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LED light-emitting diode
> | http://
>
> 2000
>
> ---------------------------------------------------------
>
> 7LED frequency meter total 35MHz. The decimal point is after MHz digit, but can be set at any position. Two dots can be set too (timing formula will change!).
>
> Power consumption: 2.5V/9mA, 3V/13mA, 5V/35mA.
>
> Hardware:
> :PIC16F84
> 4051 (BCD->1of8 decoder)
> 8 NPN triodes,
> 7 LED (total),
> some resistors, capacitors and 2 switching diodes
>
> Note:
> "Calculator display" means (say) 7-digit LED multiplexed display.
> Both common cathode and common anode can be used. Software is written for both. For common anode displays it requires very slight software (uncomment what is commented and comment what isn't...;-) and hardware modification (switching transistors are PNP instead of NPN, the resistors are connected with +5V and also PIN No. 3 of 4051 should be grounded).
>
> PIC is used as 3-byte counter. If it counts 0.1s maximum measured frequency is FFFFFF, e.g. 167.77215MHz (theoretically).
>
> In reality the maximum measured frequency will not exceed 50MHz what is maximum input frequency of PIC precounter. But real one is around 27MHz and with 1/6 of 74HC14 (Schmitt trigger) up to 38MHz.
>
> +-++-+
> ||||||
> ||470||470|||
> |||||||
> ||+-++---\+-+|
> |RA4|+------+|||||
> |RA3|--|470|-+--|+0-+-\|
> |RA2|+------+||\|___|
> |------++---//||
> |V|
> |||
> |---|
> ---------------------------------------------------------
>
> The scale uses internal prescaler of PIC as low byte of counter, TMR0 as middle byte and some register as high byte of counter. The software DOESN'T read anything from any input port. RA4 is used as prescaler input.
>
> ---------------------------------------------------------
>
> Measuring period is 100000us.
> Processor cycle is T=4/Fx us [MHz], fx is Xtal frequency
>
> Number of processor cycles per measuring period:
>
> N=100000/T processor cycles
> N=Fx*100000/4=25000*Fx
>
> The main steps of measuring period:
>
> 1. start measurement,
> 2. precode decimal value of digit to segments,
> 3. if it's 5th digit set decimal point,
> 4. output to Port B,
> 5. output digit number to Port A
> (numbers from left to right are 6543210),
> 6. test TMR0 overflow bit, if YES increase Timer H,
> 7. leave digit to light,
> 8. increase digit number,
> 9. if <7 goto 2,
> 10. else zero digit number, decrease counter and go to 2,
> 11. stop measurement,
> 12. shift out precounter content,
> 13. in case of digital scale add/subtract RF,
> 14. precode 3-byte value into 7 decimal numbers,
> 15. go to 1
>
> ---------------------------------------------------------
>
> Total timing formula:
>
> N=25000*Fx=60*[7*(36+3*T1)+6+3*T2]+12+3*T3+Z
>
> where T1, T2, T3 are initial values of timing loops,
> Z are additional tuning NOPs,
> Fx Xtal frequency in MHz.
>
> ---------------------------------------------------------
>
> Some ideas were taken from "Simple low-cost digital frequency meter using a PIC16C54" (frqmeter.asm)
> written by James Hutchby, MadLab Ltd. 1996
>
> ---------------------------------------------------------
>
> This software is free for private usage. It was created for HAM radio community members. Commercial exploitation is allowed only with permission of authors.
