PIC Tutorial Three - LCD Modules
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Tutorial 3.1 - requires Main Board and LCD Board.
;LCD text demo - 4 bit mode ;Nigel Goodwin 2002 LIST p=16F628 ;tell assembler what chip we are using include "P16F628.inc" ;include the defaults for the chip ERRORLEVEL 0, -302 ;suppress bank selection messages __config 0x3D18 ;sets the configuration settings (oscillator type etc.) cblock 0x20 ;start of general purpose registers count ;used in looping routines count1 ;used in delay routine counta ;used in delay routine countb ;used in delay routine tmp1 ;temporary storage tmp2 templcd ;temp store for 4 bit mode templcd2 endc LCD_PORT Equ PORTA LCD_TRIS Equ TRISA LCD_RS Equ 0x04 ;LCD handshake lines LCD_RW Equ 0x06 LCD_E Equ 0x07 org 0x0000 movlw 0x07 movwf CMCON ;turn comparators off (make it like a 16F84) Initialise clrf count clrf PORTA clrf PORTB SetPorts bsf STATUS, RP0 ;select bank 1 movlw 0x00 ;make all pins outputs movwf LCD_TRIS bcf STATUS, RP0 ;select bank 0 call Delay100 ;wait for LCD to settle call LCD_Init ;setup LCD clrf count ;set counter register to zero Message movf count, w ;put counter value in W call Text ;get a character from the text table xorlw 0x00 ;is it a zero? btfsc STATUS, Z goto NextMessage call LCD_Char call Delay255 incf count, f goto Message NextMessage call LCD_Line2 ;move to 2nd row, first column clrf count ;set counter register to zero Message2 movf count, w ;put counter value in W call Text2 ;get a character from the text table xorlw 0x00 ;is it a zero? btfsc STATUS, Z goto EndMessage call LCD_Char incf count, f goto Message2 EndMessage Stop goto Stop ;endless loop ;Subroutines and text tables ;LCD routines ;Initialise LCD LCD_Init movlw 0x20 ;Set 4 bit mode call LCD_Cmd movlw 0x28 ;Set display shift call LCD_Cmd movlw 0x06 ;Set display character mode call LCD_Cmd movlw 0x0d ;Set display on/off and cursor command call LCD_Cmd call LCD_Clr ;clear display retlw 0x00 ; command set routine LCD_Cmd movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 0 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 0 call Pulse_e ;Pulse the E line high call Delay5 retlw 0x00 LCD_CharD addlw 0x30 LCD_Char movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high call Delay5 retlw 0x00 LCD_Line1 movlw 0x80 ;move to 1st row, first column call LCD_Cmd retlw 0x00 LCD_Line2 movlw 0xc0 ;move to 2nd row, first column call LCD_Cmd retlw 0x00 LCD_Line1W addlw 0x80 ;move to 1st row, column W call LCD_Cmd retlw 0x00 LCD_Line2W addlw 0xc0 ;move to 2nd row, column W call LCD_Cmd retlw 0x00 LCD_CurOn movlw 0x0d ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_CurOff movlw 0x0c ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_Clr movlw 0x01 ;Clear display call LCD_Cmd retlw 0x00 LCD_HEX movwf tmp1 swapf tmp1, w andlw 0x0f call HEX_Table call LCD_Char movf tmp1, w andlw 0x0f call HEX_Table call LCD_Char retlw 0x00 Delay255 movlw 0xff ;delay 255 mS goto d0 Delay100 movlw d'100' ;delay 100mS goto d0 Delay50 movlw d'50' ;delay 50mS goto d0 Delay20 movlw d'20' ;delay 20mS goto d0 Delay5 movlw 0x05 ;delay 5.000 ms (4 MHz clock) d0 movwf count1 d1 movlw 0xC7 ;delay 1mS movwf counta movlw 0x01 movwf countb Delay_0 decfsz counta, f goto $+2 decfsz countb, f goto Delay_0 decfsz count1 ,f goto d1 retlw 0x00 Pulse_e bsf LCD_PORT, LCD_E nop bcf LCD_PORT, LCD_E retlw 0x00 ;end of LCD routines HEX_Table ADDWF PCL , f RETLW 0x30 RETLW 0x31 RETLW 0x32 RETLW 0x33 RETLW 0x34 RETLW 0x35 RETLW 0x36 RETLW 0x37 RETLW 0x38 RETLW 0x39 RETLW 0x41 RETLW 0x42 RETLW 0x43 RETLW 0x44 RETLW 0x45 RETLW 0x46 Text addwf PCL, f retlw 'H' retlw 'e' retlw 'l' retlw 'l' retlw 'o' retlw 0x00 Text2 ADDWF PCL, f RETLW 'R' RETLW 'e' RETLW 'a' RETLW 'd' RETLW 'y' RETLW '.' RETLW '.' RETLW '.' RETLW 0x00 end
Tutorial 3.2 - requires Main Board and LCD Board.
;LCD 16 bit counter ;Nigel Goodwin 2002 LIST p=16F628 ;tell assembler what chip we are using include "P16F628.inc" ;include the defaults for the chip ERRORLEVEL 0, -302 ;suppress bank selection messages __config 0x3D18 ;sets the configuration settings (oscillator type etc.) cblock 0x20 ;start of general purpose registers count ;used in looping routines count1 ;used in delay routine counta ;used in delay routine countb ;used in delay routine tmp1 ;temporary storage tmp2 templcd ;temp store for 4 bit mode templcd2 NumL ;Binary inputs for decimal convert routine NumH TenK ;Decimal outputs from convert routine Thou Hund Tens Ones endc LCD_PORT Equ PORTA LCD_TRIS Equ TRISA LCD_RS Equ 0x04 ;LCD handshake lines LCD_RW Equ 0x06 LCD_E Equ 0x07 org 0x0000 movlw 0x07 movwf CMCON ;turn comparators off (make it like a 16F84) Initialise clrf count clrf PORTA clrf PORTB clrf NumL clrf NumH SetPorts bsf STATUS, RP0 ;select bank 1 movlw 0x00 ;make all pins outputs movwf LCD_TRIS bcf STATUS, RP0 ;select bank 0 call LCD_Init ;setup LCD clrf count ;set counter register to zero Message movf count, w ;put counter value in W call Text ;get a character from the text table xorlw 0x00 ;is it a zero? btfsc STATUS, Z goto NextMessage call LCD_Char incf count, f goto Message NextMessage call LCD_Line2 ;move to 2nd row, first column call Convert ;convert to decimal movf TenK, w ;display decimal characters call LCD_CharD ;using LCD_CharD to convert to ASCII movf Thou, w call LCD_CharD movf Hund, w call LCD_CharD movf Tens, w call LCD_CharD movf Ones, w call LCD_CharD movlw ' ' ;display a 'space' call LCD_Char movf NumH, w ;and counter in hexadecimal call LCD_HEX movf NumL, w call LCD_HEX incfsz NumL, f goto Next incf NumH, f Next call Delay255 ;wait so you can see the digits change goto NextMessage ;Subroutines and text tables ;LCD routines ;Initialise LCD LCD_Init call Delay100 ;wait for LCD to settle movlw 0x20 ;Set 4 bit mode call LCD_Cmd movlw 0x28 ;Set display shift call LCD_Cmd movlw 0x06 ;Set display character mode call LCD_Cmd movlw 0x0c ;Set display on/off and cursor command call LCD_Cmd ;Set cursor off call LCD_Clr ;clear display retlw 0x00 ; command set routine LCD_Cmd movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high call Delay5 retlw 0x00 LCD_CharD addlw 0x30 ;add 0x30 to convert to ASCII LCD_Char movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high call Delay5 retlw 0x00 LCD_Line1 movlw 0x80 ;move to 1st row, first column call LCD_Cmd retlw 0x00 LCD_Line2 movlw 0xc0 ;move to 2nd row, first column call LCD_Cmd retlw 0x00 LCD_Line1W addlw 0x80 ;move to 1st row, column W call LCD_Cmd retlw 0x00 LCD_Line2W addlw 0xc0 ;move to 2nd row, column W call LCD_Cmd retlw 0x00 LCD_CurOn movlw 0x0d ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_CurOff movlw 0x0c ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_Clr movlw 0x01 ;Clear display call LCD_Cmd retlw 0x00 LCD_HEX movwf tmp1 swapf tmp1, w andlw 0x0f call HEX_Table call LCD_Char movf tmp1, w andlw 0x0f call HEX_Table call LCD_Char retlw 0x00 Delay255 movlw 0xff ;delay 255 mS goto d0 Delay100 movlw d'100' ;delay 100mS goto d0 Delay50 movlw d'50' ;delay 50mS goto d0 Delay20 movlw d'20' ;delay 20mS goto d0 Delay5 movlw 0x05 ;delay 5.000 ms (4 MHz clock) d0 movwf count1 d1 movlw 0xC7 ;delay 1mS movwf counta movlw 0x01 movwf countb Delay_0 decfsz counta, f goto $+2 decfsz countb, f goto Delay_0 decfsz count1 ,f goto d1 retlw 0x00 Pulse_e bsf LCD_PORT, LCD_E nop bcf LCD_PORT, LCD_E retlw 0x00 ;end of LCD routines HEX_Table ADDWF PCL , f RETLW 0x30 RETLW 0x31 RETLW 0x32 RETLW 0x33 RETLW 0x34 RETLW 0x35 RETLW 0x36 RETLW 0x37 RETLW 0x38 RETLW 0x39 RETLW 0x41 RETLW 0x42 RETLW 0x43 RETLW 0x44 RETLW 0x45 RETLW 0x46 Text addwf PCL, f retlw '1' retlw '6' retlw ' ' retlw 'B' retlw 'i' retlw 't' retlw ' ' retlw 'C' retlw 'o' retlw 'u' retlw 'n' retlw 't' retlw 'e' retlw 'r' retlw '.' retlw 0x00 ;This routine downloaded from http://www.piclist.com Convert: ; Takes number in NumH:NumL ; Returns decimal in ; TenK:Thou:Hund:Tens:Ones swapf NumH, w iorlw B'11110000' movwf Thou addwf Thou,f addlw 0XE2 movwf Hund addlw 0X32 movwf Ones movf NumH,w andlw 0X0F addwf Hund,f addwf Hund,f addwf Ones,f addlw 0XE9 movwf Tens addwf Tens,f addwf Tens,f swapf NumL,w andlw 0X0F addwf Tens,f addwf Ones,f rlf Tens,f rlf Ones,f comf Ones,f rlf Ones,f movf NumL,w andlw 0X0F addwf Ones,f rlf Thou,f movlw 0X07 movwf TenK ; At this point, the original number is ; equal to ; TenK*10000+Thou*1000+Hund*100+Tens*10+Ones ; if those entities are regarded as two's ; complement binary. To be precise, all of ; them are negative except TenK. Now the number ; needs to be normalized, but this can all be ; done with simple byte arithmetic. movlw 0X0A ; Ten Lb1: addwf Ones,f decf Tens,f btfss 3,0 goto Lb1 Lb2: addwf Tens,f decf Hund,f btfss 3,0 goto Lb2 Lb3: addwf Hund,f decf Thou,f btfss 3,0 goto Lb3 Lb4: addwf Thou,f decf TenK,f btfss 3,0 goto Lb4 retlw 0x00 end Tutorial 3.3 - requires Main Board and LCD Board.
;LCD 16 bit counter - using LCD Busy line ;Nigel Goodwin 2002 LIST p=16F628 ;tell assembler what chip we are using include "P16F628.inc" ;include the defaults for the chip ERRORLEVEL 0, -302 ;suppress bank selection messages __config 0x3D18 ;sets the configuration settings (oscillator type etc.) cblock 0x20 ;start of general purpose registers count ;used in looping routines count1 ;used in delay routine counta ;used in delay routine countb ;used in delay routine tmp1 ;temporary storage tmp2 templcd ;temp store for 4 bit mode templcd2 NumL ;Binary inputs for decimal convert routine NumH TenK ;Decimal outputs from convert routine Thou Hund Tens Ones endc LCD_PORT Equ PORTA LCD_TRIS Equ TRISA LCD_RS Equ 0x04 ;LCD handshake lines LCD_RW Equ 0x06 LCD_E Equ 0x07 org 0x0000 goto Start HEX_Table ADDWF PCL , f RETLW 0x30 RETLW 0x31 RETLW 0x32 RETLW 0x33 RETLW 0x34 RETLW 0x35 RETLW 0x36 RETLW 0x37 RETLW 0x38 RETLW 0x39 RETLW 0x41 RETLW 0x42 RETLW 0x43 RETLW 0x44 RETLW 0x45 RETLW 0x46 Text addwf PCL, f retlw '1' retlw '6' retlw ' ' retlw 'B' retlw 'i' retlw 't' retlw ' ' retlw 'C' retlw 'o' retlw 'u' retlw 'n' retlw 't' retlw 'e' retlw 'r' retlw '.' retlw 0x00 Start movlw 0x07 movwf CMCON ;turn comparators off (make it like a 16F84) Initialise clrf count clrf PORTA clrf PORTB clrf NumL clrf NumH SetPorts bsf STATUS, RP0 ;select bank 1 movlw 0x00 ;make all pins outputs movwf LCD_TRIS movwf TRISB bcf STATUS, RP0 ;select bank 0 call LCD_Init ;setup LCD clrf count ;set counter register to zero Message movf count, w ;put counter value in W call Text ;get a character from the text table xorlw 0x00 ;is it a zero? btfsc STATUS, Z goto NextMessage call LCD_Char incf count, f goto Message NextMessage movlw d'2' call LCD_Line2W ;move to 2nd row, third column call Convert ;convert to decimal movf TenK, w ;display decimal characters call LCD_CharD ;using LCD_CharD to convert to ASCII movf Thou, w call LCD_CharD movf Hund, w call LCD_CharD movf Tens, w call LCD_CharD movf Ones, w call LCD_CharD movlw ' ' ;display a 'space' call LCD_Char movf NumH, w ;and counter in hexadecimal call LCD_HEX movf NumL, w call LCD_HEX incfsz NumL, f goto Next incf NumH, f Next call Delay255 ;wait so you can see the digits change goto NextMessage ;Subroutines and text tables ;LCD routines ;Initialise LCD LCD_Init call LCD_Busy ;wait for LCD to settle movlw 0x20 ;Set 4 bit mode call LCD_Cmd movlw 0x28 ;Set display shift call LCD_Cmd movlw 0x06 ;Set display character mode call LCD_Cmd movlw 0x0c ;Set display on/off and cursor command call LCD_Cmd ;Set cursor off call LCD_Clr ;clear display retlw 0x00 ; command set routine LCD_Cmd movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bcf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high call LCD_Busy retlw 0x00 LCD_CharD addlw 0x30 ;add 0x30 to convert to ASCII LCD_Char movwf templcd swapf templcd, w ;send upper nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high movf