This is a conglomerate of many different examples I read on the PIClist
website (there are no 18FXXX examples that I could see so I had to convert
the code, it was a good learning experience) and what I could glean from
the datasheet. All it does is depending on whether I switch RB4 of port B
between VCC and VSS (through 1k resister) it will run the appropriate
routine. I'm looking for constructive criticism. (the timing part is not
accurate, but it delays enough to work). It compiles and runs perfectly.



;-----------------------------------------------------------------------;
; ROT&CNT.ASM   Switch between rotating and counting on LEDs (RD0-RD7)  ;
;-----------------------------------------------------------------------;
         LIST P=PIC18F452
         INCLUDE "p18f452.inc"
         __CONFIG    _CONFIG1H, _OSCS_OFF_1H & _XT_OSC_1H
                 __CONFIG    _CONFIG2L, _BOR_ON_2L & _BORV_20_2L & _PWRT_ON_2L
                 __CONFIG    _CONFIG2H, _WDT_OFF_2H & _WDTPS_128_2H
                 __CONFIG    _CONFIG3H, _CCP2MX_ON_3H
                 __CONFIG    _CONFIG4L, _STVR_ON_4L & _LVP_OFF_4L &
_DEBUG_OFF_4L
                 __CONFIG    _CONFIG5L, _CP0_OFF_5L & _CP1_OFF_5L &
_CP2_OFF_5L & _CP3_OFF_5L
                 __CONFIG    _CONFIG5H, _CPB_OFF_5H & _CPD_OFF_5H
                 __CONFIG    _CONFIG6L, _WRT0_OFF_6L & _WRT1_OFF_6L &
_WRT2_OFF_6L & _WRT3_OFF_6L
                 __CONFIG    _CONFIG6H, _WRTC_OFF_6H & _WRTB_OFF_6H &
_WRTD_OFF_6H
                 __CONFIG    _CONFIG7L, _EBTR0_OFF_7L & _EBTR1_OFF_7L &
_EBTR2_OFF_7L & _EBTR3_OFF_7L
                 __CONFIG    _CONFIG7H, _EBTRB_OFF_7H

                 CBLOCK 0x020
                         CNT1
                         CNT2

                 ENDC

                 goto begin
                 ORG 0x008                       ;interupt vector

                 movlw B'11111111'
                 MOVWF TMR0L             ;load timer0 with 255 so as to get
a 16us delay
                 BCF INTCON, TMR0IF      ;clear timer overflow interupt
flag
                 RETFIE                  ;return from interupt

begin:
                  ORG 0x010              ; start a program memory location zero

                 CLRF PORTD                              ;clear tristate
buffer
                 movlw B'00000000'
                 MOVWF TRISA                     ;set up all bits of PORT A
as outputs
                 MOVWF TRISC                     ;set up all bits of PORT C
as outputs
                 MOVWF TRISD                     ;set up all bits of PORT D
as outputs
                 MOVWF TRISE                     ;set up all bits of PORT E
as outputs
                  movlw B'00010000'       ; RB4 input, all other output (my
switch)
                 MOVWF TRISB
                 movlw B'01000001'
                 MOVWF T0CON                     ;set timer0 as 8 bit,
internal clk, prescale 1:4
                 movlw B'11111111'
                 MOVWF TMR0L                     ;load timer0 with 255 so
as to get a 16us delay
                                                                 ;Delay =
(256 - TMR0 * prescaler)
                                                 ;-----------------------------------------
                                                         ;          Clock
Frequency / 4

                 BSF INTCON, GIE                 ;enable interupts
                 BSF INTCON, TMR0IE              ;enable timer 0 overflow
interupt
                 movlw B'00000001'
                 MOVWF PORTD

;-----------------------------------------------------------------------;
;                      This is the main program                         ;
;-----------------------------------------------------------------------;

loop:
                  btfsc PORTB, RB4     ; check rb4
                 goto ROTATE         ; rb4 = 1
                 goto BINCNT         ; rb4 = 0
ROTATE:
                  Rrncf PORTD, 1        ; rotate right port D
                 CALL Delay
                  goto loop
BINCNT:
                 INCF PORTD, 1      ; add 1 to port D
                 CALL Delay
                  goto loop

Delay:
                 MOVLW B'11111111'
                 MOVWF CNT2
DELAY2:
                 MOVLW B'11110100'
                 MOVWF CNT1
                 DECFSZ CNT2
                 GOTO DELAY1
                 GOTO FINISH
DELAY1:
                 BSF T0CON, TMR0ON          ;start timer0
                 DECFSZ CNT1
                 GOTO DELAY1
                 GOTO DELAY2
FINISH:
                 return


         end                          ; end of program

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body