>
> ---------------------------------------------------------
>
> include
> Include
>
> ;------------------------------------------------- -------------------------
> Index equ 0Ch; dummy register
> Count equ 0Dh; inkremental register
> Help equ 0Eh; dummy register
>
> LED0 equ 0Fh
> LED1 equ 010h
> LED2 equ 011h
> LED3 equ 012h
> LED4 equ 013h
> LED5 equ 014h
> LED6 equ 015h
> LED7 equ 016h
>
> TimerH equ 017h; high byte of SW counter
>
> LowB equ 018h; low byte of resulted frequency
> MidB equ 019h; middle byte of resulted frequency
> HigB equ 01Ah; high byte of resulted frequency
>
> Temp equ 01Bh; temporary register
> HIndex equ 01Ch; index register
> LEDIndex equ 01Dh; LED pointer
>
> ;------------------------------------------------- -------------------------
> Include ; timing loop values
>
> ;------------------------------------------------- -------------------------
> Org 0
>
> Start clrf Index
> clrf LEDIndex
>
> clrf LED0
> clrf LED1
> clrf LED2
> clrf LED3
> clrf LED4
> clrf LED5
> clrf LED6
> clrf LED7
>
> clrf LowB
> clrf MidB
> clrf HigB
>
> bsf STATUS, RP0
>
> MOVlw b'00010000'; RA0..RA3 outputs
> MOVwf TRISA; RA4 input
>
> MOVlw b'00000000'; RB0..RB7 outputs
> MOVwf TRISB
>
> Crrwdt;
> MOVlw b'00100111'; Prescaler -> TMR0,
> MOVwf OPTION_REG; 1:256, rising edge
>
> bcf STATUS, RP0;
>
> goto Go;line370
>
> ;+------------------------------------------------ -------------------------+
> ;|The block of subroutines and constants tables|
> ;+------------------------------------------------ -------------------------+
>
> ;+------------------------------------------------ -------------------------+
> ;|3 byte subtraction of the constant from the table, it sets carry|
> ;|if result is negative|
> ;+------------------------------------------------ -------------------------+
>
> Subc24 clrf Temp; it will temporarily save CF
> MOVf Index, W; pointer to low byte of constant
> MOVwf HIndex; W -> HIndex
> call DecTable; W returned with low byte of constant
> bsf STATUS, C; set CF
> subwf LowB, F; LowB - W -> LowB
> ; if underflow -> C = 0
> btfsc STATUS, C
> goto Step1
> bsf STATUS, C
> MOVlw 1
> subwf MidB, F; decrement MidB
> ; if underflow -> C = 0
> btfsc STATUS, C
> goto Step1
>
> bsf STATUS, C
> MOVlw 1
> subwf HigB, F; decrement HigB
> btfsc STATUS, C;if underflow -> C = 0
> goto Step1
> bsf Temp, C; set C
>
> Step1 decf HIndex, F
> MOVf HIndex, W; pointer to middle byte of const
> call DecTable
> bsf STATUS, C
> subwf MidB, F; MidB - W -> MidB
> btfsc STATUS, C;if underflow -> C = 0
> goto Step2
> bsf STATUS, C
> MOVlw 1
> subwf HigB, 1; decrement HigB
> btfsc STATUS, C;if underflow -> C = 0
> goto Step2
> bsf Temp, C; set C
>
> Step2 decf HIndex, F
> MOVf HIndex, W; pointer to middle byte of constatnt
> call DecTable
> bsf STATUS, C
> subwf HigB, F; HigB - W -> HigB
> btfsc STATUS, C;if underflow -> C = 0
> goto ClearCF
> bsf STATUS, C
> goto SubEnd
> ClearCF rrf Temp, C; C -> STATUS
> SubEnd retlw 0
>
> ;+------------------------------------------------ -------------------------+
> ;|3 byte addition of the constant from the table, it sets carry if|
> ;|result overflows|
> ;+------------------------------------------------ -------------------------+
>
> Addc24 clrf Temp; register for temporary storage of CF
> MOVf Index, W; pointer to lower byte of const into W
> MOVwf HIndex; save it into HIndex
> call DecTable; W contains low byte of const
> bcf STATUS, C; clear C
> addwf LowB, 1; W + LowB -> LowB
> btfss STATUS, C; test overflow
> goto Add2
> bcf STATUS, C; clear C
> MOVlw 1
> addwf MidB, F; increment MidB
> btfss STATUS, C
> goto Add2
> bcf STATUS, C; clear C
> MOVlw 1
> addwf HigB, F; increment HigB
> btfss STATUS, C; test overflow
> goto Add2
> bsf Temp, C; store C
>
> Add2 decf HIndex, F; pointer to middle byte into W
> MOVf HIndex, W
> call DecTable
> bcf STATUS, C
> addwf MidB, 1; W + MidB -> MidB
> btfss STATUS, C
> goto Add3
> bcf STATUS, C; clear C
> MOVlw 1
> addwf HigB, 1; increment HigB
> btfss STATUS, C
> goto Add3
> bsf Temp, C
>
> Add3 decf HIndex, F; pointer to higher byte into W
> MOVf HIndex, W
> call DecTable
> bsf STATUS, C
> addwf HigB, F; W + HigB -> HigB,
> btfss STATUS, C
> goto ClarCF
> bsf STATUS, C
> goto AddEnd
> ClarCF rrf Temp, C; C -> STATUS
>
> AddEnd retlw 0
>
> ;+------------------------------------------------ ------------------------+
> ;|Tables of 3-byte constants|
> ;+------------------------------------------------ ------------------------+
> ;|Table of decades|
> ;+------------------------------------------------ ------------------------+
>
> DecTable addwf PCL, F; W + PCL -> PCL
> Retlw 0; 10
> Retlw 0;
> Retlw 0Ah;
>
> Retlw 0; 100
> Retlw 0;
> Retlw 064h;
>
> Retlw 0; 1000
> Retlw 03h;
> Retlw 0E8h;
>
> Retlw 0; 10000
> Retlw 027h;
> Retlw 010h;
>
> Retlw 01h; 100000
> Retlw 086h;
> Retlw 0A0h;
>
> Retlw 0Fh; 1000000
> Retlw 042h;
> Retlw 040h;
>
> ;+------------------------------------------------ -----------------------+
> ;|Table for conversion BCD -> 7 segments|
> ;+------------------------------------------------ -----------------------+
>
> LEDTable addwf PCL, F; W + PCL -> PCL
> Retlwb '00111111'; ..FEDCBA='0'
> Retlwb '00000110'; .....CB.='1'
> Retlwb '01011011'; .G.ED.BA='2'
> Retlwb '01001111'; .G..DCBA='3'
> Retlwb '01100110'; .GF..CB.='4'
> Retlwb '01101101'; .GF.DC.A='5'
> Retlwb '01111101'; .GFEDC.A='6'
> Retlwb '00000111'; .....CBA='7'
> Retlwb '01111111'; .GFEDCBA='8'
> Retlwb '01100111'; .GF..CBA='9'
> Retlwb '10000000'; H.......='.'
