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Author Topic: More delays  (Read 3634 times)
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robban
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« on: July 17, 2007, 10:26:55 22:26 »

Hi there!

Here comes a shorter delay inline routine:
;Routine for calculating a precise delay in MPASMWIN(or command-line MPASM). ;Use it as inline assembly unless You
;coding solely in ASM
;It's blistering fast. Don't forget to change the value for at least cblock,d1,d2 and d3 according
;to Yr. specifics. Also remember that the PIC operates at one quarter of the crystal speed(Fosc). The resulting HEX-
;code is 154 byte(beat that!)

;Some BASIC or C/C++ code

;=======Delay.ASM=======================================================================
;This code block is here for the sake of clarity, because You can't compile the rest without it

        processor 16F876A               ;or whatever
        #include C:\MPASMAssembler\p16f876a.inc      ;(use Yr. own path)
        radix   hex                   ;Redundant really, since hex is default,
        __config _WDT_OFF & _CP_OFF & _LVP_OFF & _HS_OSC   ;You can also use 'b' for binary,'d' for decimal or an ASCII character enclosed in
                            ;single quotes. Just put it anywhere in the code.
                      ;(Fuses are found at the bottom of the .INC files)
                         
   __idlocs 0x4455                ;Choose Yr. own ID. The PIC18 series
                     ;can also specify address and their content
       


; Delay = 0.5 seconds(choose Yr. own)
; Clock frequency = 20 MHz, 5 MIPS(an example)

; Actual delay = 0.5 seconds = 2500000 cycles
; Error = 0 % (Well, if You use a precise clock crystal at 32.768 kHz, then You must change _HS_OSC to _XT_OSC)
;=======================================================================================
_asm
   cblock 0x3   ;loop 3 times(cblock is a way to create run-time variables in assembler)
   d1
   d2
   d3
   endc      ;must end a cblock statement

         
   movlw   0x16   ;charge variable d1 with 16hex
   movwf   d1
   movlw   0x74   ;charge var d2 with 74hex
   movwf   d2
   movlw   0x06   ;charge d3 with 6h
   movwf   d3   ;total of 2499999 cycles
Delay_0
   decfsz   d1, f   ;You can read about this technique in the MPASM manual in MPLAB IDE
   goto   $+2
   decfsz   d2, f
   goto   $+2
   decfsz   d3, f
   goto   Delay_0

   nop      ;1 cycle
   
_endasm

;More BASIC or C/C++ code

   END ;Or end, You can always declare case-sensitive in MPASMWIN

;/Cheers, Robban
« Last Edit: July 18, 2007, 06:08:06 18:08 by robban » Logged

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