;=======pwm.ASM=================================15/11/06==
; Standard INTRC_OSC_NOCLKOUT 4MHz
; http://www.module.ro
; © Copyright 2006 Bergthaller Iulian-Alexandru
;------------------------------------------------------------
;     configure programmer
     LIST       P=16F628      ; f=inhx8m
     #include   "P16F628.INC" ; Include header file
     __CONFIG   _PWRTE_ON  & _WDT_OFF & _XT_OSC & _BODEN_ON & _LVP_OFF & _CP_OFF & _MCLRE_OFF
                              ; (_INTRC_OSC_NOCLKOUT)
;------------------------------------------------------------
     cblock  0x20             ; Beginn General Purpose-Register
;-------------------------- counters
         count1
         count2
         count3
;--------------------------
     endc
;--------------------------
#DEFINE  pwmu   PORTB,3
;--- Reset --------------------------------------------------
     org     h'00'
     goto    init             ; reset -> init
;--- Interrupt ----------------------------------------------
     org     h'04'
;--------------------------
init
     clrf    PORTA
     clrf    PORTB
     movlw   0x07             ; Turn comparators off
                              ; and enable pins for I/O .
     movwf   CMCON       
     bcf     STATUS,RP1
     call    usi              ;  port settings
     call    pause
;     movlw   0xFF
;     movwf   PORTB
     bsf     PORTB,3
     call    pause            ; wait 126ms
     call    set_timer

;-------------------------- 
uu     
     call    pause
     movlw   0x02             ; set pwm at 2/256
     movwf   CCPR1L
     call    pause            ; wait 126ms
     movlw   0x10
     movwf   CCPR1L           ; set pwm at 10/256
     call    pause
     movlw   0x40
     movwf   CCPR1L
     call    pause
     movlw   0x80
     movwf   CCPR1L
     call    pause
     movlw   0xFF             ; max. power
     movwf   CCPR1L
     call    pause
     movlw   0x80
     movwf   CCPR1L
     call    pause
     movlw   0x40
     movwf   CCPR1L
     call    pause
     movlw   0x10
     movwf   CCPR1L
     goto    uu               ; repeat

;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
set_timer
     clrf    T2CON
     clrf    TMR2
     clrf    INTCON
     bsf     STATUS,RP0
     clrf    PIE1
     bcf     STATUS,RP0
     clrf    PIR1
     bsf     STATUS,RP0
     movlw   0xFF
     movwf   PR2              ; compare with 255
     bcf     STATUS,RP0
     movlw   0x02
     movwf   CCPR1L
     movlw   0x03
     movwf   T2CON            ; prescaler 1:16 and postscaler 1:1
     movlw   0x3C
     movwf   CCP1CON
     bsf     T2CON,TMR2ON     ;turn on timer, see pic16f628 datasheet
     return

;************************************************************************
;     Delay                                                                      *
;************************************************************************
pause
     movlw   0x02             ; 126 ms     
     movwf   count3
d3
     movlw   0x3F             ; 63 ms
     movwf   count1
d1
     movlw   0xFA             ; 1ms  
     movwf   count2
d2
     nop
     decfsz  count2,F     
     goto    d2          
     decfsz  count1,F     
     goto    d1          
     decfsz  count3,F    
     goto    d3          
     retlw   0x00
;============================================================
usi
     bsf     STATUS,RP0       ; Bank 1
     movlw   0xFF             ; all input
     movwf   TRISA
     movlw   0x00
     movwf   TRISB            ; all output
     bcf     STATUS,RP0       ; Bank 0
     return
;============================================================
     end
;============================================================