>
> ;It follows COMMON ANODE data table
>
> ;LEDTable addwf PCL, F; W + PCL -> PCL
> ;retlwb '11000000'; ..FEDCBA='0'
> ;retlwb '11111001'; .....CB.='1'
> ;retlwb '10100100'; .G.ED.BA='2'
> ;retlwb '10110000'; .G..DCBA='3'
> ;retlwb '10011001'; .GF..CB.='4'
> ;retlwb '10010010'; .GF.DC.A='5'
> ;retlwb '10000010'; .GFEDC.A='6'
> ;retlwb '11111000'; .....CBA='7'
> ;retlwb '10000000'; .GFEDCBA='8'
> ;retlwb '10011000'; .GF..CBA='9'
> ;retlwb '01111111'; H.......='.'
>
> ;+------------------------------------------------ ------------------------+
> ;|The main cycle entry point|
> ;+------------------------------------------------ ------------------------+
> ;|Routine for conversion of 3-byte number into 7 digits|
> ;+------------------------------------------------ ------------------------+
>
> Go bsf STATUS, RP0
> MOVlw b'00000000'
> MOVwf TRISB
> bcf STATUS, RP0
>
> MOVlw 6*3-1; pointer to dec.table
> MOVwf Index; 6*3-1 -> Index
>
> MOVlw 9; maximum of subtractions
> MOVwf Count; 9 -> Count
>
> clrf Help
>
> MOVlw 6
> MOVwf LEDIndex
>
> Divide call Subc24; subtract until result is negative,
> btfsc STATUS, C; add last subtracted number
> goto Add24; next digit
> incf Help, F
> decf Count, F
> btfss STATUS, Z
> goto Divide
> MOVlw 3
> subwf Index, F
> goto Next
>
> Add24 call Addc24
> MOVlw 3
> subwf Index, F
>
> Next MOVlw 9
> MOVwf Count
> MOVlw LED1; LED1 -> W
> addwf LEDIndex, W; LED1 + LEDIndex -> W
> MOVwf Temp
> decf Temp, F; LEDIndex + LED1 -1 -> TEMP
> MOVf Temp, W
>
> MOVwf FSR; W -> FSR
> MOVf Help, W; Help -> W
> clrf Help; save result at LEDx
> MOVwf INDF; W -> LED(6..1)
> decf LEDIndex, F
>
> MOVlw 1
> addwf Index, W
> btfss STATUS, Z
> goto Divide
>
> MOVf LowB, W
> MOVwf LED0; the rest -> LED0
>
> ;+------------------------------------------------ -----------------------+
> ;|Registers LED0..LED6 are filled with values|
> ;+------------------------------------------------ -----------------------+
>
> clrf TimerH
>
> clrf TMR0
> Nop
> Nop
>
> clrf LEDIndex
>
> MOVlw .60; set initial counter value
> MOVwf Index; 60 -> Index
>
> clrf INTCON; global INT disable, TMR0 INT disable
> ; clear TMR0 overflow bite
>
> ;+------------------------------------------------ ---------------------+
> ;|Start of the measurement: RA3 + RA4 set input|
> ;+------------------------------------------------ ---------------------+
>
> MOVlw b'00010000'; all ports set L, RA4 set H
> MOVwf PORTA
>
> bsf STATUS, RP0
> MOVlw b '00011000'; RA0..RA2 output, RA3, RA4 input
> MOVwf TRISA
> bcf STATUS, RP0
>
> ;+------------------------------------------------ -----------------------+
> ;|7-step cycle of digits|
> ;+------------------------------------------------ -----------------------+
>
> LEDCycle MOVlw LED0
> addwf LEDIndex, W; LED1 + LEDIndex -> W
>
> MOVwf FSR; W -> FSR
> MOVf INDF, W; LED(0..6) -> W
> call LEDTable; W contains segments
>
> MOVwf Temp; test for decimal point
> MOVlw 5
>
> bsf STATUS, Z
> subwf LEDIndex, W
> btfss STATUS, Z
> goto NoDot
> bsf Temp, 7; common cathode....
