;----------------------------------------------------------------------; ; SWCNT4M.ASM Counts presses of a pushbutton on RB4, 4 MHz oscillator ; ;----------------------------------------------------------------------; ; .-----------. ; -|RA2 RA1|- V+ = 4.5 or 5 Volts ; -|RA3 RA0|- X = 4 MHz cer. res. ; -|RA4 OSC1|--|X|___ gnd ; -{r}- = 470 ohm V+ ---|MCLR OSC2|--|X| ; -|<- = LED gnd ---|Vss Vdd|--- V+ ; gnd ---|<--{r}--|RB0 RB7|- ; gnd ---|<--{r}--|RB1 RB6|- ; gnd ---|<--{r}--|RB2 RB5|- ; gnd ---|<--{r}--|RB3 RB4|---[PB]--- gnd ; '-----------' ; PIC16F84 -[PB]- pushbutton LIST P=16F84 ; tells which processor is used INCLUDE "p16f84.inc" ; defines various registers etc. Look ERRORLEVEL -224 ; supress annoying message from tris __CONFIG _PWRTE_ON & _XT_OSC & _WDT_OFF ; config. switches #DEFINE pushbutton PORTB, 4 ; RB4 is pushbutton to ground ;----------------------------------------------------------------------; ; Here we set up our own registers start at the 1st free address ; ;----------------------------------------------------------------------; CBLOCK H'0C' cntmsec ; counter used in millisecond delays ENDC ORG 0 ; start a program memory location zero ;----------------------------------------------------------------------; ; First we set up all bits of PORT A and B as outputs ; ;----------------------------------------------------------------------; movlw B'00000000' ; all bits outputs tris PORTA ; on PORT A movlw B'00010000' ; RB4 input, all others outputs tris PORTB ; and PORT B movlw 0 ; set bit 7 of OPTION = 0 .... option ; port B pullups activated ;----------------------------------------------------------------------; ; This is the main program ; ;----------------------------------------------------------------------; clrf PORTB ; start with zero, ( all LEDs off ) loop: btfsc pushbutton ; switch closed, (gives 0)? goto loop ; not yet, continue to wait ; switch has been detected closed incf PORTB, f ; add 1 to port B ; wait a while to make sure switch has ; settled (debounce closure) movlw D'10' ; wait about 10 msec call nmsec ; may be bounce on closure ; now wait for release btfss pushbutton ; will be high (1) when released goto $ -1 ; still low ; must wait, make sure bouncing stopped movlw D'10' ; 10 milliseconds call nmsec ; release bounce less, but still there ; and check again btfss pushbutton ; if set, still released goto $ -5 ; still low start release wait all over goto loop ; loop forever ;----------------------------------------------------------------------; ; time delay routines ; ;----------------------------------------------------------------------; micro4 addlw H'FF' ; subtract 1 from 'W' btfss STATUS,Z ; skip when you reach zero goto micro4 ; more loops return ;*** 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, loop = 995+5 = 1 msec return end ; end of program
file: /Techref/piclist/cheapic/swcnt4m.asm, 4KB, , updated: 2000/12/8 12:45, local time: 2024/8/14 22:24,
3.133.111.29:LOG IN
|
©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://ecomorder.com/techref/piclist/cheapic/swcnt4m.asm"> piclist cheapic swcnt4m</A> |
Did you find what you needed? |
Welcome to ecomorder.com! |
Welcome to ecomorder.com! |
.