please dont rip this site

Piclist Cheapic TMR04M.ASM

;----------------------------------------------------------------------;
; 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: 2024/10/31 16:39,
TOP NEW HELP FIND: 
52.14.234.213:LOG IN
©2024 PLEASE DON'T RIP! THIS SITE CLOSES OCT 28, 2024 SO LONG AND THANKS FOR ALL THE FISH!

 ©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?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://sxlist.com/techref/piclist/cheapic/tmr04m.asm"> piclist cheapic tmr04m</A>

Did you find what you needed?

 

Welcome to sxlist.com!


Site supported by
sales, advertizing,
& kind contributors
just like you!

Please don't rip/copy
(here's why

Copies of the site on CD
are available at minimal cost.
 

Welcome to sxlist.com!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .