please dont rip this site

PIC Microcontoller Delay Method

Delay X cycles (n-x) exclusive

from Nikolai Golovchenko

;-----------------------------------------------------------
;d0, d1, d2, ...dn      - counters
;d0 = 0..3              - least significant 2 bits
;d1,...dn = 0..255      - more significant 8, 16, 24, ... bits
;
;Total Delay =
;= d0+4*d1+4*256*d2+4*256*256*d3...+4*256^(n-1)*dn + overhead
;
;Overhead depends on a number of counters, see below

;First preincrement all counters except d0
;overhead = n cycles
        incf d1, f
        incf d2, f
        ...
        incf dn, f
;2 bit delay (d0 - 1 cycle resolution)
;overhead += 4 cycles
        comf d0, w
        andlw 0x03
        addwf PCL, f
Delay64Mx
Delay256Kx
        nop
Delay1Kx
        nop
Delay4x
        nop
;8 bit delay (d1 - 4 cycle resolution)
;overhead += 2 cycles
        decfsz d1, f
         goto Delay4x

;8 bit delay (d2 - 1024 cycle resolution)
;overhead += 3 cycles
        decf d1, f
        ;change d1 to 255, so previous loop
        ;(from Delay4x) will take
        ;255*4-1=1019 cycles
        ;we need to add 5 more cycles to get 1024.
        ;4 cycles are in this loop and
        ;another 1 cycle is a nop above

        decfsz d2, f
         goto Delay1Kx

;8 bit delay (d3 - 262144 cycle resolution)
;overhead += 3 cycles
        decf d2, f
        ;previous two loops (from Delay4x) will take
        ;1019+255*1024-1=262138 cycles
        ;we need to add 6 more cycles to get 262144.
        ;4 cycles are in this loop and
        ;another 2 cycles are above - two nops

        decfsz d3, f
         goto Delay256Kx

;8 bit delay (d4 - 262144*256 cycle resolution)
;overhead += 4 cycles
        decf d3, f
        ;previous two loops (from Delay4x) will take
        ;262138+255*262144-1 cycles
        ;we need to add 7 more cycles to get 4*256^3.
        ;5 cycles are in this loop and
        ;another 2 cycles are above - two nops
        nop
        decfsz d4, f
         goto Delay64Mx

;at this point we have a 34 bit one cycle resolution delay!
;Total Delay = overhead + 0..1.7e10 cycles
;overhead = 4+4+2+3+3+4 = 20 cycles
;-----------------------------------------------------------

And the same for a SX chip:

;-----------------------------------------------------------
;d0, d1, d2, ...dn      - counters
;d0 = 0..3              - least significant 2 bits
;d1,...dn = 0..255      - more significant 8, 16, 24, ... bits
;
;Total Delay =
;= d0+4*d1+4*256*d2+4*256*256*d3...+4*256^(n-1)*dn + overhead
;
;Overhead depends on a number of counters, see below

;First preincrement all counters except d0
;overhead = n cycles
        inc d1
        inc d2
        ...
        inc dn
;2 bit delay (d0 - 1 cycle resolution)
;overhead += 5 cycles
        mov w, /d0
        and #$03
        add PC, w
Delay256Kx
        nop
Delay64Mx
        nop
Delay1Kx
        nop
;8 bit delay (d1 - 4 cycle resolution)
;overhead += 2 cycles
Delay4x
        decsz d1
         jmp Delay4x

;8 bit delay (d2 - 1024 cycle resolution)
;overhead += 3 cycles
        dec d1
        ;change d1 to 255, so previous loop
        ;(from Delay4x) will take
        ;255*4-2=1018 cycles
        ;we need to add 6 more cycles to get 1024.
        ;5 cycles are in this loop and
        ;another 1 cycle is a nop above

        decsz d2
         jmp Delay1Kx

;8 bit delay (d3 - 262144 cycle resolution)
;overhead += 3 cycles
        dec d2
        ;previous two loops (from Delay4x) will take
        ;1018+255*1024-2=262136 cycles
        ;we need to add 8 more cycles to get 262144.
        ;5 cycles are in this loop and
        ;another 3 cycles are above - three nops

        decsz d3
         jmp Delay256Kx

;8 bit delay (d4 - 262144*256 cycle resolution)
;overhead += 6 cycles
        dec d3
        ;previous two loops (from Delay4x) will take
        ;262136+255*262144-2 cycles
        ;we need to add 10 more cycles to get 4*256^3.
        ;8 cycles are in this loop and
        ;another 2 cycles are above - two nops

        jmp $+1
        decsz d4
         jmp Delay64Mx

;at this point we have a 34 bit one cycle resolution delay!
;Total Delay = overhead + 0..1.7e10 cycles
;overhead = 4+5+2+3+3+6 = 23 cycles
;-----------------------------------------------------------

This is probably too small for SX :)

Code:


file: /Techref/microchip/delay/xb1crnm-ng.htm, 7KB, , updated: 2005/3/28 20:03, local time: 2024/12/14 01:07,
TOP NEW HELP FIND: 
18.97.14.91:LOG IN

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://techref.massmind.org/Techref/microchip/delay/xb1crnm-ng.htm"> PIC Microcontoller Delay Method - Delay X cycles (n-x) exclusive</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

 

Welcome to massmind.org!

 

Welcome to techref.massmind.org!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .