;PICGN220.ASM 21APR00 - JOHN BECKER - EPE PIC FUNCTION GEN + FREQ COUNT

;PIC16F877-4, 3.2768Hz, WDT OFF, POR ON, XTAL XT

;Config register bits (all PIC TOOLKIT MK2 defaults)
; CP1 CP0 DBG NIL WRT CPD LVP BOR CP1 CP0 POR WDT OS1 OS0
;  1   1   1   1   1   1   0   0   1   1   0   0   0   1
;N.B. Logic 1/0 do NOT necessarily mean that the function is On/Off
;respectively - refer to PIC '87 data sheet.

#DEFINE PAGE0   BCF $03,5
#DEFINE PAGE1   BSF $03,5

INDF:    .EQU $00  ;page 0, 1, 2, 3
TMR0:    .EQU $01  ;page 0, 2
OPTION:  .EQU $01  ;page 1, 3
PCL:     .EQU $02  ;page 0, 1, 2, 3
STATUS:  .EQU $03  ;page 0, 1, 2, 3
FSR:     .EQU $04  ;page 0, 1, 2, 3

PORTA:   .EQU $05  ;page 0
TRISA:   .EQU $05  ;page 1
PORTB:   .EQU $06  ;page 0, 2
TRISB:   .EQU $06  ;page 1, 3
PORTC:   .EQU $07  ;page 0
TRISC:   .EQU $07  ;page 1
PORTD:   .EQU $08  ;page 0
TRISD:   .EQU $08  ;page 1
PORTE:   .EQU $09  ;page 0
TRISE:   .EQU $09  ;page 1

INTCON:  .EQU $0B  ;page 0, 1, 2, 3
ADCON0:  .EQU $1F  ;page 0
ADCON1:  .EQU $1F  ;page 1

LOOPA:   .EQU $20       ;loop used by LCD send routine
LOOPB:   .EQU $21       ;general loop
STORE:   .EQU $22       ;general store
STORE1:  .EQU $23       ;general store
STORE2:  .EQU $24       ;general store
STORE3:  .EQU $25       ;general store
RSLINE:  .EQU $26       ;LCD function flag store
SWITCH:  .EQU $27       ;switch status store
MARK1:   .EQU $28       ;freq count polarity marker 1
MARK2:   .EQU $29       ;freq count polarity marker 2

DEC1:    .EQU $2A       ;decimalisation byte 1
DEC2:    .EQU $2B       ; byte 2
DEC3:    .EQU $2C       ; byte 3
DEC4:    .EQU $2D       ; byte 4
DEC5:    .EQU $2E       ; byte 5
DEC6:    .EQU $2F       ; byte 6 (dummy)      

ANSA1:   .EQU $30       ;decimalisation answer store 1
ANSA2:   .EQU $31       ; answer 2
ANSA3:   .EQU $32       ; answer 3
ANSA4:   .EQU $33       ; answer 4
ANSA5:   .EQU $34       ; answer 5

FREQ0:   .EQU $35       ;frequency counter lsb
FREQ1:   .EQU $36       ;frequency counter nsb
FREQ2:   .EQU $37       ;frequency counter nsb
FREQ3:   .EQU $38       ;frequency counter nsb
FREQ4:   .EQU $39       ;frequency counter msb
CLKCNT:  .EQU $3A       ;timing counter
SLOWIT:  .EQU $3B       ;delay factor for PAUSE
LOOPX:   .EQU $3C       ;delay loop for LCDOUT

OUT7:    .EQU $3D       ;8 bytes for freq store and output to LCD
OUT6:    .EQU $3E
OUT5:    .EQU $3F
OUT4:    .EQU $40
OUT3:    .EQU $41
OUT2:    .EQU $42
OUT1:    .EQU $43
OUT0:    .EQU $44
LCDSTOR1: .EQU $45
LCDSTOR2: .EQU $46
STOREC:   .EQU $47
STORED:   .EQU $48
TENFLG:   .EQU $49
TENCNT:   .EQU $4A
RANGE:    .EQU $4B      ;frequency cap selection
SHAPE:    .EQU $4C      ;waveform shape selection
SAMPLE:   .EQU $4D      ;1sec/10sec flag
CLKVAL1:  .EQU $4E
CLKVAL2:  .EQU $4F

                    ;extends to $7F (max limit)

W:       .EQU 0
F:       .EQU 1
C:       .EQU 0
DC:      .EQU 1
Z:       .EQU 2

RP0:     .EQU 5         ;STATUS reg
RP1:     .EQU 6         ;STATUS reg
GIE:     .EQU 7         ;INTCON reg


        .ORG $0004      ;Interrupt vector address
        GOTO START      ;Jump to interrupt routine on interrupt
        .ORG $0005      ;Start of program memory

        clrf INTCON

GIEOFF: BCF INTCON,GIE  ;turn off global interrupts
        BTFSC INTCON,GIE
        goto GIEOFF

        goto START

TABLCD: addwf PCL,F     ;LCD initialisation table
        retlw %00110011 ;initialise lcd - first byte
        retlw %00110011 ;2nd byte (repeat of first)
        retlw %00110010 ;set for 4-bit operation
        retlw %00101100 ;set for 2 lines
        retlw %00000110 ;set entry mode to increment each address
        retlw %00001100 ;set display on, cursor off, blink off
        retlw %00000001 ;clear display
        retlw %00000010 ;return home, cursor & RAM to zero
                        ;end initialisation table

TBDEC1:                 ;table for decimalisation lsb
        addwf PCL,F     ;add program counter
        retlw $10       ;lsb of 10000
        retlw $E8       ;lsb of 1000
        retlw $64       ;lsb of 100
        retlw $0A       ;lsb of 10

TBDEC2:                 ;table for decimalisation msb
        addwf PCL,F     ;add program counter
        retlw $27       ;msb of 10000
        retlw $03       ;msb of 1000
        retlw 0         ;msb of 100
        retlw 0         ;msb of 10

RANGIT: addwf PCL,F     ;range control vals
        retlw %11111111
        retlw %11111101
        retlw %11111011
        retlw %11110111
        retlw %11101111
        retlw %11011111
        retlw %10111111
        retlw %01111111

WAVEIT: addwf PCL,F     ;waveform message routing
        goto SQUARE
        goto TRNGLE
        goto SINE

SINE:   movf LOOPA,W
        addwf PCL,F     ;sine message route
        retlw 'S'
        retlw 'I'
        retlw 'N'
        retlw 'E'

SQUARE: movf LOOPA,W
        addwf PCL,F     ;square message route
        retlw 'S'
        retlw 'Q'
        retlw 'R'
        retlw ' '

TRNGLE: movf LOOPA,W
        addwf PCL,F     ;triangle message route
        retlw 'T'
        retlw 'R'
        retlw 'I'
        retlw ' '

;..............

START:  bcf STATUS,RP0
        bcf STATUS,RP1
        clrf PORTA
        clrf PORTB
        clrf PORTC
        clrf PORTD
        clrf PORTE
        PAGE1
        clrf TRISA          ;PORTA as output
        movlw %00111111
        movwf TRISB         ;PORTB as input
        movlw 255
        movwf TRISC         ;PORTC as input
        movlw %11001111
        movwf TRISD         ;RD0-RD3, RD6-RD7 as input, RD4-RD5 as output
        movlw %00000111
        movwf TRISE         ;PORTE as input
        movlw %00000111     ;set LHS justify, RA0-RA3 as digital
        movwf ADCON1
        movlw %10000110     ;PORTB pullups off, timer 1:128 (1/25th sec)
        movwf OPTION
        PAGE0

        call PAUSIT
LCDSET: clrf LOOPB
        clrf RSLINE
LCDST2: movf LOOPB,W
        call TABLCD
        call LCDOUT
        incf LOOPB,F
        btfss LOOPB,3
        goto LCDST2
        call PAUSIT

         clrf MARK2
         clrf SWITCH
         clrf FREQ0
         clrf FREQ1
         clrf FREQ2
         clrf FREQ3
         clrf FREQ4
         clrf ANSA1
         clrf ANSA2
         clrf ANSA3
         clrf ANSA4
         clrf ANSA5
         clrf DEC1
         clrf DEC2
         clrf DEC3
         clrf DEC4
         clrf DEC5
         clrf DEC6
         clrf TENFLG
         clrf TENCNT
         clrf MARK1
         clrf MARK2
         clrf RANGE
         clrf SAMPLE
         movlw 0               ;......2
         movwf SHAPE
         call WAVE1
         movlw 25
         movwf CLKVAL1
         movlw 250
         movwf CLKVAL2

