Post by thread:[EE] Trouble on 2nd line of LCD

Dear gang, I have this LCD: http://www.futurlec.com/LED/LCD16x2.shtml I can write chars to the LCD and seems to work ok but when I move the cursor to the 2nd line, and write to the LCD, nothing is displayed. To move the cursor the 2nd line, I clear the RS bit, send 0xC0, then pulse the EN bit. The code works as expected on the OSHON PIC IDE/Simulator. Anyone have any ideas on what im doing wrong ? Before writing characters to the LCD, I have this small function to setup the LCD: First I bring the RS bit low and bring the EN bit high movlw 0x38 ; 8bit, 2 line, 5x7 resolution movwf PORTC then I pulse the EN bit movlw 0x0C ; display on, cursor off movwf PORTC pulse the EN bit again movlw 0x01 ; clear LCD display movwf PORTC pulse the EN bit again finally I bring the RS bit high before returning from the routine. Best Regards, Steve Maroney Business Computer Support, LLC Mobile Phone:504-914-4704 Office Phone: 504-904-0266 Fax: 866-871-7797

Are you sure setting up for multiline isn't movlw 0x28 instead of movlw 0x38? I'm just going by some code for another similar display, but it's hard to compare because I've got it in 4 bit mode. I'd say that first you should go back to the datasheet and go over the initialization process with a fine tooth comb - make sure you're also meeting the timing requirements listed, i.e. if it says stay in reset for 25msec, try staying in reset for 100msec, etc.. Tony Steve Maroney wrote: {Quote hidden}> Also, I think I should add that If I turn the contrast all the up, to > where I cant read the chars and see square blocks, I thought I would see > the second row blocks, as I do the first row, but I only see the first > row. > > Hopefully that makes some sense. > > > Best Regards, > Steve Maroney > > Business Computer Support, LLC > Mobile Phone:504-914-4704 > Office Phone: 504-904-0266 > Fax: 866-871-7797 > > > > {Original Message removed}

On Fri, 10 Jul 2009 23:16:18 -0500 "Steve Maroney" <spam_OUTsteveTakeThisOuTbcsupportllc.com> wrote: > Hopefully that makes some sense. If no blocks at all are visible, it is probably because you didn't (correctly) put the LCD in two-line mode at startup. This can only be done once, I believe. The default (even for a two line display) is one line only. Note that those first instructions do not correctly activate the BUSY line - you have to respect the times mentioned in the data sheet, for each of the initialization steps. There is one step that takes even 1.5 ms! If you do not respect those times, the configuration command that selects two-line mode will no be recognized. look for the Hitachi HD44780 datasheet (which is probably the controller chip on the LCD). Quite probably the simulator doesn't respect the timing. John

Check the initialisation... here is an asm snippet that works... ;--------------Lcd handler for pic 16cxx / 5x------------- ;--------------By Steve Smith 1997 onwards---------------- ;--------------RS line reused for other items------------- ;************* LCD FUNCTIONS ****************************** ;LCD_DATA EQU PORTB ; PLACE TO SEND LCD INFO ;#DEFINE LCD_EN PORTA,4 ; LCD ENABLE ;#DEFINE LCD_RS PORTA,3 ; LCD REGISTER SEL ; R/W IS NOT USED (GND) ;------------------MEMORY REQUIREMENTS---------------------------------- STRNUM EQU GP1 +1 ; TEXT STRING NUMBER STORE CHPT EQU STRNUM +1 ; CHAR POINTER LCDCH EQU CHPT +1 ; LCD CHAR TABOFF EQU LCDCH+1 ; TABLE OFFSET ;------------------INCREMEMTS CHARTHER POINTER FOR TEXT STRING---------- POINT MACRO INCF TABOFF,1 MOVFW TABOFF ADDWF PCL,1 ENDM POINT1 MACRO INCF TABOFF,F incf PCLATH,f MOVFW TABOFF ADDWF PCL,F ENDM ;--------------LCD CONTROL FUNCTION EQUATES----------------- LINE1 EQU B'10000000' LINE2 EQU B'11000000' LINE1_8 EQU B'10001000' LINE1_14 EQU B'10001101' LINE2_8 EQU B'11001000' LINE2_6 EQU B'11000101' BLINK EQU B'00001110' NBLINK EQU B'00001100' S_P EQU 020h LCD_INIT MACRO ;--------------LCD INITALISATION CODE----------------------- MOVLW 38h ; LCD RESET CALL LCD_CMD ; DO INSTRUCTION MOVLW 06h ; DISPLAY DIR RIGHT CALL LCD_CMD ; DO INSTRUCTION MOVLW 0Ch ; DISPLAY ON AND CURSER SET CALL LCD_CMD ; DO INSTRUCTION ENDM ;--------------------------------LCD TEXT STRING HANDLER--------------------- STRING IF DEBUG == 1 ; REMOVE COMMENT DURING DEBUG RETLW 0 ELSE MOVWF STRNUM ; SAVE STRING NUMBER MOVLW 0FFH ; POINTER TO BEGINING OF STRING MOVWF TABOFF ; WELL IT IS NOW DOSTR PAGE1 ; SET PAGE MARKER CALL CALLSTR ; GET STRING CHAR POINTED TO IN TABOFF PAGE0 ; RESET PAGE MARKER MOVWF LCDCH ; SAVE CHAR ANDLW B'01111111' ; MASK END BIT (END OF STRING MARKER) CALL LCD_OUT ; SEND CHAR BTFSS LCDCH,7 ; CHECK LAST GOTO DOSTR ; NOT FINISHED DO SOME MORE RETLW 0 ; EXIT ENDIF LCD_CMD BCF LCD_RS ; CONTROL MODE goto LCD_OUT_1 LCD_OUT BSF LCD_RS ; data mode LCD_OUT_1 MOVWF LCD_DATA ; PUT LCD CONTROL DATA ON BUS ; 1us port settle time NOP BSF LCD_EN ; Lcd enable High SEND IT NOP ; 1us port settle time BCF LCD_EN ; Lcd enable low BSF LCD_RS ; RESET RS LINE ; btfss COM_F ; flag for line ; BCF LCD_RS MOVLW .20 ; short delay period GOTO SHORT ; short delay ;--------------LCD CLEAR DISPLAY----------------------------------- LCDCLR MOVLW 01h ; CLEAR DISPLAY CALL LCD_CMD ; SHORT TIME DELAY MOVLW .3 ; LONG DELAY PERIOD GOTO LONG ; DO TIME ;************* END LCD FUNCTIONS ************************ ;--------------TEXT STRINGS------------------------------ ; ORG 200 ;LAST EQU b'10000000' ;CALLSTR ; MOVFW STRNUM ; GET STRING ; ADDWF PCL,1 ; WHICH STRING ; RETLW '0'+LAST ; GOTO MSG7 ; ON ; GOTO MSG8 ; OFF ; GOTO MSG9 ; FAULT ;MSG7 POINT ; RETLW 'O' ; RETLW 'N' ; RETLW ' '+LAST ;MSG8 POINT ; RETLW 'O' ; RETLW 'F' ; RETLW 'F'+LAST ;MSG9 POINT ; RETLW 'F' ; RETLW 'A' ; RETLW 'U' ; RETLW 'L' ; RETLW 'T' ; RETLW ' '+LAST {Original Message removed}

At 09:31 PM 7/10/2009, Steve Maroney wrote: >Dear gang, > >I have this LCD: http://www.futurlec.com/LED/LCD16x2.shtml > >I can write chars to the LCD and seems to work ok but when I move the >cursor to the 2nd line, and write to the LCD, nothing is displayed. There are two different styles of 2-line LCD display - those whose 2nd line start address begins right after the 1st line finishes and a similar-looking display whose 2nd line start address begins at (I think) either decimal 40 or decimal 80. I suspect that you are running into that problem. Sorry that I can't remember the specific details right now but it might prompt someone else to chime in with the start address of the 2nd line. If not, I'll look it up and post another message later today. Hope this helps! dwayne -- Dwayne Reid <.....dwaynerKILLspam@spam@planet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax http://www.trinity-electronics.com Custom Electronics Design and Manufacturing

>> I have this LCD: http://www.futurlec.com/LED/LCD16x2.shtml > > There are two different styles of 2-line LCD display - those whose > 2nd line start address begins right after the 1st line finishes and a > similar-looking display whose 2nd line start address begins at (I > think) either decimal 40 or decimal 80. I suspect that you are > running into that problem. > > Sorry that I can't remember the specific details right now but it > might prompt someone else to chime in with the start address of the > 2nd line. When all magic and guesswork fails, where do you go for help? Hint: follow the URL.. No, not the ones in my sig. -- Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

position index for second line is starts at 40. actual move value is 68 something. try it, you will find correct index value. ----- Original Message ----- From: "Steve Maroney" <steveKILLspambcsupportllc.com> To: "Microcontroller discussion list - Public." <.....piclistKILLspam.....mit.edu> Sent: Sunday, July 12, 2009 12:46 AM Subject: RE: [EE] Trouble on 2nd line of LCD {Quote hidden}> In order to contribute to this list, I've wanted to let you guys know > that I found my problem. > > In my lcd_init routinue, I was sending the function set instructions (2 > lines, 8bit, resolutions, etc) BEFORE my next command, which was turning > on the LCD and homing the cursor. > > The solution was to first turn on the LCD, then to send the setup > instructions, then clear the LCD just in case there is chars on the > display. > > Thanks for the help. > > > Best Regards, > Steve Maroney > > Business Computer Support, LLC > Mobile Phone:504-914-4704 > Office Phone: 504-904-0266 > Fax: 866-871-7797 > > > > {Original Message removed}