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Piclist Weedfreq 8DIGIT

The  Weeder Frequency Counter
Expanded by Brad Hernlem
3 byte count, 8 digits, 1Hz resolution below 16MHz
;******************************************************************************
;                           FREQUENCY COUNTER
;                           Model  : WTCNT
;                           Author : Terry J. Weeder
;                           Date   : November 18, 1993
;                           Version: 1.0
;
;                           WWW.WEEDTECH.COM
;
;                           Ported to 16f84 by
;                           Peter Cousens 
;                           October  1998
;
;                           Further revised,
;                           expanded and modified by
;                           Brad Hernlem
;                           October  2000
;******************************************************************************
; This version is changed to use the full capability to count to 3 byte
; quantities (16,777,215) and disables the overflow at 10,000,000 originally
; in Cousens' code. Also, 8 digits are used instead of seven and the gate
; times are set to 1 second to allow 1 Hz resolution on all ranges.
; When the frequency exceeds 16,777,215 Hz the gate period is 
; reduced to 0.1 second to keep the count within 3 bytes. When frequency is 
; again less than 16,777,216 Hz the gate period reverts to 1 second.
; Please also note that the register addresses are now designated in a 
; CBLOCK. This means that any changes to the CBLOCK MUST NOT affect the
; fixed addresses of the digs to digs+7 registers which SHOULD begin at
; 0C and increase from there. If these are changed, the FSR indirect 
; addressing will be munged.  
;
; Other changes:
;
; 1) the LCD control pins are reassigned to be compatible with Halicky's code
; 2) the display reads "0" when no pulses are inputted. Cousens' code included
;    an rtcc toggle of unknown use which gave an output of "1" without input.
; 3) display shows message "Counting" during initial 1 second count delay.
;
; [Brad Hernlem]
;
; FCounter.ASM
;***************************************************************************

        list    P=PIC16F84A
        INCLUDE <P16f84a.inc>						
	__CONFIG _CP_OFF & _WDT_OFF & _XT_OSC & _PWRTE_ON

rtcc    equ     1h

c       equ     0h
z       equ     2h
o       equ     7h

rs      equ     0h	;This bits were changed for compatibility
rw      equ     1h	;with other counter
e       equ     2h	;routines (e.g. Halicky)

;Cousens had the following hard designated. CBLOCK makes them float
;but BEWARE that digs is addressed by FSR and MUST NOT be changed from
;the first position of this block

	CBLOCK	h'0C'
digs:8 			;the display digits registers digs to digs+7
count1  
count2  
addcnt  
gate    
cnt1    
cnt2    
cnt3    
calc1   
calc2   
calc3   
sum1    
sum2    
sum3    
rtcc2
temp1
temp2 
temp3
cnt4 
	ENDC
;
        org     0
        goto    start
                        