         movf CLKVAL1,W
         movwf CLKCNT

         bsf PORTD,4        ;reset counter IC6
         bcf PORTD,4
         bsf PORTD,5        ;enable clock input

         movlw 4
         movwf RANGE
         bcf INTCON,2

         goto SHWRNG

;............................ END OF SETUP

MAIN:    btfss INTCON,2
         goto MF1
         bcf INTCON,2

         movf PORTE,W       ;is a range switch pressed?
         btfss STATUS,Z
         goto RANGESW       ;yes
         btfsc PORTB,0      ;is waveshape switch pressed?
         call WAVEFRM       ;yes
         decfsz CLKCNT,F    ;dec timing counter, is it 0
         goto MF1           ;no
         goto GETFREQ       ;yes

MF1:     call INCCNT
         goto MAIN


INCCNT:  btfss PORTC,0
         goto MF2
         bsf MARK2,0
         return

MF2:     btfss MARK2,0      ;is MARK2 = 1?
         return             ;no
         bcf MARK2,0
         incfsz FREQ2,F     ;yes, inc counters accordingly
         return             ;(responds to negative-going aspect of IC6 Q12)
         incfsz FREQ3,F
         return
         incf FREQ4,F
         return

;............show freq routine

GETFREQ: bcf PORTD,5        ;turn off clock input
         nop
         nop
         call INCCNT        ;*****
         movf PORTD,W       ;get pins which include Q0-Q3
         movwf STORED
         movf PORTC,W
         movwf STOREC
         bsf PORTD,5        ;turn on clock input

         bcf STATUS,C       ;shift freq counters right by 4 places
         rrf FREQ4,F
         rrf FREQ3,F
         rrf FREQ2,F
         rrf FREQ1,F
         bcf STATUS,C
         rrf FREQ4,F
         rrf FREQ3,F
         rrf FREQ2,F
         rrf FREQ1,F
         bcf STATUS,C
         rrf FREQ4,F
         rrf FREQ3,F
         rrf FREQ2,F
         rrf FREQ1,F
         bcf STATUS,C
         rrf FREQ4,F
         rrf FREQ3,F
         rrf FREQ2,F
         rrf FREQ1,F

         btfsc STORED,1     ;Q1
         bsf FREQ0,0
         btfsc STORED,2     ;Q2
         bsf FREQ0,1
         btfsc STORED,3     ;Q3
         bsf FREQ0,2
         btfsc STOREC,4     ;Q4
         bsf FREQ0,3
         btfsc STOREC,6     ;Q5
         bsf FREQ0,4
         btfsc STOREC,7     ;Q6
         bsf FREQ0,5
         btfsc STOREC,5     ;Q7
         bsf FREQ0,6
         btfsc STOREC,3     ;Q8
         bsf FREQ0,7

         btfsc STORED,0     ;Q9
         bsf FREQ1,0
         btfsc STOREC,2     ;Q10
         bsf FREQ1,1
         btfsc STOREC,1     ;Q11
         bsf FREQ1,2
         btfsc STOREC,0     ;Q12
         bsf FREQ1,3

         movlw FREQ0
         call DECIML        ;decimalise digits 1 to 4 
         movf DEC1,W        ;copy answer into OUT-OUT3
         movwf OUT0
         movf ANSA1,W
         movwf OUT1
         movf ANSA2,W
         movwf OUT2
         movf ANSA3,W
         movwf OUT3

GF3:     movf ANSA4,W       ;copy overflow val into prev freq positions
         movwf FREQ0
         movf ANSA5,W
         movwf FREQ1
         clrf FREQ2
         clrf FREQ3
         clrf FREQ4
         movlw FREQ0
         call DECIML        ;now decimal digits 5 to 8

         movf ANSA3,W       ;copy answer into OUT4 to OUT7
         movwf OUT7
         movf ANSA2,W
         movwf OUT6
         movf ANSA1,W
         movwf OUT5
         movf DEC1,W
         movwf OUT4

GF4:     call LCD5          ;output freq data to LCD
         bsf RSLINE,4
         clrf MARK1         ;clear leading zero flag

         movlw OUT7
         movwf FSR
         movlw 8
         movwf LOOPA
MAINA:   movf INDF,W
         btfss STATUS,Z     ;is val = 0?
         goto MAINB         ;no
         btfsc MARK1,0      ;has val >0 been output?
         goto MAINB         ;yes
         movf LOOPA,W       ;is it the last byte of the loop?
         xorlw 1
         btfsc STATUS,Z
         goto MAINB         ;yes
         movlw ' '          ;clear leading zero
         goto MAINC