templcd, w ;send lower nibble andlw 0x0f ;clear upper 4 bits of W movwf LCD_PORT bsf LCD_PORT, LCD_RS ;RS line to 1 call Pulse_e ;Pulse the E line high call LCD_Busy retlw 0x00 LCD_Line1 movlw 0x80 ;move to 1st row, first column call LCD_Cmd retlw 0x00 LCD_Line2 movlw 0xc0 ;move to 2nd row, first column call LCD_Cmd retlw 0x00 LCD_Line1W addlw 0x80 ;move to 1st row, column W call LCD_Cmd retlw 0x00 LCD_Line2W addlw 0xc0 ;move to 2nd row, column W call LCD_Cmd retlw 0x00 LCD_CurOn movlw 0x0d ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_CurOff movlw 0x0c ;Set display on/off and cursor command call LCD_Cmd retlw 0x00 LCD_Clr movlw 0x01 ;Clear display call LCD_Cmd retlw 0x00 LCD_HEX movwf tmp1 swapf tmp1, w andlw 0x0f call HEX_Table call LCD_Char movf tmp1, w andlw 0x0f call HEX_Table call LCD_Char retlw 0x00 Delay255 movlw 0xff ;delay 255 mS goto d0 Delay100 movlw d'100' ;delay 100mS goto d0 Delay50 movlw d'50' ;delay 50mS goto d0 Delay20 movlw d'20' ;delay 20mS goto d0 Delay5 movlw 0x05 ;delay 5.000 ms (4 MHz clock) d0 movwf count1 d1 movlw 0xC7 ;delay 1mS movwf counta movlw 0x01 movwf countb Delay_0 decfsz counta, f goto $+2 decfsz countb, f goto Delay_0 decfsz count1 ,f goto d1 retlw 0x00 Pulse_e bsf LCD_PORT, LCD_E nop bcf LCD_PORT, LCD_E retlw 0x00 LCD_Busy bsf STATUS, RP0 ;set bank 1 movlw 0x0f ;set Port for input movwf LCD_TRIS bcf STATUS, RP0 ;set bank 0 bcf LCD_PORT, LCD_RS ;set LCD for command mode bsf LCD_PORT, LCD_RW ;setup to read busy flag bsf LCD_PORT, LCD_E swapf LCD_PORT, w ;read upper nibble (busy flag) bcf LCD_PORT, LCD_E movwf templcd2 bsf LCD_PORT, LCD_E ;dummy read of lower nibble bcf LCD_PORT, LCD_E btfsc templcd2, 7 ;check busy flag, high = busy goto LCD_Busy ;if busy check again bcf LCD_PORT, LCD_RW bsf STATUS, RP0 ;set bank 1 movlw 0x00 ;set Port for output movwf LCD_TRIS bcf STATUS, RP0 ;set bank 0 return ;end of LCD routines ;This routine downloaded from http://www.piclist.com Convert: ; Takes number in NumH:NumL ; Returns decimal in ; TenK:Thou:Hund:Tens:Ones swapf NumH, w iorlw B'11110000' movwf Thou addwf Thou,f addlw 0XE2 movwf Hund addlw 0X32 movwf Ones movf NumH,w andlw 0X0F addwf Hund,f addwf Hund,f addwf Ones,f addlw 0XE9 movwf Tens addwf Tens,f addwf Tens,f swapf NumL,w andlw 0X0F addwf Tens,f addwf Ones,f rlf Tens,f rlf Ones,f comf Ones,f rlf Ones,f movf NumL,w andlw 0X0F addwf Ones,f rlf Thou,f movlw 0X07 movwf TenK ; At this point, the original number is ; equal to ; TenK*10000+Thou*1000+Hund*100+Tens*10+Ones ; if those entities are regarded as two's ; complement binary. To be precise, all of ; them are negative except TenK. Now the number ; needs to be normalized, but this can all be ; done with simple byte arithmetic. movlw 0X0A ; Ten Lb1: addwf Ones,f decf Tens,f btfss 3,0 goto Lb1 Lb2: addwf Tens,f decf Hund,f btfss 3,0 goto Lb2 Lb3: addwf Hund,f decf Thou,f btfss 3,0 goto Lb3 Lb4: addwf Thou,f decf TenK,f btfss 3,0 goto Lb4 retlw 0x00 end |