;----------------------------------------------------------------------; ; TMR04M.ASM Show TMR0 in decimal on LCD after counting 1 second ; ;----------------------------------------------------------------------; ; 555 V+ PIC16F84 ; .----------. | .-----------. ; gnd ---|gnd Vcc|--- V+ [R] -|RA2 RA1|----[LCD E] ; .-|trig dis|----------| -|RA3 RA0|----[LCD RS] ; RA4<--|-|out thres|--.--{r}--' in>-|RA4 OSC1|--|X|__ gnd ; V+ --|-|rst cont| |--|<---' V+--|MCLR OSC2|--|X| X = 4 MHz ; | '----------' | gnd--|Vss Vdd|--- V+ cer. res. ; '---------------' [LCD D4]----|RB0 RB7|- ; | C [LCD D5]----|RB1 RB6|- V+ = 4.5 or 5V ; '---||---gnd [LCD D6]----|RB2 RB5|---[PB]--- gnd ; C = 0.001-0.1 mfd [LCD D7]----|RB3 RB4|---[PB]--- gnd ; -{r}- = 33K '-----------' ; -|<- = 1n4148 [R] = 10K variable resistor -[PB]- = pushbutton ; LCD pin connections: ; 1 - gnd ground 2 - Vcc V+ 3 - cont. 10K pot V+ & gnd ; 4 - RS RA0 PIC(17) 5 - RW gnd 6 - E RA1 PIC(18) ; 7 - D0 gnd 8 - D1 gnd 9 - D2 gnd 10 - D3 gnd ; 11 - D4 RB0 (6) 12 - D5 RB1 (7) 13 - D6 RB2 (8) 14 - D7 (9) LIST P=16F84 ; 16F84 Runs at 4 MHz INCLUDE "p16f84.inc" __CONFIG _PWRTE_ON & _XT_OSC & _WDT_OFF ERRORLEVEL -224 ; supress annoying message from tris ERRORLEVEL -302 ; supress message fromf page change ; Define Information #DEFINE RS PORTA, 0 ; RA0 is RS line of LCD #DEFINE E PORTA, 1 ; RA1 is E line of LCD ; RB0-RB3 are D4-D7 of LCD #DEFINE upbutton PORTB, 4 ; RB4 is the up button #DEFINE dnbutton PORTB, 5 ; RB5 is the down button ; Macro EStrobe MACRO ; Strobe the "E" Bit bsf E bcf E ENDM CBLOCK 0CH Temp ; a temporary variable count ; counter precount ; holds value for prescalar bin ; binary number to be converted to BCD hundreds ; BCD hundreds result tens_and_ones ; BCD tens and ones result cntmsec ; used in counting milliseconds ENDC ORG 0 ; start at location 0 goto main ; jump over to main routine ;----------------------------------------------------------------------; ; Data for message to be output ; ;----------------------------------------------------------------------; shomsg: ; Message to Output addwf PCL, f ; Output the Characters m0 dt "TMR0 Value:", 0 m1 dt "Multiply by:", 0 ;----------------------------------------------------------------------; ; Ratios of Prescaler ; ;----------------------------------------------------------------------; preratio: addwf PCL, f ; select offset using W dt D'2',D'4',D'8',D'16',D'32',D'64',D'128' ;----------------------------------------------------------------------; ; Initialize the ports ; ;----------------------------------------------------------------------; Init: clrf PORTA clrf PORTB movlw B'00010000' ; RA4 input, others outputs tris PORTA movlw B'00110000' ; RB4, RB5 input, others outputs tris PORTB movlw B'00100001' ; pull-ups enabled ; prescaler assigned to RA4 ; prescaler set to 1:4 option clrf precount return ;----------------------------------------------------------------------; ; Initialize the LCD ; ;----------------------------------------------------------------------; initlcd: movlw D'40' call nmsec ; Wait 40 msecs before Reset bcf RS ; send an 8 bit instruction movlw 0x03 ; Reset Command call NybbleOut ; Send the Nybble call Dlay5 ; Wait 5 msecs before Sending Again EStrobe call Dlay160 ; Wait 160 usecs before Sending 2nd Time EStrobe call Dlay160 ; Wait 160 usecs before Sending 3rd Time bcf RS ; send an 8 bit instruction movlw 0x02 ; Set 4 Bit Mode call NybbleOut call Dlay160 movlw 0x028 ; 4 bit, 2 Line, 5x7 font call SendINS movlw 0x010 ; display shift off call SendINS movlw 0x001 ; Clear the Display RAM call SendINS call Dlay5 ; Note, Can take up to 4.1 msecs movlw 0x006 ; increment cursor call SendINS movlw 0x00C ; display on cursor off call SendINS return ;----------------------------------------------------------------------; ; Send the character in W out to the LCD ; ;----------------------------------------------------------------------; SendASCII addlw '0' ; Send nbr as ASCII character SendCHAR ; Send the Character to the LCD movwf Temp ; Save the Temporary Value swapf Temp, w ; Send the High Nybble bsf RS ; RS = 1 call NybbleOut movf Temp, w ; Send the Low Nybble bsf RS call NybbleOut return ;----------------------------------------------------------------------; ; Send an instruction in W out to the LCD ; ;----------------------------------------------------------------------; SendINS ; Send the Instruction to the LCD movwf Temp ; Save the Temporary Value swapf Temp, w ; Send the High Nybble bcf RS ; RS = 0 call NybbleOut movf Temp, w ; Send the Low Nybble bcf RS call NybbleOut return ;----------------------------------------------------------------------; ; Send the nibble in W out to the LCD ; ;----------------------------------------------------------------------; NybbleOut ; Send a Nybble to the LCD movwf PORTB EStrobe ; Strobe out the LCD Data call Dlay160 ; delay for 160 msec return ;----------------------------------------------------------------------; ; Output the message on the LCD ; ;----------------------------------------------------------------------; OutMessage: movwf FSR ; Point at first letter OutLoop: movf FSR, w ; Get pointer into W incf FSR, f ; Set up for next letter call shomsg ; Get character to output iorlw 0 ; At the End of the Message? btfsc STATUS, Z ; Skip if not at end return ; Yes - Equal to Zero call SendCHAR ; Output the ASCII Character goto OutLoop ; Get the next character ;----------------------------------------------------------------------; ; Change binary nbr in bin to BCD ; ;----------------------------------------------------------------------; binary_to_bcd ; by Scott Dattalo clrf hundreds ; found at http://www.piclist.com swapf bin, W addwf bin, W andlw B'00001111' skpndc addlw 0x16 skpndc addlw 0x06 addlw 0x06 skpdc addlw -0x06 btfsc bin,4 addlw 0x16 - 1 + 0x6 skpdc addlw -0x06 btfsc bin,5 addlw 0x30 btfsc bin, 6 addlw 0x60 btfsc bin,7 addlw 0x20 addlw 0x60 rlf hundreds, f btfss hundreds, 0 addlw -0x60 movwf tens_and_ones btfsc bin,7 incf hundreds, f return ;----------------------------------------------------------------------; ; time delay routines ; ;----------------------------------------------------------------------; Dlay160 movlw D'40' ; 160 usec delay entry point micro4 addlw H'FF' ; subtract 1 from 'W' btfss STATUS,Z ; skip when you reach zero goto micro4 ; more loops return Dlay5: movlw D'5' ; 5 msec delay entry point goto nmsec msec250: ; a subroutine to delay 250 msec movlw D'250' ;*** N millisecond delay routine *** nmsec: movwf cntmsec ; delay for N (in W) millisec msecloop: movlw D'248' ; 1 usec for load call micro4 ; this instruction is 995 usec nop ; 1 usec decfsz cntmsec,f ; 1 usec, (2 if skip taken) goto msecloop ; 2 usec here 995+5 = 1 msec return ;----------------------------------------------------------------------; ; Display binary value in W in decimal ; ; ;----------------------------------------------------------------------; DispDec movwf bin call binary_to_bcd movf hundreds, W call SendASCII swapf tens_and_ones, W andlw H'F' call SendASCII movf tens_and_ones, W andlw H'F' call SendASCII return ;----------------------------------------------------------------------; ; Return the prescalar ratio setting in W ; ;----------------------------------------------------------------------; getpre: bsf STATUS, RP0 ; change to page 1 movf OPTION_REG, W ; get OPTION register bcf STATUS, RP0 ; back to page 0 andlw 7 ; get 1st 3 bits in W return ;----------------------------------------------------------------------; ; Check pushbuttons and increment or decrement prescalar ; ;----------------------------------------------------------------------; ckbuttons: call getpre ; get prescalar ratio # in Temp movwf Temp btfss upbutton ; Skip if up button not pressed goto preup ; increment prescalar btfss dnbutton ; Skip if down button not pressed goto predown ; decrement prescalar return ; no buttons pressed, return preup: incf Temp, f ; up one btfsc Temp, 3 ; if reach 8, go back to zero clrf Temp goto newpre ; and fix new ratio predown: decf Temp, f ; down one movlw H'FF' ; check for underflow subwf Temp, W btfss STATUS, Z ; skip if underflow goto newpre ; and fix new ratio movlw 7 ; reset to 7 movwf Temp newpre: bsf STATUS, RP0 ; change to page 1 movlw B'11111000' ; mask out low three bits andwf OPTION_REG, W ; result in W bcf STATUS, RP0 ; back to page 0 iorwf Temp, W ; add in new prescalar ratio # option ; update OPTION return ; no debounce necessary because it ; will be one second till you get ; baclk to this routine, even if the ; button is still pressed. ;----------------------------------------------------------------------; ; The Main routine ; ;----------------------------------------------------------------------; main: call Init ; initialize ports, set up timer call initlcd ; initialize the LCD movlw H'80' ; position at 1st line column 0 call SendINS movlw m0 -2 ; send 'TMR0 Value:' message call OutMessage movlw H'C0' call SendINS ; position at 2nd line column 0 movlw m1 -2 ; send 'Multiply by:' message call OutMessage sholoop: call ckbuttons ; update prescalar if buttons pushed movlw H'CD' ; position at 2nd line column 13 call SendINS call getpre ; get prescalar ratio # in binary call preratio ; change to prescalar ratio call DispDec ; put it on LCD movlw H'8C' ; position at 1st line column 12 call SendINS bcf INTCON, T0IF ; clear timer zero interrupt flag clrf TMR0 ; zero TMR0 call msec250 ; wait a total of one second call msec250 call msec250 call msec250 movf TMR0, W ; retrieve timer zero btfsc INTCON, T0IF ; check if timer overflowed goto overload ; yes, display 'OVR' call DispDec ; display TMR0 value goto sholoop ; repeat forever overload movlw 'O' ; output 'OVR' call SendCHAR movlw 'V' call SendCHAR movlw 'R' call SendCHAR goto sholoop ; and continue end
file: /Techref/piclist/cheapic/tmr04m.asm, 14KB, , updated: 2000/12/7 16:35, local time: 2024/10/13 18:32,
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