MAINB:   bsf MARK1,0        ;format as ASCII decimal val
         andlw 15
         iorlw 48

MAINC:   call LCDOUT
         incf FSR,F
         decfsz LOOPA,F
         goto MAINA
         btfss SAMPLE,0
         goto GF5
         call LCD12
         bsf RSLINE,4
         movlw '.'
         call LCDOUT

         decf FSR,F
         movf INDF,W
         andlw 15
         iorlw 48
         call LCDOUT
         goto GF6

GF5:     movlw ' '
         call LCDOUT

GF6:     movlw 'H'
         call LCDOUT
         movlw 'z'
         call LCDOUT

MAINX:   clrf FREQ0         ;clear freq counters
         clrf FREQ1
         clrf FREQ2
         clrf FREQ3
         clrf FREQ4
         clrf MARK2

         movf CLKVAL1,W
         btfsc SAMPLE,0     ;is 10sec rate on?
         movf CLKVAL2,W
         movwf CLKCNT
         bsf PORTD,4        ;reset counter IC6
         bcf PORTD,4
         bsf PORTD,5        ;enable clock input

         clrf TMR0
         bcf INTCON,2       ;clear interrupt

         goto MAIN          ;start sampling next batch

;.............

PAUSIT:  movlw 7
         movwf SLOWIT
         bcf INTCON,2
PAUSE:   btfss INTCON,2
         goto PAUSE
         bcf INTCON,2
         decfsz SLOWIT,F
         goto PAUSE
         return

;................

LCD1:    movlw %10000000     ;LCD cell position codes - not all used
         goto LCDLIN
LCD5:    movlw %10000101
         goto LCDLIN
LCD6:    movlw %10000110
         goto LCDLIN
LCD7:    movlw %10000111
         goto LCDLIN

LCD9:    movlw %10001001
         goto LCDLIN
LCD12:   movlw %10001100
         goto LCDLIN

LCD21:   movlw %11000000
         goto LCDLIN
LCD24:   movlw %11000100
         goto LCDLIN
LCD25:   movlw %11000101
         goto LCDLIN
LCD26:   movlw %11000110
         goto LCDLIN
LCD27:   movlw %11000111
         goto LCDLIN

LCD28:   movlw %11001000
         goto LCDLIN
LCD29:   movlw %11001001
         goto LCDLIN

LCDLIN:  BCF RSLINE,4

LCDOUT:  movwf STORE
         movlw 50
         movwf LOOPX
DELAY:   decfsz LOOPX,F
         goto DELAY
         call SENDIT
SENDIT:  swapf STORE,F
         movf STORE,W
         andlw 15
         iorwf RSLINE,W
         movwf LCDSTOR1
         clrf LCDSTOR2
         movlw 6
         movwf LOOPX

SHIFT:   bcf STATUS,C      ;rearrange bits to suit PORTA pin order
         rrf LCDSTOR1,F
         rlf LCDSTOR2,F
         decfsz LOOPX,F
         goto SHIFT
         movf LCDSTOR2,W
         movwf PORTA
         bsf PORTA,0       ;toggle LCD line E
         bcf PORTA,0
         bsf PORTA,5       ;turn on IC2 sync output line
         return

;..............convert binary to hex - not used in final model

LCDHEX: movwf STORE2    ;split & format decimal byte as HEX for LCD
        swapf STORE2,W  ;get tens nibble
        andlw 15
        movwf STORE1
        addlw 6
        btfss STATUS,DC
        goto HEX2
        movf STORE1,W
        addlw 55        ;set as alpha
        goto HEX3
HEX2:   movf STORE1,W
        iorlw 48        ;set as numeral
HEX3:   call LCDOUT     ;send it
        movf STORE2,W   ;get units
        andlw 15
        movwf STORE1
        addlw 6
        btfss STATUS,DC
        goto HEX4
        movf STORE1,W
        addlw 55        ;set as alpha
        goto HEX5
HEX4:   movf STORE1,W
        iorlw 48        ;set as numeral
HEX5:   call LCDOUT
        return

