Post by thread:[PIC]:PCLATH still not working..code review?

ok...i removed everything from the code except the necessary pieces to just sent the word "test" to the LCD. First I kept the code in the same page and it works fine...then changed to call from the second page, and it fails to display. ------------------------------------------------------------------------- list p=16F874 ; list directive to define processor #include <p16F874.inc> ; processor specific variable definitions __CONFIG _HS_OSC & _WDT_OFF & _CP_OFF & _CPD_OFF & _BODEN_OFF & _LVP_OFF & _WRT_ENABLE_ON & _PWRTE_ON & _DEBUG_OFF ERRORLEVEL -302 ;Supress incorrect bank selection message ERRORLEVEL -306 ;Supress Crossing page boundary message ERRORLEVEL +312 ;Page or Bank selection not needed for this device. No code generated. ERRORLEVEL +307 ;Setting page bits. #include stc2.equ org 0x000 ; The main line code starts here main: goto init org 0x004 ; interupt vector retfie ;return from interrupt init: movlw 0xFF ; set for input movwf TRISB ; TRISB direction register movlw 0x3F ; 0011 1111 upper two bits are outputs to LCD tris PORTC ; TRISC direction register ; initilize port A, since it can be both an analog or digital port bcf STATUS, RP0 BCF STATUS, RP1 clrf PORTA bsf STATUS, RP0 movlw 0x00 tris PORTA movlw 0x00 ; clear the register movwf PORTA ; and be sure all the relays are turned off movlw 0x00 ; set for output movwf 0x89 ; Port E TRISE direction register movlw 0x00 ; set for output movwf 0x88 ; Port D TRISD direction register BCF STATUS, RP1 BCF STATUS, RP0 clrf PORTD clrf PORTE call InitLCD am: bsf PCLATH,3 call SPLASH bcf PCLATH,3 goto am Send_LCD_Data ; SENDLCDDATA Sends a byte as a data to the LCD. bsf PORTC,6 ; LCD_RS_BIT movwf PORTD ; OK. Data is on the LCD data pins bsf PORTC,7 ;LCD_E_BIT bcf PORTC,7 ;LCD_E_BIT movlw DELAY_50MS_HI movwf DELAYHI movlw DELAY_50MS_LO movwf DELAYLO call Delay return InitLCD call Delay movlw 0x38 ; TWO Lines option movwf ARG1 call SendLCDCommand call Delay ; Send 0x0C (or 0x0F) movlw 0x0C movwf ARG1 call SendLCDCommand call Delay ; Send 0x03 movlw 0x03 movwf ARG1 call SendLCDCommand call Delay call Delay call Delay ; Send 0x06 ** Set AUTOINC, and NO Shifting movlw 0x06 movwf ARG1 call SendLCDCommand call Delay ; Send 0x02 ** (HOME) movlw 0x02 movwf ARG1 call SendLCDCommand call Delay retlw 0 ; General DELAY routine ; Inputs: ; DELAYHI - Initial Countdown value MSB ; DELAYLO - Initial Countdown value LSB ; Uses: ; COUNTHI - Counter value MSB ; COUNTLO - Counter value LSB Delay movlw DELAY_50MS_HI movwf DELAYHI movlw DELAY_50MS_LO movwf DELAYLO movf DELAYHI, W movwf COUNTHI movf DELAYLO, W movwf COUNTLO DelayLoop decfsz COUNTLO,1 goto DelayLoop decfsz COUNTHI,1 goto DelaySetup goto DelayDone DelaySetup movf DELAYLO, W movwf COUNTLO goto DelayLoop DelayDone retlw 0 SendLCDCommand ; SENDLCDCOMMAND Sends a byte as a command to the LCD. bcf PORTC,6 ; LCD_RS_BIT movf ARG1, W movwf PORTD ; OK. Data is on the LCD data pins bsf PORTC,7 ;LCD_E_BIT bcf PORTC,7 ;LCD_E_BIT retlw 0 SendLCDData ; SENDLCDDATA Sends a byte as a data to the LCD. bsf PORTC,6 ; LCD_RS_BIT movwf PORTD ; OK. Data is on the LCD data pins bsf PORTC,7 ;LCD_E_BIT bcf PORTC,7 ;LCD_E_BIT call Delay retlw 0 CLEAR_LCD ; Send 0x01 ** Clear movlw 0x01 movwf ARG1 call SendLCDCommand call Delay call Delay return LDC ; long delay loop movlw d'40' movwf TEMP LDCLOOP: call Delay decfsz TEMP,1 goto LDCLOOP return org 0x800 SPLASH: movlw 0x80 movwf ARG1 call SendLCDCommand call Delay movlw _T call Send_LCD_Data movlw _e call Send_LCD_Data movlw _s call Send_LCD_Data movlw _t call Send_LCD_Data return end ____________________________________________________________________ Get free email and a permanent address at http://www.netaddress.com/?N=1 -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

{Quote hidden}> am: > bsf PCLATH,3 > call SPLASH > bcf PCLATH,3 > goto am > > org 0x800 > > SPLASH: > movlw 0x80 = > > movwf ARG1 > call SendLCDCommand > call Delay > movlw _T > call Send_LCD_Data > movlw _e > call Send_LCD_Data > movlw _s > call Send_LCD_Data > movlw _t > call Send_LCD_Data > return > > end You set PCLATH correctly before calling SPLASH and restore it afterwords, but you forgot to do this inside SPLASH when calling SENDLCDCOMMAND, DELAY, etc. You should check out my GCALL and related macros in STD.INS.ASPIC at http://www.embedinc.com/pic. GCALL (Global CALL) automatically does the PCLATH diddling before and after calling a subroutine. MCALL (Module CALL) is for calling a subroutine withing a module, which is assumed to be all within one page. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, spam_OUTolinTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.