Code generator for Delays by Nikolai Golovchenko Wow!
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PIC 16 Delay Tutorial by Vasily Koudymov
Delay Subroutines
Are there simulation problems with delays?
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
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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
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