Post by thread:[PIC]: Problems using a 1x8 chars LCD

Hi, i've just start programming for the pic and the first real "project" for me was to get a LCD working, after some reading I found that the HD44780 controlled ones was easy to use and common. The code i've made works fine now except for one thing, when printing some text on the LCD i ALWAYS get a weird character(seems to be char code: 10110101) and even when i do a display clear or cursor home i cant get to the first position of the LCD. Is my code wrong or have you experienced this on your own? Heres the put command function(using portb as lcd_data): putcmd_start putcmd movwf lcd_cmd ; the command is in W, just save it bcf LCD_CTRL, LCD_RW ; setup for command recieve bcf LCD_CTRL, LCD_RS bsf LCD_CTRL, LCD_E movf lcd_cmd, 0 movwf LCD_DATA nop ; pulse must be wider than 450ns, is not necessary for fast clocks bcf LCD_CTRL, LCD_E return putcmd_end Thanks! Andreas Eriksson SWEDEN -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

>text on the LCD i ALWAYS get a weird character(seems to be char code: > >10110101) and even when i do a display clear or cursor home i cant get > >to the first position of the LCD. Is my code wrong or have you > >experienced this on your own? Exactly WHERE is this character appearing? In the middle of your display? Before the first desired character is written? At the end of the message? I'll assume it's at the beginning of your message. You have to ensure that the "E" bit is clear before you begin writing. I can't be sure that it is from the code you submitted. If it isn't, then your command line would not be sent until it's toggled again, which would be the next character. This would make your first character/command garbage. Try: bcf LCD_CTRL, LCD_E {Quote hidden}> movwf lcd_cmd ; the command is in W, just save it > bcf LCD_CTRL, LCD_RW ; setup for command recieve > bcf LCD_CTRL, LCD_RS > bsf LCD_CTRL, LCD_E > movf lcd_cmd, 0 > movwf LCD_DATA > nop ; pulse must be wider than 450ns, is not necessary for fast clocks > bcf LCD_CTRL, LCD_E > > return Looks like you're using Peter Ouwehand's routines. Never used them myself, but I assume they'd work. Note that in his routines, he calls LCDBUSY *before* he tries to write to the display. This routine automatically leaves the "E" bit clear. If you still have problems, maybe you could check directly with him about them? --Andrew _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Hi again, and thanks for your rapid reply >>text on the LCD i ALWAYS get a weird character(seems to be char code: >> >10110101) and even when i do a display clear or cursor home i cant get >> >to the first position of the LCD. Is my code wrong or have you >> >experienced this on your own? > >Exactly WHERE is this character appearing? In the middle of your display? >Before the first desired character is written? At the end of the message? >I'll assume it's at the beginning of your message. Sorry, its in the beginning yes... > >You have to ensure that the "E" bit is clear before you begin writing. I >can't be sure that it is from the code you submitted. If it isn't, then >your command line would not be sent until it's toggled again, which would be >the next character. This would make your first character/command garbage. >Try: > I can submit the whole code if thats better? The LCD_E bit isnt set, its cleared from the very beginning of the program {Quote hidden}>bcf LCD_CTRL, LCD_E > >> movwf lcd_cmd ; the command is in W, just save it >> bcf LCD_CTRL, LCD_RW ; setup for command recieve >> bcf LCD_CTRL, LCD_RS >> bsf LCD_CTRL, LCD_E >> movf lcd_cmd, 0 >> movwf LCD_DATA >> nop ; pulse must be wider than 450ns, is not necessary for fast clocks >> bcf LCD_CTRL, LCD_E >> >> return > >Looks like you're using Peter Ouwehand's routines. Never used them myself, >but I assume they'd work. Note that in his routines, he calls LCDBUSY >*before* he tries to write to the display. This routine automatically >leaves the "E" bit clear. > Who is Peter Ouwehand? :-) {Quote hidden}>If you still have problems, maybe you could check directly with him about >them? > >--Andrew > > >_________________________________________________________________ >Get your FREE download of MSN Explorer at http://explorer.msn.com > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body > > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

> > >> movwf lcd_cmd ; the command is in W, just save it > >> bcf LCD_CTRL, LCD_RW ; setup for command recieve > >> bcf LCD_CTRL, LCD_RS > >> bsf LCD_CTRL, LCD_E Dosen't this require NOPs between the instructions, to get around the read-modify-write "feature"? -- Where's dave? http://www.findu.com/cgi-bin/find.cgi?kc6ete-9 -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservspam_OUTTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body