;........... used to convert binary bytes to decimal for LCD

DECIML:                 ;decimalise binary number
                        ;copy source into working area at DEC
                        ;source address is brought in on W
                        ;DEC1-5 becomes source
                        ;answer goes into ANSA
        call COPYFD     ;copy data at FSR into DEC
        clrf STORE1
        clrf STORE3
        clrf ANSA5
        movlw ANSA4     ;set answer store address
        movwf FSR
        clrf LOOPA

DCML0:  movf LOOPA,W
        call TBDEC1     ;subtract lsb from source value
        subwf DEC1,F
        btfsc STATUS,C  ;is there a borrow?
        goto DCML1      ;no, so sub msb
        movlw 1
        subwf DEC2,F    ;yes so decrement next byte
        btfsc STATUS,C  ;is there a borrow?
        goto DCML1      ;no, so sub msb
        movlw 1         ;yes
        subwf DEC3,F
        btfsc STATUS,C  ;is there a borrow?
        goto DCML1      ;no, so sub msb
        movlw 1         ;yes
        subwf DEC4,F
        btfsc STATUS,C  ;is there a borrow?
        goto DCML1      ;no, so sub msb
        movlw 1         ;yes
        subwf DEC5,F
        btfsc STATUS,C  ;is there a borrow?
        goto DCML1      ;no, so sub msb

DCML3:  movf LOOPA,W    ;yes, so re-add last table values lsb
        call TBDEC1
        addwf DEC1,F
        btfss STATUS,C  ;is there a carry?
        goto DCML5      ;no so exit loop
        incf DEC2,F     ;yes so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML5      ;no so exit loop
        incf DEC3,F     ;yes
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML5      ;no so exit loop
        incf DEC4,F     ;yes
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML5      ;no so exit loop
        incf DEC5,F     ;yes
        goto DCML5      ;exit loop

DCML1:  movf LOOPA,W
        call TBDEC2     ;subtract msb from source value
        subwf DEC2,F
        btfsc STATUS,C  ;is there a borrow?
        goto DCML2      ;no
        movlw 1
        subwf DEC3,F    ;yes so decrement next byte
        btfsc STATUS,C  ;is there a borrow?
        goto DCML2      ;no
        movlw 1
        subwf DEC4,F    ;yes so decrement next byte
        btfsc STATUS,C  ;is there a borrow?
        goto DCML2      ;no
        movlw 1
        subwf DEC5,F    ;yes so decrement next byte
        btfss STATUS,C  ;is there a borrow?
        goto DCML4      ;yes

DCML2:  incfsz STORE1,F ;inc counter & continue looping till zero
        goto DCML0
        incf STORE3,F
        goto DCML0

DCML4:  movf LOOPA,W    ;re-add last table values lsb
        call TBDEC1
        addwf DEC1,F
        btfss STATUS,C  ;is there a carry?
        goto DCML4A     ;no so add msb
        incf DEC2,F     ;yes so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML4A     ;no so add msb
        incf DEC3,F     ;yes, so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML4A     ;no so add msb
        incf DEC4,F     ;yes, so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML4A     ;no so add msb
        incf DEC5,F     ;yes, so inc next byte

DCML4A: movf LOOPA,W    ;re-add last table values msb
        call TBDEC2
        addwf DEC2,F
        btfss STATUS,C  ;is there a carry?
        goto DCML5      ;no
        incf DEC3,F     ;yes, so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML5      ;no
        incf DEC4,F     ;yes, so inc next byte
        btfss STATUS,Z  ;is there a carry? (is it zero)
        goto DCML5      ;no
        incf DEC5,F     ;yes, so inc next byte

DCML5:  movf STORE3,W
        btfss STATUS,Z
        movwf ANSA5
        movf STORE1,W   ;store counter and loop for next values
        movwf INDF      ;INDF here is ANSA group

        clrf STORE1
        clrf STORE3
        decf FSR,F

        incf LOOPA,F
        btfss LOOPA,2   ;is it = 4?
        goto DCML0      ;no

DCML6:  return

COPYFD: movwf FSR       ;copy data at FSR to DEC
        movf INDF,W
        movwf DEC1
        incf FSR,F
        movf INDF,W
        movwf DEC2
        incf FSR,F
        movf INDF,W
        movwf DEC3
        incf FSR,F
        movf INDF,W
        movwf DEC4
        incf FSR,F
        movf INDF,W
        movwf DEC5
        clrf DEC6
        return

