PIC Microcontoller Time Method

Delays

Code generator  for Delays by Nikolai Golovchenko Wow!

Timer@

General Delay Methods

Counting Hours Minutes and Seconds

Stack Recursive Delay

PIC 16 Delay Tutorial by Vasily Koudymov

Delay Subroutines

• Delay X cycles (20-271) inclusive from Andrew Warren
• Delay X cycles (11-256) exclusive from Regulus Berdin
• Delay X cycles (7-1030) exclusive from Dwayne Reid
• Delay X cycles (11-327690) inclusive from Mike McLaren
• Delay X cycles (n-x) exclusive from Nikolai Golovchenko
• Delay X cycles (12-65547) for 18F chips by Mike McLaren
• Delay X cycles (7-263) for 18F chips by Scott Dattalo +
• Delay X cycles (0-256) macro by Bob Ammerman
• Delay X cycles (0-256) macro by Myke Predko
• Delay X cycles (0-1024) macro by Mike Harrison
• Delay X micro seconds macro for 14 bit core from Mike McLaren K8LH

Are there simulation problems with delays?

Macro Examples

James Newton says:

I also wrote this god-awful macro for the Parallax SX key asembler that may be of use to someone: It produces the smallest and/or tightest loop delays inline when you call it with the value and units of time you wish to delay for; calculating the number of cycles based on the processor speed. The CpuMhz equate must be adjusted to what ever is right for your chip. It should probably be called CpuMips vice CpuMhz. The only redeming virtue is that it does not use anything other than w (on the SX you can decrement W); no stack use, no register use. :

	device	pins28, pages1, banks8, turbo, stackx, optionx, carryx
	reset reset_entry
CpuMhz = 50
temp	ds	1
usec	EQU	-6
msec	EQU	-3
sec	EQU	1
cycles	EQU	0

mynop	MACRO
	noexpand
	page $>>8
	ENDM

cyclefor MACRO 1
_cycles = \1
IF _cycles > 0
_temp	=	$//4
IF _temp = 2
 IF _cycles <5 
	REPT _cycles 
	expand 
	mynop 
	noexpand 
	ENDR _cycles = 0 
  ELSE 
	expand 
	mynop 
	noexpand 
	_cycles = _cycles -1 
	ENDIF 
    ENDIF 
IF _temp = 1 
    IF _cycles < 6 
	REPT _cycles 
	expand 
	mynop 
	noexpand 
	ENDR 
	_cycles = 0 
    ELSE 
	expand 
	mynop 
	mynop 
	noexpand 
	_cycles = _cycles -2 
	ENDIF 
    ENDIF 
IF _cycles > 3
	expand
	 mov w, #_cycles / 3
	 decsz 1	;dec w
	 clrb 2.1       ;modify PC to jump back
	noexpand
 _cycles = _cycles // 3 ;cycles left over
 ENDIF
IF _cycles > 0
  REPT	_cycles
	expand
	 mynop
	noexpand
   ENDR
 ENDIF
ENDIF
	ENDM

reset_entry
	mov w,#$7F
	mov !OPTION,w

delayhelp MACRO
	ERROR 'USAGE: delay value, [usec,msec,sec,cycles]'
	ENDM

delay	MACRO	2
noexpand
IF (\2=usec OR \2=msec OR \2=sec) AND (\1<1000 AND \1>0)
 IF \2=sec
  _cycles = (\1 * 1000000 / (1000/CpuMhz))
  ENDIF
 IF \2=msec
  _cycles = (\1 * 1000 / (1000/CpuMhz))
  ENDIF
 IF \2=usec
  _cycles = (\1 / (1000/CpuMhz))
  ENDIF
 IF \2=cycles
  _cycles = \2
  ENDIF
 IF _cycles = 0
  expand
	 ;delay less than one cycle at this processor speed'
  noexpand
 ELSE
  IF _cycles > 255
   REPT (_cycles / 256)
    cyclefor 256
    _cycles = _cycles - 256
    ENDR
   ENDIF
  cyclefor _cycles
  ENDIF

ELSE
	delayhelp
ENDIF
	ENDM

	delay 999, usec
	delay 200, usec
	delay 250, usec
	delay 10, usec
	delay 20, usec
	delay 100, msec

See Also:

• http://www.skyinet.net/~ecb/#delay1

See:

Archive:

• PICList post "18F delay"
• PICList post "Clever 3-cycle delay?" +
• PICList post "Delay loops that don't need any RAM"

Questions:

Code:

• try this for 1 to 117million cycle delay
  
  
  delay	macro	Cycles
   variable CyclesLeft ,LoopCycles,d_used           ;  Keep Track of Remaining Cycle
   local	iloop
  CyclesLeft = Cycles
  
  	if CyclesLeft > .327680 ; 0x5 * 0xffff
  d_used = 3
  	else
  	 if Cycles > 3*0xFF
  d_used = 2
  	 else
  d_used = 1
  	 endif
  	endif
  
  
  	if	d_used == 3
  LoopCycles = (Cycles-6-.10) / 7
  CyclesLeft = (Cycles-6-.10) - (LoopCycles*7)
  
  	endif
  	if	d_used == 2
  LoopCycles = (Cycles-4-6) / 5
  CyclesLeft = (Cycles-4-6) - (LoopCycles*5)
  	
  	endif
  
  
    if Cycles >=5
  	if	d_used == 1
  LoopCycles = (Cycles-2-2) / 3
  CyclesLeft = (Cycles-2-2) - (LoopCycles*3)
  	endif
  
   	movlw   (LoopCycles & 0xFF)+1
    	movwf   STACK-0
  	if d_used >=2
   	movlw   ((LoopCycles>>8) & 0xFF)+1
    	movwf   STACK-1
  	endif
  	if d_used >=3
  	if ((LoopCycles>>.16) > .255 )
   error "Required Delay is longer than 'delay' Macro can support"
  	endif
   	movlw   ((LoopCycles>>.16) & 0xFF)+1
    	movwf   STACK-2
  	endif
  iloop
   	if d_used >=3
  	 goto	$+1 
  	endif
   	if d_used >=2
  	 goto	$+1 
  	endif
  
    	decfsz  STACK-0,F
     	 goto	iloop
   	if d_used >=2
    	decfsz  STACK-1,F
     	 goto	iloop+1
  	endif
  	if d_used >=3	
  	decfsz  STACK-2,F
     	 goto	iloop+2
  	endif
  	
  
    endif
  
   while CyclesLeft >= 2          ;  Put in 2 Instruction Cycle Delays
    	goto    $ + 1
  CyclesLeft = CyclesLeft - 2
   endw
   if CyclesLeft == 1             ;  Put in the Last Required Cycle
    	nop
   endif
          endm

  +

Comments:

• DELAY
  MOVLW 0Xf45
  MOVWF sayac1
  L2 MOVLW 0XF1
  MOVWF SAYAC2
  L1 DECFSZ SAYAC2, 1
  GOTO L1
  DECFSZ SAYAC 1
  GOTO L2
  RETURN
  +

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