include "lcd.inc" ;LcdInicializa ; Right now, the display could be either in 8-bit mode if we ; just powered up, or it could be in 4-bit mode if we just ; experienced a reset. So to begin, we have to initialize the ; display to a known state: the 8-bit mode. This is done by ; sending the LCD command "Function Set" with the 8-bit mode ; bit set. We need to do this 3 times! ; LcdInicializa ;Initialize the LCD_PORT control and data lines to outputs bsf STATUS, RP0 ; Banco 0 bcf LCD_E_PORT, LCD_E bcf LCD_RS_PORT, LCD_RS bcf LCD_RW_PORT, LCD_RW bcf STATUS, RP0 ; Banco 1 movlw ~LCD_DATA_MASK andwf LCD_DATA_PORT,F ;Clear the control lines bsf STATUS, RP0 ;Select Register page 1 andwf LCD_DATA_TRIS,F ;Make LCD_PORT IO lines outputs bcf STATUS, RP0 ;Select Register page 0 movlw 3 movwf TMP1 ;Use TMP1 as a loop counter bcf LCD_E_PORT, LCD_E bcf LCD_RS_PORT, LCD_RS bcf LCD_RW_PORT, LCD_RW init_8bit: call LcdDelay movf LCD_DATA_PORT,W andlw ~LCD_DATA_MASK iorlw (LCD_FUNCTION_SET | LCD_8BIT_INTERFACE) >> LCD_DATA_SHIFT movwf LCD_DATA_PORT ;Put command on the bus ;goto $+1 bsf LCD_E_PORT, LCD_E ;Enable the LCD, i.e. write the command. ;goto $+1 ;NOP's are only needed for 20Mhz crystal ;goto $+1 bcf LCD_E_PORT, LCD_E ;Disable the LCD decfsz TMP1, F goto init_8bit ;We should now have the LCD module in 8-bit mode. Now let's put it in 4-bit mode call LcdDelay movf LCD_DATA_PORT,W andlw ~LCD_DATA_MASK iorlw (LCD_FUNCTION_SET | LCD_4BIT_INTERFACE) >> LCD_DATA_SHIFT movwf LCD_DATA_PORT ;Put command on the bus ;goto $+1 bsf LCD_E_PORT, LCD_E ;Enable the LCD, i.e. write the command. ;goto $+1 ;NOP's are only needed for 20Mhz crystal ;goto $+1 bcf LCD_E_PORT, LCD_E ;Disable the LCD call LcdDelay ;Now we are in 4-bit mode. This means that all reads and writes of bytes have to be done ;a nibble at a time. But that's all taken care of by the read/write functions. ;Set up the display to have 2 lines and the small (5x7 dot) font. movlw LCD_FUNCTION_SET | LCD_4BIT_INTERFACE | LCD_2_LINES | LCD_SMALL_FONT call LcdWriteCommand ;Turn on the display and turn off the cursor. Set the cursor to the non-blink mode movlw LCD_DISPLAY_CONTROL | LCD_DISPLAY_ON | LCD_CURSOR_OFF | LCD_BLINKING_OFF call LcdWriteCommand ;Clear the display memory. This command also moves the cursor to the home position. movlw LCD_CLEAR_DISPLAY call LcdWriteCommand ;Set up the cursor mode. movlw LCD_ENTRY_MODE_SET | LCD_INC_CURSOR_POS | LCD_NO_SCROLL call LcdWriteCommand ;Set the Display Data RAM address to 0 movlw LCD_SET_DDRAM call LcdWriteCommand call LcdClearScreen return ;******************************************************************* ;LcdDelay ; This routine takes the calculated times that the delay loop needs to ;be executed, based on the LCD_INIT_DELAY EQUate that includes the ;frequency of operation. ; LcdDelay movlw LCD_INIT_DELAY ; A_DELAY movwf TMP1 ; Use TMP1 and TMP2 clrf TMP2 ; LOOP2 decfsz TMP2, F ; Delay time = TMP1 * ((3 * 256) + 3) * Tcy goto LOOP2 ; = TMP1 * 154.2 (20Mhz clock) decfsz TMP1, F ; goto LOOP2 ; return ;******************************************************************* ;LcdToggleE ; This routine toggles the "E" bit (enable) on the LCD module. The contents ;of W contain the state of the R/W and RS bits along with the data that's ;to be written (that is if data is to be written). The contents of the LCD port ;while E is active are returned in W. ; LcdToggleE bcf LCD_E_PORT,LCD_E ;Make sure E is low movlw 0 LTE1: ;goto $+1 ;Delays needed primarily for 10Mhz and faster clocks ;goto $+1 ;goto $+1 btfsc LCD_E_PORT, LCD_E ;E is low the first time through