;**************************************************************************** ; ; LCD Tachometer ; ;**************************************************************************** ; Bruce Abbott bhabbott@paradise.net.nz ; ; Hold button on RA0 (pin 17) ; Blade Select button on RA1 (pin 18) ; Opto sensor input on RB0 (pin 7) ; processor PIC16f628 include P16f628.inc radix dec errorlevel -302,-305 #DEFINE FALSE 0 #DEFINE TRUE 1 #DEFINE CLKFRQ 4000 ; CPU clock frequency in KHz ; Port A bit assignments #DEFINE BLADE_BTN 1 ; pin 18, blade select button #DEFINE HOLD_BTN 0 ; pin 17, hold button ; Port B bit assignments ; RB7 = pin 13, LCD D7 ; 6 = pin 12, LCD D6 ; 5 = pin 11, LCD D5 ; 4 = pin 10, LCD D4 ; 3 = pin 9, LCD E ; 2 = pin 8, LCD RS ; 1 = pin 7, n/c #DEFINE PULSE_IN 0 ; RB0 (pin 6) = opto sensor input #DEFINE LCD2LINE FALSE ; true if LCD display has two logical lines __config _BODEN_ON&_WDT_OFF&_LVP_OFF&_PWRTE_ON&_HS_OSC ;============================================================================ ; Macro to create offsets for file registers in RAM ; ByteAddr SET 32 ; user file registers start here BYTE MACRO ByteName ByteName EQU ByteAddr ByteAddr SET ByteAddr+1 ENDM ;============================================================================ ; number of propellor blades BYTE Choice ; decimal digits BYTE Digit_0 ; units BYTE Digit_1 ; tens BYTE Digit_2 ; hundreds BYTE Digit_3 ; thousands BYTE Digit_4 ; ten thousands ; LCD variables BYTE ADRESS BYTE ADRESS2 BYTE CHAR BYTE CHAR2 BYTE dx_temp1 BYTE dx_temp2 BYTE dx_temp3 BYTE LCDtemp ; message pointer BYTE msg_ptr ; period to rpm converison constant (rpm = constant/period) BYTE const_0 BYTE const_1 BYTE const_2 ; rpm BYTE rpm ; 1 digit of decimal rpm ; remainder BYTE remain_0 BYTE remain_1 BYTE remain_2 ; period (measured using timer0) BYTE period_0 BYTE period_1 BYTE period_2 ; misc variables BYTE temp BYTE dflags BYTE pulse_count ; reset vector ;////////////////////////////////////////////////////////////////////// ORG 0 goto MAIN ; interrupt vector ;////////////////////////////////////////////////////////////////////// ORG 4 cblock 0x70 ; allocate variables in RAM WorkSave ; that is common to all banks! StatSave endc interrupt: movwf WorkSave movf STATUS,w ; save working registers movwf StatSave bcf STATUS,RP0 ; register bank 0 check_int: btfss INTCON,T0IF ; timer0 overflowed ? goto RB0_int ; if not, must be RB0 change int TMR0_int: ; timer0 overflow incfsz period_1 ; count number of overflows goto tmr0_done incf period_2 movf period_2,W sublw 4 ; total > 196607 ? skpc goto low_rpm tmr0_done: bcf INTCON,T0IF ; clear timer int btfss INTCON,INTF ; input pulse detected? goto Int_Done nop nop nop nop nop nop RB0_int: incfsz pulse_count,F ; first pulse ? goto next_pulse first_pulse: clrf TMR0 ; reset timer clrf period_1 clrf period_2 bcf INTCON,T0IF ; clear timer0 int RB0_done: bcf INTCON,INTF ; clear RB0 int flag Int_Done: movf StatSave,w movwf STATUS swapf WorkSave ; restore working registers swapf WorkSave,w RETFIE next_pulse: movlw 10 ; integrate pulses subwf pulse_count,W skpz ; all pulses received ? goto RB0_done got_all_pulses: bsf STATUS,RP0 ; bank 1 bsf OPTION_REG,T0CS ; stop timer0 bcf STATUS,RP0 ; bank 0 btfss INTCON,T0IF ; timer0 overflowed ? goto get_time incfsz period_1,F ; count number of overflows goto get_time incf period_2,F movf period_2,W sublw 4 ; total > 196607 ? skpc goto low_rpm get_time: movf TMR0,W ; get timer0 movwf period_0 goto Calc_RPM ; calculate and display RPM low_rpm: ; timed out goto start ;////////////////////////////////////////////////////////////////////// ;*---------------------------- user code -----------------------------* message: addwf PCL,F msg: RETLW 'L' RETLW 'C' RETLW 'D' RETLW ' ' RETLW 'T' RETLW 'A' RETLW 'C' RETLW 'H' RETLW 0 ver_: RETLW 'V' RETLW 'E' RETLW 'R' RETLW ' ' RETLW '0' RETLW '.' RETLW '1' RETLW '2' RETLW 0 ; blades messages two_: RETLW '2' RETLW 0 three_: RETLW '3' RETLW 0 four_: RETLW '4' RETLW 0 five_: RETLW '5' RETLW 0 six_: RETLW '6' RETLW 0 ;----------------------------------------------- ; Set constant (k) for prop blades ; ; rpm = k/period ; set_prop: clrf PCLATH movf Choice,W addwf PCL goto seq_TWO ; 2 blades goto