> ;bcf Temp, 7; common anode....
>
> NoDot MOVf Temp, W
> MOVwf PORTB; segments -> PORTB
>
> MOVf LEDIndex, W; LEDIndex -> W
> Nop
> MOVwf PORTA; digit number -> PORTA
>
> ;+------------------------------------------------ ------------------------
> ;Test for TMR0 overflow
> ;+------------------------------------------------ ------------------------
>
> btfss INTCON, 2; Test for TMR0 overflow
> goto DoNothing
> incf TimerH, F; YES! Increment SW counter
> bcf INTCON, 2; clear overflow bite
> goto O_K
>
> DoNothing nop
> Nop
> Nop
>
> ;+------------------------------------------------ -----------------------+
> ;|The first timing loop 2 + 3*T1 processor cycles|
> ;+------------------------------------------------ -----------------------+
>
> O_K MOVlw T1
> MOVwf Temp
>
> Pause decfsz Temp, F
> goto Pause
> Nop
>
> ;+------------------------------------------------ -----------------------+
> ;|The end of one digit processing|
> ;+------------------------------------------------ -----------------------+
>
> incf LEDIndex, F
> MOVlw 7; is 7th?
> bcf STATUS, Z
> subwf LEDIndex, W
> btfss STATUS, Z
> goto LEDCycle; next digit
> Nop
>
> ;+------------------------------------------------ -----------------------+
> ;|The second timing loop 2 + 3*T2 processor cycles|
> ;+------------------------------------------------ -----------------------+
>
> MOVlw T2
> MOVwf Temp
>
> Again decfsz Temp, F
> goto Again
> Nop
>
> ;+------------------------------------------------ -----------------------+
> ;|The end of one 7-digits processing|
> ;+------------------------------------------------ -----------------------+
>
> clrf LEDIndex
> decfsz Index, F
> goto LEDCycle; next 7*LED
> Nop
>
> ;+------------------------------------------------ -----------------------+
> ;|The third timing loop 2 + 9*T3 + Z processor cycles|
> ;+------------------------------------------------ -----------------------+
>
> MOVlw T3
> MOVwf Temp
>
> EndPause decfsz Temp, F
> goto EndPause
> Nop
>
> Include
> ;nop;Z times NOP
> ;nop;60*(6+7*(36+3*T1)+3*T2)+2+3*T3+Z
>
> ;=========== Last test TMR0 overflow bit ============
> btfss INTCON, 2; 1
> goto Nothing2Do;3
> incf TimerH, F;3
> bcf INTCON, 2; 4
> goto Nx;6
>
> Nothing2Do nop;4
> Nop;5
> Nop;660*(6+7*(36+3*T1)+3*T2)+8+3*T3+Z
>
> ;=========== Stop measurement: RA3 out; RA4 in =================
> Nx clrw; For common cathode
> ;Nx MOVlw b'11111111'; For common anode
>
> MOVwf PORTB
> MOVlw b'00010000'; RA0..RA3 = 0
> MOVwf PORTA; W -> PORTA
>
> bsf STATUS, RP0
> MOVlw b'00010000'; RA0..RA3 output
> MOVwf TRISA; RA4 input
> bcf STATUS, RP0
>
> btfsc INTCON, 2; really final check
> incf TimerH, F
> bcf INTCON, 2
>
> ;========== Clear storage count value ==========|
> MOVf TMR0, W
> MOVwf MidB; TMR0 -> MidB
> MOVf TimerH, W
> MOVwf HigB; TimerH -> HigB
> clrf Temp
> CountIt incf Temp, F
> bsf PORTA, 3; pseudo signal
> bcf PORTA,3;
> ;
> bcf INTCON, 2
> MOVf TMR0, W; TMR0 -> W
> bcf STATUS, Z
> subwf MidB, W
> btfsc STATUS, Z
> goto CountIt
> incf Temp, F
> comf Temp, F
> incf Temp, F
> incf Temp, W
>
> MOVwf LowB
> ;===========================
> goto Go
>
> ;===============================
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