the loop goto LTE2 bsf LCD_E_PORT, LCD_E ;Make E high and go through the loop again goto LTE1 LTE2: addlw 1 skpz goto LTE2 movf LCD_DATA_PORT, W ;Read the LCD Data bus andlw LCD_DATA_MASK ;We're only interested in the data lines bcf LCD_E_PORT, LCD_E ;Turn off E return ;******************************************************************* ;LcdWriteData - Sends a character to LCD ; This routine splits the character into the upper and lower ;nibbles and sends them to the LCD, upper nibble first. ; ; Memory used: ; LCD_CHAR, ; Calls ; LcdToggleE ; LcdWriteData movwf LCD_CHAR ;Character to be sent is in W call LcdBusyCheck ;Wait for LCD to be ready bsf LCD_RS_PORT,LCD_RS bcf LCD_RW_PORT,LCD_RW LCD_WRITE if LCD_DATA_MASK == 0x0f swapf LCD_CHAR,F endif ;First, write the upper nibble movf LCD_CHAR, w andlw LCD_DATA_MASK movwf TMP1 movf LCD_DATA_PORT,W andlw ~LCD_DATA_MASK iorwf TMP1,W movwf LCD_DATA_PORT call LcdToggleE ;Next, write the lower nibble swapf LCD_CHAR, w andlw LCD_DATA_MASK movwf TMP1 movf LCD_DATA_PORT,W andlw ~LCD_DATA_MASK iorwf TMP1,W movwf LCD_DATA_PORT goto LcdToggleE ;******************************************************************* ;LcdWriteCommand ; ; This routine splits the command into the upper and lower ;nibbles and sends them to the LCD, upper nibble first. ; LcdWriteCommand movwf LCD_CHAR ;Character to be sent is in W call LcdBusyCheck ;Wait for LCD to be ready ;Both R_W and RS should be low bcf LCD_RS_PORT,LCD_RS bcf LCD_RW_PORT,LCD_RW goto LCD_WRITE ;******************************************************************* ;LcdReadData ;This routine will read 8 bits of data from the LCD. Since we're using ;4-bit mode, two passes have to be made. On the first pass we read the ;upper nibble, and on the second the lower. ; LcdReadData call LcdBusyCheck ;For a data read, RS and R/W should be high bsf LCD_RS_PORT,LCD_RS bsf LCD_RW_PORT,LCD_RW LcdRead bsf STATUS, RP0 ;Select Register page 1 movf LCD_DATA_TRIS,W ;Get the current setting for the whole register iorlw LCD_DATA_MASK ;Set the TRIS bits- make all of the data movwf LCD_DATA_TRIS ; lines inputs. bcf STATUS, RP0 ;Select Register page 0 call LcdToggleE ;Toggle E and read upper nibble movwf TMP2 ;Save the upper nibble call LcdToggleE ;Toggle E and read lower nibble movwf TMP1 ;Save the lower nibble swapf TMP1, W ;Put the lower nibble of data in lower half of W iorwf TMP2, F ;Combine nibbles bsf STATUS, RP0 ;Select Register page 1 movlw ~LCD_DATA_MASK ;Clear the TRIS bits- make all of the data andwf LCD_DATA_TRIS,F ; lines outputs. bcf STATUS, RP0 ;Select Register page 0 movf TMP2,W if LCD_DATA_MASK == 0x0f swapf TMP2,W endif return ;******************************************************************* ;LcdBusyCheck ;This routine checks the busy flag, returns when not busy ; LcdBusyCheck ;For a busy check, RS is low and R/W is high bcf LCD_RS_PORT,LCD_RS bsf LCD_RW_PORT,LCD_RW call LcdRead andlw 0x80 ;Check busy flag, high = busy skpnz return movlw 5 call A_DELAY goto LcdBusyCheck ;If busy, check again ;******************************************************************* ;LcdClearScreen ; LcdClearScreen movlw 20-1 movwf LCD_BUFFER0 movlw LCD_SET_DDRAM | LCD_ROW_0 | LCD_COL_0 lcs1: call LcdWriteCommand lcs2: movlw 0x20 ;ASCII space call LcdWriteData decf LCD_BUFFER0,W movwf LCD_BUFFER0 btfss LCD_BUFFER0,6 ;See if we generated a borrow goto lcs2 btfss LCD_BUFFER0,7 ;First time through, borrow should be in 7 too return movlw 20-1 + 0x80 ;Reload count and set bit 7 (borrow will clear it) movwf LCD_BUFFER0 movlw LCD_SET_DDRAM | LCD_ROW_1 | LCD_COL_0 goto lcs1