seq_THREE ; 3 blades goto seq_FOUR ; 4 blades goto seq_FIVE ; 5 blades goto seq_SIX ; 6 blades return seq_TWO movlw 0 movwf const_2 movlw high 15000 movwf const_1 movlw low 15000 movwf const_0 return seq_THREE movlw 0 movwf const_2 movlw high 10000 movwf const_1 movlw low 10000 movwf const_0 return seq_FOUR movlw 0 movwf const_2 movlw high 7500 movwf const_1 movlw low 7500 movwf const_0 return seq_FIVE movlw 0 movwf const_2 movlw high 6000 movwf const_1 movlw low 6000 movwf const_0 return seq_SIX movlw 0 movwf const_2 movlw high 5000 movwf const_1 movlw low 5000 movwf const_0 return #include lcd_v_a1.asm ;------------------------------------------- ; Display Sign-on Message on LCD ; display_signon movlw 0 call ddram_adress movlw msg-msg goto display_message ;------------------------------------------- ; Display Software Version on LCD ; display_sw_version movlw 0 call ddram_adress movlw ver_-msg goto display_message ;------------------------------------------- ; Display Number of Blades on LCD ; display_prop: movlw 0 call ddram_adress movf Choice,W ADDWF PCL,F ; 2-6 blades goto display_TWO goto display_THREE goto display_FOUR goto display_FIVE goto display_SIX return display_TWO movlw two_-msg goto display_message display_THREE movlw three_-msg goto display_message display_FOUR movlw four_-msg goto display_message display_FIVE movlw five_-msg goto display_message display_SIX movlw six_-msg goto display_message ;--------------------------------------------------------- ; Display 5 digits of RPM on LCD ; ; - leading zeros blanked ; - ',' separator between thousands and hundreds ; - last digit forced to '0' if > 9,999 rpm ; ; " 99,990" ; " 9,999" ; " 999" ; " 99" ; " 9" ; display_rpm clrf dflags ; assume all digits zero movlw B'00001111' andwf Digit_4 skpz ; ten thousands > zero ? bsf dflags,4 andwf Digit_3 skpz ; thousands > zero ? bsf dflags,3 andwf Digit_2 skpz ; hundreds > zero ? bsf dflags,2 andwf Digit_1 skpz ; tens > zero ? bsf dflags,1 movlw 1 ; set cursor position call ddram_adress movlw B'00110000' ; ASCII mask iorwf Digit_0 iorwf Digit_1 iorwf Digit_2 ; 0 to 9 -> "0" to "9" iorwf Digit_3 iorwf Digit_4 movlw ' ' call prt_char ; show ' ' movf Digit_4,w btfsc dflags,4 ; ten thou = 0 ? bsf dflags,0 ; leading zeros off btfss dflags,0 ; ' ' if leading zero movlw ' ' call prt_char ; show ten thousands or ' ' movf Digit_3,w btfsc dflags,3 bsf dflags,0 btfss dflags,0 movlw ' ' call prt_char ; show thousands or ' ' movlw ',' btfss dflags,0 movlw ' ' call prt_char ; show ',' or ' ' movf Digit_2,w btfsc dflags,2 bsf dflags,0 btfss dflags,0 movlw ' ' call prt_char ; show hundreds or ' ' movf Digit_1,w btfsc dflags,1 bsf dflags,0 btfss dflags,0 movlw ' ' call prt_char ; show tens or ' ' movf Digit_0,w btfsc dflags,4 ; units = '0' if rpm > 9,999 movlw '0' call prt_char ; show units or '0' RETURN ;--------------------------------------------------------- ; Display Text Message on LCD ; display_message movwf msg_ptr call message ; get next char in message andlw 0xFF ; end of message ? skpnz RETURN call prt_char ; show character movf msg_ptr,W addlw 1 ; next character goto display_message ;-------------------------------------------------------------- ; Convert period to rpm (1 decimal digit) ; ; W = const / period ; ; IN: const = blades constant eg. 15000 (1st digit), or ; previous remainder * 10 (subsequent digits) ; ; period = measured time between pulses ; ; OUT: W = decimal digit 0~9 ; remain = remaining part of rpm ; divide: clrf temp ; digit = 0 div_1: movf const_0,W movwf remain_0 movf const_1,W movwf remain_1 ; remain = const movf const_2,W movwf remain_2 movf period_0,W subwf const_0 skpnc goto div_2 movlw 1 subwf const_1 ; const = const - period skpc subwf const_2 skpc goto div_3 ; done if negative div_2: movf period_1,W subwf const_1 movlw 1 skpc subwf const_2 skpc ; done if negative goto div_3 movf period_2,w subwf const_2 skpc ; done if negative goto div_3 incf temp ; increment rpm goto div_1 ; next subtract div_3: movf temp,W return ;--------------------------------------------------- ; Multiply times 10 ; ; constant = remainder * 10 ; mult_10: bcf STATUS,C rlf remain_0 ; remainder * 2 rlf remain_1 rlf remain_2 movf remain_0,W movwf const_0 movf remain_1,W ; (remainder * 2) -> constant movwf const_1 movf remain_2,W movwf const_2 bcf STATUS,C rlf remain_0 rlf remain_1 ; remainder * 4 rlf remain_2 bcf STATUS,C rlf remain_0 rlf remain_1 ; remainder * 8 rlf remain_2 movf remain_0,W addwf const_0 skpc goto mul_101 incfsz const_1 ; constant=(remainder*8)+(remainder*2) goto mul_101 incf const_2 mul_101 movf remain_1,W addwf const_1 skpnc incf const_2 movf remain_2,W addwf const_2 return ;--------------------------------------------------------------------- ; Calculate amount of time to wait before refreshing display. ; Ensures constant display update rate, even though measurement ; period varies with rpm. ; refresh_delay: movlw 6 refr_1 bcf STATUS,C rlf period_1 rlf period_2 ; period * 64 addlw -1 skpz goto refr_1 movf period_2,w ; 0~255 = 0~512mS measurement time sublw 0 goto dx2k ; delay for ( 512 - period ) * 2mS ;----------------------------------------------------------------- ; Main Program ; MAIN IFDEF __16F628 movlw B'00000111' movwf CMCON ; disable comparator ENDIF clrf PORTA clrf PORTB movlw B'00001111' ; set PortA directions tris PORTA movlw B'00000001' ; set PortB directions tris PORTB ; no weak pullups, RB0 int rising edge, TMR0 on RA4, prescale 1:2 movlw B'11110000' option movlw 120 call dx2k ; wait 0.25 seconds call set_4bit_mode call init_display ; init LCD display call clear_display ; clear LCD display movlw 0 ; choose 2 blades movwf Choice call display_signon ; show signon message movlw 250 ; wait 0.5 second call dx2k call display_sw_version ; show software version movlw 250 call dx2k ; wait 0.5 second start: movlw 0 call ddram_adress ; set cursor call display_prop ; show number of blades clrf Digit_0 clrf Digit_1 clrf Digit_2 ; rpm = 0 clrf Digit_3 clrf Digit_4 call display_rpm ; show rpm mainloop: bsf STATUS,RP0 bsf OPTION_REG,T0CS ; stop timer0 bcf STATUS,RP0 bcf INTCON,GIE ; global interrupt disable bcf INTCON,T0IE ; disable timer int bcf INTCON,INTE ; disable RB0 int movlw -1 movwf pulse_count ; pulse_count = -1 clrf period_0 clrf period_1 ; total time = 0 clrf period_2 clrf TMR0 ; reset timer0 bcf INTCON,T0IF ; clear timer0 int flag bsf INTCON,T0IE ; enable timer0 int bcf INTCON,INTF ; clear RB0 int flag bsf INTCON,GIE ; global interrupt enable bsf STATUS,RP0 bcf OPTION_REG,T0CS ; start timer0 bcf STATUS,RP0 ; Timer is running. If too much time passes without any signal, ; jump directly from Interrupt back to Start. wait_no_pulse: btfsc PORTB,PULSE_IN ; wait until blade passes goto measure btfsc PORTA,BLADE_BTN ; button pressed ? goto wait_no_pulse goto key_press measure: bcf INTCON,INTF ; clear RB0 int flag bsf INTCON,INTE ; enable RB0 int ; ; RB0 Interrupt occurs when next blade passes the sensor. After ; 10 blade passes, jump directly from Interrupt to calc_rpm. ; wait_measure: nop btfsc PORTA,BLADE_BTN ; button pressed ? goto wait_measure key_press: bcf INTCON,GIE bcf INTCON,T0IF ; disable ints bcf INTCON,INTF call clear_display ; clear LCD display incf Choice,F ; next blade choice movlw 5 subwf Choice,W ; 6 blades maximum skpnz clrf Choice call set_prop ; set number of prop blades call clear_display call display_prop ; show number of prop blades key_hold: movlw 50 call dx2k ; debounce 100mS btfss PORTA,BLADE_BTN ; button still pressed ? goto key_hold movlw 50 call dx2k ; debounce 100mS goto start ;------------------------------------------------------------------- ; Calculate decimal RPM digits from period, and Display it on LCD ; ; rpm = constant / period ; Calc_RPM: call set_prop ; get constant call divide ; rpm digit = constant/period movwf Digit_4 ; put Ten Thousands digit call mult_10 ; remainder * 10 call divide ; rpm digit = remainder/period movwf Digit_3 ; store Thousands digit call mult_10 call divide movwf Digit_2 ; put Hundreds digit call mult_10 call divide movwf Digit_1 ; put Tens digit call mult_10 call divide movwf Digit_0 ; put Units digit movlw 0 call ddram_adress ; set cursor position movlw ' ' ; blank out # of blades call prt_char call display_rpm ; show the rpm digits call refresh_delay ; reduce refresh rate hold: btfss PORTA,HOLD_BTN ; hold button pressed ? goto hold ; halt until released! goto mainloop END