;
int_del movlw   0x05            ;delay 5.000 ms (4 MHz clock)
        movwf   count1
d1      movlw   0xA5
        movwf   count2
d2      decfsz  count2,f
        goto    d2
        decfsz  count1,f
        goto    d1
        retlw   0x00
;
lcd_out movwf   PORTB          ;load data into PORTB
        movlw   b'00000000'     ;define PORTB as output
        tris    PORTB
        bsf     PORTA,rs       ;rs = data
        bcf     PORTA,rw       ;r/w = write
        bsf     PORTA,e        ;toggle enable
        bcf     PORTA,e
        movlw   b'11111111'     ;define PORTB as input
        tris    PORTB
        bcf     PORTA,rs       ;rs = instruction
        bsf     PORTA,rw       ;r/w = read
        bsf     PORTA,e        ;enable high
        movf    PORTB,w        ;get address counter
        movwf   addcnt
        bsf     addcnt,7
        bcf     PORTA,e        ;enable low
out1    bsf     PORTA,e        ;enable high
        btfss   PORTB,7        ;test busy flag
        goto    out2
        bcf     PORTA,e        ;enable low
        goto    out1
out2    bcf     PORTA,e        ;enable low
        goto    shift
;
inst    movwf   PORTB          ;load instruction into PORTB
        movlw   b'00000000'    ;define PORTB as output
        tris    PORTB
        bcf     PORTA,rs       ;rs = instruction
        bcf     PORTA,rw       ;r/w = write
        bsf     PORTA,e        ;toggle enable
        bcf     PORTA,e
        movlw   b'11111111'    ;define PORTB as input
        tris    PORTB
        bsf     PORTA,rw       ;r/w = read
inst1   bsf     PORTA,e        ;enable high
        btfss   PORTB,7        ;test busy flag
        goto    inst2
        bcf     PORTA,e        ;enable low
        goto    inst1
inst2   bcf     PORTA,e        ;enable low
        retlw   0x00
;
shift   btfss   addcnt,0        ;shift to opposite side of display?
        retlw   0x00
        btfss   addcnt,1
        retlw   0x00
        btfss   addcnt,2
        retlw   0x00
        btfss   addcnt,3
        retlw   0x00
        movlw   0x39
        addwf   addcnt,f
        bsf     addcnt,7
        movf    addcnt,w
        goto    inst
;
sub     bcf     STATUS,o        ;clear overflow bit
        movf    calc1,w         ;subtract calc1 from cnt1 
        subwf   cnt1,f
        btfsc   STATUS,c
        goto    sb1
        movlw   0x01            ;borrow from cnt2 if overflow
        subwf   cnt2,f
        btfsc   STATUS,c
        goto    sb1
        subwf   cnt3,f          ;borrow from cnt3 if cnt2 overflow
        btfss   STATUS,c
        bsf     STATUS,o        ;set overflow bit if result is negative
sb1     movf    calc2,w         ;subtract calc2 from cnt2
        subwf   cnt2,f
        btfsc   STATUS,c
        goto    sb2
        movlw   0x01            ;borrow from cnt3 if cnt2 overflow
        subwf   cnt3,f
        btfss   STATUS,c
        bsf     STATUS,o        ;set overflow bit if result is negative
sb2     movf    calc3,w         ;subtract calc3 from cnt3
        subwf   cnt3,f
        btfss   STATUS,c
        bsf     STATUS,o        ;set overflow bit if result is negative
        retlw   0x00
;
add     movf    calc1,w         ;add calc1 to cnt1
        addwf   cnt1,f
        btfss   STATUS,c
        goto    ad1
        incfsz  cnt2,f          ;add to cnt2 if cnt1 overflow
        goto    ad1
        incf    cnt3,f          ;add to cnt3 if cnt2 overflow
ad1     movf    calc2,w         ;add calc2 to cnt2
        addwf   cnt2,f
        btfsc   STATUS,c
        incf    cnt3,f          ;add to cnt3 if cnt2 overflow
        movf    calc3,w         ;add calc3 to cnt3
        addwf   cnt3,f
        retlw   0x00
;
; The following has been modified to extract 8 digits
; and get 1 Hz accuracy up to the full 3 byte limit of 16,777,215
;
cnvt    movlw   0x08            ;8 digits in display
        movwf   count1
        movlw   0x0C            ;set fsr for MSB in display
        movwf   FSR
        movlw   0x2F            ;one less that ASCII "0"
cnvt0   movwf   INDF
        incf    FSR,f
        decfsz  count1,f
        goto    cnvt0
        movlw   0x98		;load "10,000,000" in calc1-3
	movwf	calc3
	movlw	0x96
	movwf	calc2
	movlw	0x80
	movwf	calc1
cnvt1	call	sub		;subtract 10 million from count
	incf	digs,f		;increment 10,000,000s register
	btfss	STATUS,o	;check if overflow
	goto	cnvt1
	call	add		;add back last number
        movlw   0x0F            ;load "1,000,000" in calc1-3
        movwf   calc3
        movlw   0x42
        movwf   calc2
        movlw   0x40
        movwf   calc1
cnvt2   call    sub             ;subtract number from count
        incf    digs+1,f        ;increment 1,000,000's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt2
        call    add             ;add back last number
        movlw   0x01            ;load "100,000" in calc1-3
        movwf   calc3
        movlw   0x86
        movwf   calc2
        movlw   0xA0
        movwf   calc1
cnvt3   call    sub             ;subtract number from count
        incf    digs+2,f        ;increment 100,000's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt3
        call    add             ;add back last number
        clrf    calc3           ;load "10,000" in calc1-3
        movlw   0x27
        movwf   calc2
        movlw   0x10
        movwf   calc1
cnvt4   call    sub             ;subtract number from count
        incf    digs+3,f        ;increment 10,000's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt4
        call    add             ;add back last number
        movlw   0x03            ;load "1,000" in calc1-3
        movwf   calc2
        movlw   0xE8
        movwf   calc1
cnvt5   call    sub             ;subtract number from count
        incf    digs+4,f        ;increment 1,000's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt5
        call    add             ;add back last number
        clrf    calc2           ;load "100" in calc1-3
        movlw   0x64
        movwf   calc1
cnvt6   call    sub             ;subtract number from count
        incf    digs+5,f        ;increment 100's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt6
        call    add             ;add back number
        movlw   0x0A            ;load "10" in calc1-3
        movwf   calc1
cnvt7   call    sub             ;subtract number from count
        incf    digs+6,f        ;increment 10's register
        btfss   STATUS,o        ;check if overflow
        goto    cnvt7
        call    add             ;add back last number
        movf    cnt1,w          ;put remainder in 1's register
        addwf   digs+7,f
        incf    digs+7,f
        retlw   0x00
;
; Count period is 25*count2*count1 clocks
; for 4MHz crystal with count2=200, count1=20 gives 0.1 s gate period
;                                   count1=200 gives 1 s gate period
;
count   movlw   b'00110111'     ;rtcc = ext, 1/256
        option
        movlw   b'00010000'     ;define PORTA as output 
        tris    PORTA
        bcf     PORTA,3
        bcf     PORTA,rs
        clrf    cnt3
	clrf	cnt4
	clrf	temp3
        clrf    rtcc
        clrf    rtcc2
;        bsf     PORTA,rs        ;toggle rtcc pin
;        bcf     PORTA,rs	 ;[these two lines were in Cousens' code. purpose unkown]
        movf    gate,w          ;get gate time
        movwf   count1
st1     bsf     PORTA,3         ;start count
fr4     movlw   0xC8		;1  count2 set to 200
        movwf   count2		;2
        goto    fr6		;4
fr5     nop			;24
        nop			;25
        nop			;01
        nop			;02
        nop			;03
        nop			;04
fr6     movf    rtcc,w          ;5   test for rtcc rollover (12)
        subwf   rtcc2,f		;6
        btfss   STATUS,z	;7
        goto    fr7		;9
        nop			;9
        goto    fr8		;11
fr7     btfsc   STATUS,c	;10
        incf    cnt3,f		;11
fr8     movwf   rtcc2		;12
	movf	cnt3,w		;13 test for cnt3 rollover
	subwf	temp3,f		;14
	btfss	STATUS,z	;15
	goto	br1		;17
	nop			;17
	goto	br2		;19
br1	btfsc	STATUS,c	;18
	incf	cnt4,f		;19 increment cnt4 if cnt3 rollover
br2	movwf	temp3		;20
        decfsz  count2,f	;21
        goto    fr5		;23
        decfsz  count1,f	;23+25(count2-1)
        goto    fr4		;25
        bcf     PORTA,3         ;25*count2*count1  stop count
st2     movf    rtcc,w          ;get rtcc count
        movwf   cnt2
        subwf   rtcc2,f         ;test for rtcc rollover
        btfss   STATUS,c
        goto    fr9
        btfss   STATUS,z
        incf    cnt3,f
fr9     clrf    cnt1            ;set to get prescaler count
fr10    decf    cnt1,f
        bsf     PORTA,rs        ;toggle rtcc pin
        bcf     PORTA,rs
        movf    rtcc,w          ;test if rtcc has changed
        xorwf   cnt2,w
        btfsc   STATUS,z
        goto    fr10
        retlw   0x00
;
;******************************************************************************
;                                   START
;******************************************************************************
;
start   clrf    PORTA          ;instruction, write, enable low
        movlw   b'00010000'
        tris    PORTA
        clrf    PORTB
        movlw   b'00000000'
        tris    PORTB
        call    int_del
        call    int_del
        call    int_del
        movlw   0x38            ;initialize display
        movwf   PORTB
        bsf     PORTA,e        ;toggle enable
        call    int_del
        bcf     PORTA,e
        bsf     PORTA,e        ;toggle enable
        call    int_del
        bcf     PORTA,e
        bsf     PORTA,e        ;toggle enable
        call    int_del
        bcf     PORTA,e
        movlw   0x38            ;function
        call    inst
        movlw   b'00001100'     ;display on, cursor off
        call    inst
        movlw   b'00000001'     ;clear display
        call    inst
        movlw   b'00000110'     ;entry mode
        call    inst
;  Intro message during initial count 
        movlw   0x20		;space
	call	lcd_out
        movlw   0x20		;space
	call	lcd_out
        movlw   0x20		;space
	call	lcd_out
        movlw   0x20		;space
	call	lcd_out
        movlw   0x43		;C
	call	lcd_out
        movlw   0x6F		;0
	call	lcd_out
        movlw   0x75		;u
	call	lcd_out
        movlw   0x6E		;n
	call	lcd_out
        movlw   0x74		;t
	call	lcd_out
        movlw   0x69		;i
	call	lcd_out
        movlw   0x6E		;n
	call	lcd_out
        movlw   0x67		;g
	call	lcd_out
;
mhz     movlw   0xC8            ;1 sec gate
        movwf   gate
        call    count
	clrw			;check whether cnt4 is zero
	xorwf	cnt4,w
	btfss	STATUS,z
	goto	shortg		;not zero - use shorter gate period
        call    cnvt            ;convert binary to BCD
        movlw   0x30            ;test if "0"
        xorwf   digs,w
        btfss   STATUS,z
        goto    mhz1
        movlw   0x30            ;test if "0"
        xorwf   digs+1,w
        btfsc   STATUS,z
        goto    khz1
mhz1    movlw   0x81            ;set display address
        call    inst
        movlw   0x02            ;output first 2 characters
        movwf   count1
        movlw   0x0C            ;MSD of freq, i.e. digs
        movwf   FSR
mhz2    movlw   0x30            ;test if "0"
        xorwf   INDF,w
        btfss   STATUS,z
        goto    mhz3
        movlw   0x20            ;change preceeding "0's" to "space"
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    mhz2
        goto    mhz4
mhz3    movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    mhz3
mhz4    movlw   0x2E            ;"."
        call    lcd_out
        movlw   0x06            ;output last 6 characters
        movwf   count1  
mhz5    movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    mhz5
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x4D            ;"M"
        call    lcd_out
        movlw   0x48            ;"H"
        call    lcd_out
        movlw   0x7A            ;"z"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        goto    mhz
;
khz     movlw   0xC8            ;1 sec gate
        movwf   gate
        call    count
        call    cnvt            ;convert binary to BCD
        movlw   0x30            ;test if 0
        xorwf   digs,w
        btfss   STATUS,z
        goto    mhz1
        movlw   0x32            ;test if < 2
        subwf   digs+1,w
        btfsc   STATUS,c
        goto    mhz1
        movlw   0x30            ;test if "0"
        xorwf   digs+1,w
        btfss   STATUS,z
        goto    khz1
        movlw   0x30            ;test if "0"
        xorwf   digs+2,w
        btfss   STATUS,z
        goto    khz1
        movlw   0x30            ;test if "0"
        xorwf   digs+3,w
        btfsc   STATUS,z
        goto    hz0
khz1    movlw   0x81            ;set display address
        call    inst
        movlw   0x05            ;output first 5 characters
        movwf   count1
        movlw   0x0C            ;MSD of freq, digs register
        movwf   FSR
khz2    movlw   0x30            ;test if "0"
        xorwf   INDF,w
        btfss   STATUS,z
        goto    khz3
        movlw   0x20            ;change preceeding "0's" to "space"
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    khz2
        goto    khz4
khz3    movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    khz3
khz4    movlw   0x2E            ;"."
        call    lcd_out
        movf    INDF,w           ;output last 3 characters
        call    lcd_out
        incf    FSR,f
        movf    INDF,w
        call    lcd_out
        incf    FSR,f
        movf    INDF,w
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x4B            ;"K"
        call    lcd_out
        movlw   0x48            ;"H"
        call    lcd_out
        movlw   0x7A            ;"z"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        goto    khz
;
hz      movlw   0xC8            ;1 sec gate
        movwf   gate
        call    count
