; GPR's (General Purpose Registers) are used for the following:
    ;H070 and H071: counters for short delay and utility delay
    ;H072 used to temporarily store characters
    ;H075 used as offset counter in our tables.
    
    list      p=16F1455        ; list directive to define processor
    #include "p16F1455.inc"        ; processor specific variable definitions
 __CONFIG _CONFIG1, _FOSC_INTOSC & _WDTE_OFF & _PWRTE_OFF & _MCLRE_ON & _CP_OFF & _BOREN_ON & _CLKOUTEN_OFF & _IESO_ON & _FCMEN_ON
 __CONFIG _CONFIG2, _WRT_OFF & _CPUDIV_NOCLKDIV & _USBLSCLK_48MHz & _PLLMULT_3x & _PLLEN_DISABLED & _STVREN_ON & _BORV_LO & _LPBOR_OFF & _LVP_ON

    errorlevel  -302 , -207             ; suppress message 302 from list file
  banksel OSCCON
  movlw B'00101110' ; we need to slow down the processor for the LCD display driver. Max 2 Mhz. We'll run at 1 Mhz
  movwf OSCCON
  
  ; everything above this line is simply setting up the processor at 1 MHz.
  
    banksel TRISA  ; set up PORTA for outputs
    clrf TRISA 
    banksel LATA  ; Don't forget this! LATA and TRISA are NOT in the same bank, though they are both for the same register!
    clrf LATA  ;this sends out RS=0 and E=0 from PORTA to the control lines on the LCD display
    call utility_delay ; waits about 0.8 seconds for display to initialize
    banksel TRISC
    clrf TRISC ; we can now set PORTC to all outputs
    ; we'll now set the display to 4 bit mode
    ;NOTE: all binary numbers must include all 8 bits. However, only the lower 4 bits are actually connected and therefore, used
    banksel LATC
    movlw B'00000010' ;send first command for 4 bit mode.  The lower nibble is actually 0000, but not connected. This is the upper nibble
    movwf LATC
    call pulse_e
    banksel LATC
    movlw B'00000010' ;send upper nibble command to 4 bit mode.
    movwf LATC
    call pulse_e  
    ; We are now in 4 bit mode.
    banksel LATC
    movlw B'00001100' ;send lower nibble command to 4 bit mode and two line mode.
    movwf LATC
    call pulse_e
    ; we are now in 4 bit, 2 line mode.
    banksel LATC
    movlw B'00000000' ;send upper nibble to turn on display, set cursor.
    movwf LATC
    call pulse_e
    banksel LATC
    movlw B'00001111' ;send lower nibble to turn on display, set cursor.
    movwf LATC
    call pulse_e
    ; The display is now turned on, with a flashing underline cursor at the current character location
    banksel LATA
    bsf LATA,4 ; sets RS to 1, putting it into CHARACTER mode
    banksel LATC
    
    
        
    ;##############manually add a capital A#################
    ;This section manually adds a capital A to the display at the current cursor location.
    ;Simply copy and paste this section for every letter you wish to add.
    movlw B'00000100' ;first nibble of first character, a capital A
    movwf LATC
    call pulse_e
    banksel LATC
    movlw B'00000001' ; the second nibble of capital A is loaded onto LATC
    movwf LATC
    call pulse_e
    ;##############end of manually add a capital A#################

    ;##############manually add another letter#################
    ;As you can see, I've simply copied and pasted the code to add a second letter.
    ;Simply copy and paste e code section for every letter you wish to add, leave out the comments if you want.
    movlw B'00000100' ;first nibble of first character, a capital C - just look at yer fancy high-tech ASCII chart to figure out your nibbles
    movwf LATC
    call pulse_e
    banksel LATC
    movlw B'00000011' ; the second nibble of capital C is loaded onto LATC
    movwf LATC
    call pulse_e
    ;##############end of manually add a capital A#################


 
endless_loop
    goto endless_loop

    
utility_delay:  ; this subroutine is a utility delay that counts down from 255 255 times. That's a total count of 65025. It takes approximately 0.8 seconds at 1 MHz
  movlw D'255'
  movwf H'070'  ; load 255 into first register
  movlw D'255'
  movwf H'071'  ; load 255 into second register
subloop:
  decfsz H'070', 1 ; count down in first register till we hit 0
  goto subloop
  movlw D'255'
  movwf H'070'  ; load 255 into first register again
  decfsz H'071', 1 ; count down 1 on second register. If we're at 0, we've now gone through 255 loops of 255. Return back to the main program.
  goto subloop
  return
  

  
pulse_e:
    banksel LATA
    bsf LATA,5  ;sends one pulse on the E line
    nop ; waitaminit
    nop ; waitaminit
    bcf LATA,5  ;sets E line to low
    nop ; waitaminit
    nop ; waitaminit
    return
 

     end