lcd interfacing
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From: abhay on 4 Aug 2006 13:30 hi .i m interfacing 16x2 lcd to my P89LPC935 but i m unable to get the desired output.i hav tested many times and also the program is correct as i m able to debug it & observe the output correctly.i hav also replaced my lcd one time. i m using HY-1602F6 lcd module.i hav checked my pin configurations again & again but the lcd is just flashing with backlight voltage input pins. i m getting only blocks of one row display with no character when i change the contrast. Could anyone helpme out in this as i hav to complete my project with this lcd module soon .also i would be thankful if anyone could suggest anyother lcd module for reliable & low cost operation.
From: martin griffith on 4 Aug 2006 14:20 On 4 Aug 2006 10:30:17 -0700, in comp.arch.embedded "abhay" <abhaym244(a)gmail.com> wrote: >hi .i m interfacing 16x2 lcd to my P89LPC935 but i m unable to get >the desired output.i hav tested many times and also the program is >correct as i m able to debug it & observe the output correctly.i hav >also replaced my lcd one time. i m using HY-1602F6 lcd module.i hav >checked my pin configurations again & again but the lcd is just >flashing with backlight voltage input pins. >i m getting only blocks of one row display with no character when i >change the contrast. > >Could anyone helpme out in this as i hav to complete my project with >this lcd module soon .also i would be thankful if anyone could suggest >anyother lcd module for reliable & low cost operation. The first answer to this problem is: Power On Reset you have to have a significant delay, Many milliseconds, before attempting to intitialise an LCD. See your data sheet martin
From: Paul Carpenter on 4 Aug 2006 14:43 On 4 Aug, in article <1154712617.632509.193850(a)m79g2000cwm.googlegroups.com> abhaym244(a)gmail.com "abhay" wrote: >hi .i m interfacing 16x2 lcd to my P89LPC935 but i m unable to get >the desired output.i hav tested many times and also the program is >correct as i m able to debug it & observe the output correctly.i hav How have you determined the timing and delays of your program? >also replaced my lcd one time. i m using HY-1602F6 lcd module.i hav No doubt using a HD44870 or clone controller chip. >checked my pin configurations again & again but the lcd is just >flashing with backlight voltage input pins. What do you mean by 'flashing'. >i m getting only blocks of one row display with no character when i >change the contrast. > >Could anyone helpme out in this as i hav to complete my project with >this lcd module soon .also i would be thankful if anyone could suggest >anyother lcd module for reliable & low cost operation. What delays do you have between writes to the display? What are your initialisation delays? Are you sure you are configuring 4 and 8 bit transfer correctly. How are you determining that your end is right? -- Paul Carpenter | paul(a)pcserviceselectronics.co.uk <http://www.pcserviceselectronics.co.uk/> PC Services <http://www.gnuh8.org.uk/> GNU H8 & mailing list info <http://www.badweb.org.uk/> For those web sites you hate
From: abhay on 5 Aug 2006 01:09 i hav done my lcd interfacing through delay function & through polling of busy flag. in delay program i gave a delay of 250ms. by flashing i mean to say that the lcd is lit when i switch on the power but it displays only one line (the bricks in one line)& i hav correctly checked my configuring for 8 byte data transfer. my initialisation instructions are 0x38h,0x80h,0x06h,0x0Eh,0x01h. i hav read the datasheet & recommended delay was of 1.64ms & 40usec for some instructions So tomake program simpler i tried with 3ms delay for each instruction. i m having a doubt in initialising commands.do i need to initialise something else? also is there something that i could do with my lcd module itself(like any jumper setting) although i hav tried with that also but of no use
From: Aly on 5 Aug 2006 05:32
"abhay" <abhaym244(a)gmail.com> wrote in message news:1154754568.051505.95120(a)i42g2000cwa.googlegroups.com... > > i hav done my lcd interfacing through delay function & through polling > of busy flag. > in delay program i gave a delay of 250ms. > by flashing i mean to say that the lcd is lit when i switch on the > power but it displays only one line (the bricks in one line)& i hav > correctly checked my configuring for 8 byte data transfer. > my initialisation instructions are 0x38h,0x80h,0x06h,0x0Eh,0x01h. i hav > read the datasheet & recommended delay was of 1.64ms & 40usec for some > instructions So tomake program simpler i tried with 3ms delay for each > instruction. > i m having a doubt in initialising commands.do i need to initialise > something else? > also is there something that i could do with my lcd module itself(like > any jumper setting) although i hav tried with that also but of no use > Is the LCD drive voltage right? Some of these LCDs need a negative voltage on the drive, say generated by a 7660 inverter. Other LCDs need Vo sitting on a potentiometer between Vss and Vdd. Would this information help some :) http://www.piclist.com/techref/lcds.htm The approach I've used in the past is to literally bit bang the port with quite messy code, and then once the timings and LCD works, I then manage the output via a timer so that everything is precise. Each manufacturer's LCD is just slightly different in how it does things. Are you reading the busy flag? This may be another approach. Can you enable RS232 on your microcontroller so you can see what's going on? You will get there, it'll eventually work :-) |