Select, Red/Write and Data lines 4-7. Initiation of the 4-bit mode is described in the "Initialization: By Instructions" link and 8-bit data is written over the 4-bit interface with most significant nibble first. -- Lauri --- <a href="http://www.ee.oulu.fi/~lapi/">For more info.</a>

Ralf, see my test circuit and software for the 16C84 on http://ourworld.compuserve.com/homepages/steve_lawther/charlcd.htm This shows how to implement a 4 bit interface, and the test software gives you error codes, if it finds faults. Any problems, just shout. Steve Lawther ______________________________ Reply Separator _________________________________ Subject: PIC 16c84 4bit LCD interface - I need help Author: MIME:spam_OUTralf.sigmundTakeThisOuTSTUD.UNI-HANNOVER.DE at INTERNET-HUSKY Date: 26/02/98 14:56 After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x 16 LCD display I desperately seek some help. I tried to use the code snippet Dave Duley posted some time ago. Unfortunately it just did not work. Perhaps I failed, because the source covered only the used functions and no main program... The Microchip AN 587 example code uses a 16c5x device. As the only Pic Controller I have here is a 16c84 I ran into serious problems because i do not know all the registers and ports they use. I am not sure in what order I should connect the RB lines to the Display and if I should use rb0-rb3 or rb4-rb7 as data lines. I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8 bit interface without usage of the LCD R/W line. Thanks for any help Ralf

In message <.....199802261345.PAA13729KILLspam@spam@tk8.oulu.fi> PICLISTKILLspamMITVMA.MIT.EDU writes: {Quote hidden}> :After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x > :16 LCD display I desperately seek some help. > <etc...> > > If you do not mind doing some actual coding yourself, the thing you > need is HD44780 manual. Now, fortunately, it is online. In > > http://www.hea.com/hean2/lcdc/hd44780list.htm > > at Hyundai pages you can find a rather complete manual for HD44780. > Notice the initilaization procedure, you need at the beginning. > You need that to set the 4-bit operating mode! > > For 4-bit interface you need 7 lines: Enable, Register Select, > Red/Write and Data lines 4-7. Initiation of the 4-bit mode > is described in the "Initialization: By Instructions" link > and 8-bit data is written over the 4-bit interface with > most significant nibble first. > > -- Lauri Minor correction, I think you'll find the Read?write line is not needed and should be tied low IF you don't want to read from the display. Regards, Mike

Hi Ralf, I am just beginning to tackle the same project, interfacing a PIC to a HD44780 using the 4 bit interface. I am using a 74HC595 to free up some I/O on the PIC. Anyways, you are supposed to use DB4 to DB7. B.G. Micro sells some 2x20 LCD displays and their datasheet for the display has some helpful info about the 4bit transfer. Their website is http://www.bgmicro.com. I could also send the file if you like... Regards, Adi {Quote hidden}> Date: Thu, 26 Feb 1998 13:29:28 +0100 > Reply-to: Ralf Sigmund <.....ralf.sigmundKILLspam.....stud.uni-hannover.de> > From: Ralf Sigmund <EraseMEralf.sigmundspam_OUTTakeThisOuTSTUD.UNI-HANNOVER.DE> > Subject: PIC 16c84 4bit LCD interface - I need help > To: PICLISTspam_OUTMITVMA.MIT.EDU > After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x > 16 LCD display I desperately seek some help. > I tried to use the code snippet Dave Duley posted some time ago. > Unfortunately it just did not work. > Perhaps I failed, because the source covered only the used functions and no > main program... > The Microchip AN 587 example code uses a 16c5x device. > As the only Pic Controller I have here is a 16c84 I ran into serious > problems > because i do not know all the registers and ports they use. > I am not sure in what order I should connect the RB lines to the Display and > if I should use rb0-rb3 or rb4-rb7 as data lines. > I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8 > bit interface without usage of the LCD R/W line. > > Thanks for any help > Ralf >

Ralf, if you want to used the HD44780 in a 4 bit interface: 1.- You have to used DB4-DB7 in the module it doesnt matter if you conect rb0-rb3 or rb4-rb7 but you have to be wiser in what way you are sending the information. 2.- When you circuit startup wait at least 15ms before send any inormation to the HD44780. 3.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF 4.-Wait at least 5ms. 5.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF 6.- Wait at least 100uS. 7.- Put RS=0; R/W=0; dato=0011 (dato=DB7 DB6 DB5 DB4). dont check BF 8.- Put RS=0; R/W=0; dato=0010 (dato=DB7 DB6 DB5 DB4). this set 4 bit interface. after this step you can check BF and have to send the commands for funtion sets, etc. Ralf Sigmund escribis: {Quote hidden}> After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x > 16 LCD display I desperately seek some help. > I tried to use the code snippet Dave Duley posted some time ago. > Unfortunately it just did not work. > Perhaps I failed, because the source covered only the used functions and no > main program... > The Microchip AN 587 example code uses a 16c5x device. > As the only Pic Controller I have here is a 16c84 I ran into serious > problems > because i do not know all the registers and ports they use. > I am not sure in what order I should connect the RB lines to the Display and > if I should use rb0-rb3 or rb4-rb7 as data lines. > I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8 > bit interface without usage of the LCD R/W line. > > Thanks for any help > Ralf

At 13:29 26/02/98 +0100, you wrote: >After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x >16 LCD display I desperately seek some help. >I tried to use the code snippet Dave Duley posted some time ago. >Unfortunately it just did not work. >Perhaps I failed, because the source covered only the used functions and no >main program... UMPS will help you to see why it does not work: it will simulate the HC44780 LCD panel. Try it: http://www.sistudio.com/umps Regards, Philippe. +--------------------------------------------------------+ | Virtual Micro Design | | Technopole Izarbel, | | 64210 BIDART | | FRANCE | | | | Phone: +33 559.438.458 Fax: +33 559.438.401 | | | | E-Mail: @spam@p.techerKILLspamidls.izarbel.tm.fr | | URL: http://www.sistudio.com/umps | +--------------------------------------------------------+ {Quote hidden}>The Microchip AN 587 example code uses a 16c5x device. >As the only Pic Controller I have here is a 16c84 I ran into serious >problems >because i do not know all the registers and ports they use. >I am not sure in what order I should connect the RB lines to the Display and >if I should use rb0-rb3 or rb4-rb7 as data lines. >I tried Myke Predkos Thermo5 Basic Example which worked fine, but is an 8 >bit interface without usage of the LCD R/W line. > >Thanks for any help >Ralf > >

Ralf and Others I started a project some time ago which included the requirement for a 2-line lcd display using a 4 line interface to a 16X84. Others on the piclist helped me over a problem when I was setting the contrast incorrectly (in fact not at all). The lcd module is now working well and uses just 75 bytes (here a byte is 12 bits!). For those who want to look at yet another lcd driver, it's on my web page at http://www.shm.monash.edu.au/~r.kreymborg/pic/lcd.html and includes a test program and all the necessary files in zip format to download. Ron On Thu, 26 Feb 1998, Ralf Sigmund wrote: > After serveral trys to implement a 4 bit Interface to an HD44780 driven 2 x > 16 LCD display I desperately seek some help. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Ron Kreymborg Computer Systems Manager Monash University CRC for Southern Hemisphere Meteorology Wellington Road Clayton, VIC 3168 Phone : 061-3-9905-9671 Australia Fax : 061-3-9905-9689 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~