;...........range switch

RANGESW:  btfsc PORTE,2
          goto SAMRATE
          call OK

          btfsc PORTE,1
          goto DECRNG

INCRNG:   incf RANGE,W
          goto SHWRNG
DECRNG:   decf RANGE,W

SHWRNG:   andlw 7
          movwf RANGE
          call LCD21
          bsf RSLINE,4
          movlw 'R'
          call LCDOUT
          movlw 'a'
          call LCDOUT
          movlw 'n'
          call LCDOUT
          movlw 'g'
          call LCDOUT
          movlw 'e'
          call LCDOUT

          movf RANGE,W
          sublw 7

          iorlw 48
          call LCDOUT
          movf PORTB,W
          andlw %11000000
          movwf PORTB

          bcf PORTD,6
          bcf PORTD,7

          movf RANGE,W
          call RANGIT
          andlw %00111111
          PAGE1
          movwf TRISB
          PAGE0
          movf RANGE,W
          call RANGIT
          andlw %11000000
          iorlw %00001111
          PAGE1
          movwf TRISD
          PAGE0
          call PAUSIT
          call PAUSIT
          movf PORTE,W
          andlw 3
          btfss STATUS,Z
          goto RANGESW
          goto SAM1

;...........set sample rate 1sec/10sec

SAMRATE: incf SAMPLE,F
         bcf SAMPLE,1
         call OK

SAM1:    clrf FREQ0         ;clear freq counters
         clrf FREQ1
         clrf FREQ2
         clrf FREQ3
         clrf FREQ4
         clrf MARK2

          call LCD27
          bsf RSLINE,4
          movlw 'T'
          call LCDOUT
          movlw 'i'
          call LCDOUT
          movlw 'm'
          call LCDOUT
          movlw 'e'
          call LCDOUT
          movlw '1'
          call LCDOUT
          movlw ' '
          btfsc SAMPLE,0
          movlw '0'
          call LCDOUT
          movlw 's'
          call LCDOUT
          movlw 'e'
          call LCDOUT
          movlw 'c'
          call LCDOUT

SAM3:    movf PORTE,W
         andlw 7
         btfss STATUS,Z
         goto SAM3

         call LCD5          ;output freq data to LCD
         bsf RSLINE,4
          movlw ' '
          call LCDOUT
          movlw ' '
          call LCDOUT
          movlw 'C'
          call LCDOUT
          movlw 'O'
          call LCDOUT
          movlw 'U'
          call LCDOUT
          movlw 'N'
          call LCDOUT
          movlw 'T'
          call LCDOUT
          movlw 'I'
          call LCDOUT
          movlw 'N'
          call LCDOUT
          movlw 'G'
          call LCDOUT
          movlw ' '
          call LCDOUT

         movf CLKVAL1,W
         btfsc SAMPLE,0
         movf CLKVAL2,W
         movwf CLKCNT
 
         bsf PORTD,4        ;reset counter IC6
         bcf PORTD,4

         goto MAIN

OK:      call LCD5          ;output freq data to LCD
         bsf RSLINE,4
         movlw ' '
         call LCDOUT
         movlw ' '
         call LCDOUT
         movlw 'O'
         call LCDOUT
         movlw 'K'
         call LCDOUT

         movlw 7
         movwf LOOPA
OK2:     movlw ' '
         call LCDOUT
         decfsz LOOPA,F
         goto OK2
         movlw '0'
         call LCDOUT
         return

;........

WAVEFRM: incf SHAPE,F
         movf SHAPE,W
         xorlw %00000011
         btfsc STATUS,Z
         clrf SHAPE

WAVE1:   call LCD1          ;output freq data to LCD
         bsf RSLINE,4
         clrf LOOPA
WAVE2:   movf SHAPE,W
         call WAVEIT
         call LCDOUT
         incf LOOPA,F
         btfss LOOPA,2
         goto WAVE2

         swapf SHAPE,W
         movwf STORE
         rlf STORE,F
         rlf STORE,W
         andlw %11000000
         movwf STORE
         movf PORTB,W
         andlw %00111111
         iorwf STORE,W
         movwf PORTB

WAVE3:   btfsc PORTB,0
         goto WAVE3
         call PAUSIT
         return

         .END