        call    cnvt            ;convert binary to BCD
        movlw   0x30            ;test if "0"
        xorwf   digs,w
        btfss   STATUS,z
        goto    mhz1
        movlw   0x32            ;test if < 2
        subwf   digs+1,w
        btfsc   STATUS,c
        goto    mhz1
        movlw   0x30            ;test if "0"
        xorwf   digs+1,w
        btfss   STATUS,z
        goto    khz1
        movlw   0x30            ;test if "0"
        xorwf   digs+2,w
        btfss   STATUS,z
        goto    khz1
        movlw   0x30            ;test if "0"
        xorwf   digs+3,w
        btfss   STATUS,z
        goto    khz1
hz0     movlw   0x81            ;set display address
        call    inst
        movlw   0x07            ;output first 7 characters
        movwf   count1
        movlw   0x0C            ;MSD of freq, digs register
        movwf   FSR
hz1     movlw   0x30            ;test if "0"
        xorwf   INDF,w
        btfss   STATUS,z
        goto    hz2
        movlw   0x20            ;change preceeding "0's" to "space"
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    hz1
        goto    hz3
hz2     movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    hz2
hz3	movf	INDF,w
	call	lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x48            ;"H"
        call    lcd_out
        movlw   0x7A            ;"z"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        goto    hz
;
shortg  movlw   0x14            ;0.1 sec gate
        movwf   gate
        call    count
	call	tenx		;multiply count by ten
	clrw			;check whether cnt4 is zero
	xorwf	cnt4,w
	btfsc	STATUS,z
	goto	mhz		;was zero - use longer gate period
        call    cnvt            ;convert binary to BCD
        movlw   0x30            ;test if "0"
        xorwf   digs,w
        btfss   STATUS,z
        goto    shg1
        movlw   0x30            ;test if "0"
        xorwf   digs+1,w
        btfsc   STATUS,z
        goto    mhz
shg1    movlw   0x81            ;set display address
        call    inst
        movlw   0x03            ;output first 3 characters
        movwf   count1
        movlw   0x0C            ;MSD of freq, i.e. digs
        movwf   FSR
shg2    movlw   0x30            ;test if "0"
        xorwf   INDF,w
        btfss   STATUS,z
        goto    shg3
        movlw   0x20            ;change preceeding "0's" to "space"
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    shg2
        goto    shg4
shg3    movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    shg3
shg4    movlw   0x2E            ;"."
        call    lcd_out
        movlw   0x05            ;output last 5 characters
        movwf   count1  
shg5    movf    INDF,w
        call    lcd_out
        incf    FSR,f
        decfsz  count1,f
        goto    shg5
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x4D            ;"M"
        call    lcd_out
        movlw   0x48            ;"H"
        call    lcd_out
        movlw   0x7A            ;"z"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        movlw   0x20            ;"space"
        call    lcd_out
        goto    shortg
;
; This subroutine multiplies the count in cnt1-3 by 10 (called from the 0.1 sec
; gate routine) and puts any overflow into cnt4. This is to check whether the frequency
; has gone back under 16,777,216 and whether the gate period should be increased to 1 sec.
;
tenx	clrf	cnt4		;clear the overflow register and
	movf	cnt1,w		;fill calc1-3 with current cnt1-3 values
	movwf	calc1		;it is assumed that cnt4 cannot be non-zero
	movf	cnt2,w		;when the gate period is only 0.1 sec
	movwf	calc2		;
	movf	cnt3,w		;
	movwf	calc3		;
	bcf	STATUS,c
	rlf	calc1,f		;multiply by 2 and carry through
	rlf	calc2,f
	rlf	calc3,f
	btfsc	STATUS,c
	incf	cnt4,f		
	movf	calc1,w		;temporarily store the times 2 value
	movwf	temp1
	movf	calc2,w
	movwf	temp2
	movf	calc3,w
	movwf	temp3
	bcf	STATUS,c
	rlf	calc1,f		;multiply by 2 twice and check for carry each time
	rlf	calc2,f
	rlf	calc3,f
	btfsc	STATUS,c
	incf	cnt4,f
	bcf	STATUS,c
	rlf	calc1,f
	rlf	calc2,f
	rlf	calc3,f
	btfsc	STATUS,c
	incf	cnt4,f
	movf	temp1,w		;now add the x2 and x8 values for x10 total
	addwf	calc1,f
	btfsc	STATUS,c
	incf	calc2, f
	btfsc	STATUS,z
	incf	calc3,f
	btfsc	STATUS,z
	incf	cnt4,f
	movf	temp2,w
	addwf	calc2,f
	btfsc	STATUS,c
	incf	calc3,f
	btfsc	STATUS,z
	incf	cnt4,f
	movf	temp3,w
	addwf	calc3,f
	btfsc	STATUS,c
	incf	cnt4,f
	return
;
        end



file: /Techref/piclist/weedfreq/8digit.asm, 22KB, , updated: 2006/4/7 13:43, local time: 2018/1/23 08:14,
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