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| Micro Controllers Discuss all aspects of micro controllers - building them, coding them, etc. All controllers are welcome - PIC, BASIC, Z8 Encore!, etc. |
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6th July 2009, 06:59 AM
| #1 |
 lcd using pic18f452
Hi everyone i have started pic hardware two weeks ago , before it i gone through much of it programming in assembly , since three days i m working on interfacing 14 pin lcd with ribbon connection , i m using sipmle program which is downloaded well into ic and progrm is burnt well ,with proper setting of configuration bits , when i interface the lcd it just giving some bullets which shows lcd is fine i m sending u my code and hope 4 ur reply since i m finding no way at there. thanx LIST p=18F452 , F=INHX32, MM=OFF, N=0, ST=OFF , R=HEX #Include P18F452.INC CONFIG OSC=HS , OSCS=OFF CONFIG WDT=OFF CONFIG BORV=45, PWRT=ON, BOR=ON CONFIG DEBUG=OFF, LVP=OFF, STVR=OFF ORG 00h LCD_DATA EQU PORTB LCD_CTRL EQU PORTD R2 EQU 0*2 R3 EQU 0*3 MYREG EQU 0*4 MTREG EQU 0*5 RS EQU RD0 RW EQU RD1 EN EQU RD2 CLRF TRISD CLRF TRISB BCF LCD_CTRL,EN CALL LDELAY MOVLW 0*38 CALL COMNWRT CALL DELAY MOVLW 0*0E CALL COMNWRT CALL DELAY MOVLW 0*01 CALL COMNWRT CALL DELAY MOVLW 0*06 CALL COMNWRT CALL DELAY MOVLW 0*84 CALL COMNWRT CALL DELAY MOVLW A'P' CALL DATAWRT CALL DELAY MOVLW A'A' CALL DATAWRT AGA BTG LCD_CTRL,0 BRA AGA COMNWRT MOVWF LCD_DATA BCF LCD_CTRL,RS BCF LCD_CTRL,RW BCF LCD_CTRL,EN CALL DELAY BCF LCD_CTRL,EN RETURN DATAWRT MOVWF LCD_DATA BSF LCD_CTRL,RS BSF LCD_CTRL,RW BSF LCD_CTRL,EN CALL SDELAY BCF LCD_CTRL,EN RETURN SDELAY MOVLW 0FF MOVWF MYREG ADAIN NOP NOP DECF MYREG,F BNZ ADAIN RETURN LDELAY MOVLW D'200' MOVWF R2 AJAIN MOVLW D'250' MOVWF R3 HERE NOP NOP DECF R3,F BNZ HERE DECF R2,F BNZ AJAIN RETURN DELAY MOVLW D'200' MOVWF MTREG AHAIN NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP NOP DECF MTREG,F BNZ AHAIN RETURN END | |
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6th July 2009, 07:09 AM
| #2 |
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What is your oscillator frequency? An LCD requires a delay of about 5 to 10 ms for every command and a little more for data.What i do is use a longer delay and use one delay loop for all.
__________________ I just cant come up with a good one!  | |
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6th July 2009, 07:14 AM
| #3 |
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You have a couple of errors in your data and command write routines, Code: COMNWRT movwf LCD_DATA bcf LCD_CTRL,RS bcf LCD_CTRL,RW bsf LCD_CTRL,EN ;was bcf call DELAY bcf LCD_CTRL,EN return DATAWRT movwf LCD_DATA bsf LCD_CTRL,RS bcf LCD_CTRL,RW ;was bsf bsf LCD_CTRL,EN call SDELAY bcf LCD_CTRL,EN return | |
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7th July 2009, 03:16 PM
| #4 |
| lcd using pic18f452
thanx pommie I did what u pointed , but still the things are not working at all , interestingly i m also gettting no any display when i m trying to simulate it on proteas , im using 10 Mhz crystal, i have also used it using single delay of 25 msec but it is also not working . i got blank this time , i think i have used correct config setting . Last edited by einton; 7th July 2009 at 03:22 PM. | |
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7th July 2009, 03:28 PM
| #5 |
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You should try and find some working code that you can test your hardware with. If you post a schematic then people may be able to provide working code. Mike. | |
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7th July 2009, 05:08 PM
| #6 |
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It may be the contrast pin is not at the correct voltage, hence the blank screen... As suggested load some working code to test your hardware..
__________________ Eccentric millionaire financed by 'er indoors | |
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7th July 2009, 07:49 PM
| #7 |
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Hi, here is the code, the problem is that the delay is very small due to you using HS mode of the 18F452. Another problem is that you used PORTx for output when you should be using LATx registers.Here is the code and the attached simulation in Proteus. Code: LIST p=18F452;This ones for a 10MHz crystal.When you start ;proteusD.C on the device and change the crystal to 10Mhz. #Include P18F452.INC CONFIG OSC=HS , OSCS=OFF CONFIG WDT=OFF, LVP=OFF ORG 00h MOVLW 07 MOVWF T0CON LCD_DATA EQU LATB LCD_CTRL EQU LATD RS EQU RD0 RW EQU RD1 EN EQU RD2 CLRF TRISD CLRF TRISB BCF LCD_CTRL,EN CALL DELAY MOVLW 0X38 CALL COMNWRT CALL DELAY MOVLW 0X0E CALL COMNWRT CALL DELAY MOVLW 0X01 CALL COMNWRT CALL DELAY MOVLW 0X06 CALL COMNWRT CALL DELAY MOVLW 0X84 CALL COMNWRT CALL DELAY MOVLW A'P' CALL DATAWRT CALL DELAY MOVLW A'A' CALL DATAWRT AGA BTG LCD_CTRL,3 BRA AGA COMNWRT movwf LCD_DATA bcf LCD_CTRL,RS bcf LCD_CTRL,RW bsf LCD_CTRL,EN ;was bcf call DELAY bcf LCD_CTRL,EN return DATAWRT movwf LCD_DATA bsf LCD_CTRL,RS bcf LCD_CTRL,RW ;was bsf bsf LCD_CTRL,EN call DELAY bcf LCD_CTRL,EN return DELAY: MOVLW 4 MOVWF 0X20 AGAIN: MOVLW 0FF MOVWF TMR0H MOVWF TMR0L BCF INTCON,TMR0IF BSF T0CON,TMR0ON DELAY1: BTFSS INTCON,TMR0IF BRA DELAY1 BCF T0CON,TMR0ON DECFSZ 0X20 BRA AGAIN RETURN END
__________________ Syed Last edited by Wond3rboy; 8th July 2009 at 07:36 AM. | |
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| lcd, pic |
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| Display Modes | |
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