Delay Routines by Jan Huygh of Brussels
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;****************************************************************************** ;_Delays.asm Version 0.0a ;****************************************************************************** ; ;Written for : Atmel "AVR Assembler" and "AVR Assembler 2" ; when : 2005 November 20 ; where: BRUSSELS - BELGIUM - EUROPE ; who : Jan Huygh ; E-mail: jan.huygh@skynet.be ;****************************************************************************** ;A WORD FROM THE AUTHOR : ; ;I would find it motivating to find out that people use this code. ; ;On regular base (every 10 to 12 weeks) I gather the comments on the code I ;posted and use the comments to improve my code. If you have constructive ;comment then let me know. ; * Give me an evaluation. ; * Send me a mail (jan.huygh@skynet.be) subject "I use your _Delays.asm". ; * Send me a mail (jan.huygh@skynet.be) subject "Comment on your _Delays.asm" ;****************************************************************************** ;ABOUT VERSION 0.0a ; ;This is the first posted version. ; ; KNOWN BUGS : ; * None so far ; OPPORTUNITIES FOR IMPROVEMENT : ; * a version that can be used as a subroutine taking in to acount the time ; for the call and for the return. ; * a version that takes the input from the stack so it can take a variable ; for the input. ; * a version that is less precise but takes less bytes of program memory ; ;****************************************************************************** ;.INCLUDE "_Delays.asm" enables you to use the following macro in your code ; ; _Waiste_us n ; With (1.000.000/F_CPU) <= n <= 25769803779/Your_CPU_frequency_in_MHz ; ; This macro will generate a wait loop from 1 µs to 25.769.803.779 µs ; Depending on the CPU-speed set in F_CPU here below you will need to ; respect a minimum value for n. (n_minimum) = 1.000.000/F_CPU). ; This is needed because we can not loop for less then 1 ; instruction cycle. ; 25.769.803.779 µs, that's over 3h30 when you use a CPU running at 20 MHz. ; _Waiste_us is absolutely exact down to (1/Your_CPU_frequency_in_MHz) µs ; _Waiste_us will pick the smallest code for your delay (Maximum 13 words) ;****************************************************************************** ;How to use this in your code : ; ; A) Pick the correct ".equ F_CPU = x" statement ; AND ; save this file to your disk ; ; B) Make sure it is in the same folder as the other files of your current project ; OR ; Make sure the folder where you saved this file is referenced in the ; assembler options (Project=>Assembler Options=>Additional include path) ; ; C) Include the statement .INCLUDE "_Delays.asm" at the top of your program ; ; D) Use the statement _Waiste_us n, in your code ; ;Here is a code example : ; ; .INCLUDE "_Waiste.asm" ;Make the macro _Waiste_us n available in your code ; _Waiste_us 100 ;loop for 100 µs (that's 0,1 ms) ; _Waiste_us 16000 ;loop for 16.000 µs (that's 16 ms) ; _Waiste_us 7000000 ;loop for 7.000.000 µs (that's 7 s ) ; ;****************************************************************************** ;The CPU-speed needs to be set before you can use _Waiste_us. ;Find your CPU-speed in the list here below and uncomment it (remove the ";") ;then press Ctrl^S to save to disk otherwise the include file used by AVR studio ;will be the unchanged version on your disk. ; ; ; .equ F_CPU = 1000000;Hz ; .equ F_CPU = 2000000;Hz .equ F_CPU = 3579545;Hz ; .equ F_CPU = 3686400;Hz ; .equ F_CPU = 4000000;Hz ; .equ F_CPU = 4032000;Hz ; .equ F_CPU = 4096000;Hz ; .equ F_CPU = 4194304;Hz ; .equ F_CPU = 4433619;Hz ; .equ F_CPU = 4915200;Hz ; .equ F_CPU = 5000000;Hz ; .equ F_CPU = 5068800;Hz ; .equ F_CPU = 5990400;Hz ; .equ F_CPU = 6000000;Hz ; .equ F_CPU = 6144000;Hz ; .equ F_CPU = 6500000;Hz ; .equ F_CPU = 7372800;Hz ; .equ F_CPU = 7680000;Hz ; .equ F_CPU = 8000000;Hz ; .equ F_CPU = 9000000;Hz ; .equ F_CPU = 9216000;Hz ; .equ F_CPU = 9830400;Hz ; .equ F_CPU = 10000000;Hz ; .equ F_CPU = 10240000;Hz ; .equ F_CPU = 11000000;Hz ; .equ F_CPU = 11059200;Hz ; .equ F_CPU = 11520000;Hz ; .equ F_CPU = 12000000;Hz ; .equ F_CPU = 12000393;Hz ; .equ F_CPU = 12288000;Hz ; .equ F_CPU = 13500000;Hz ; .equ F_CPU = 14318180;Hz ; .equ F_CPU = 14745600;Hz ; .equ F_CPU = 15000000;Hz ; .equ F_CPU = 15360000;Hz ; .equ F_CPU = 16000000;Hz ; .equ F_CPU = 16000312;Hz ; .equ F_CPU = 16257000;Hz ; .equ F_CPU = 16384000;Hz ; .equ F_CPU = 17734475;Hz ; .equ F_CPU = 18000000;Hz ; .equ F_CPU = 18432000;Hz ; .equ F_CPU = 19660800;Hz ; .equ F_CPU = 20000000;Hz .Macro _Waiste_us;n ; Calculate the number of CPU-cycles needed to generate the requested delay ; taking in to account the frequency you are using for your CPU. ; You can simplify the next 9 lines of code before "_Cycle_Waister Cycles_Needed" ; to "Cycles_Needed = @0 * F_CPU / 1000000". If you do so _Waist_us will ; generate the exact delay you requested or the delay obtained by executing the ; number of cpu-cycles that brings just less then the delay you requested. ; This might be a good option if you need a certain delay but need to be sure ; you never have a delay that is even a fraction of a CPU-cycle longer than the ; delay you requested. ; The 9 lines of code here below do NOT use any space in the actual program ; memory of your AVR. ; The code here below will actually pick the number of CPU-cycles needed to ; generate EXACTLY the delay you requested and when that can not be achieved ; it will select the number of cycles that generate the delay that is the best ; approximation for the delay you requested even if that is just above the ; delay you requested. .set Fraction = @0*F_CPU/1000000 ; .set Fraction = Fraction * 100 .set Fraction = @0*F_CPU/10000 - Fraction .if Fraction >= 50 .equ Cycles_Needed = (@0 * F_CPU /1000000)+1 .endif .if Fraction < 50 .equ Cycles_Needed = (@0 * F_CPU /1000000) .endif _Cycle_Waister Cycles_Needed .endmacro .macro _Cycle_Waister .If @0 == 1 nop .EndIf .If @0 == 2 nop nop .EndIf .If ((@0 > 2) && (@0 < 769)) ;C=3n ;769=(3 * (2^8)) + 1 .set Loops_Needed = @0/3 ldi R16,Low(Loops_Needed) Loop: dec R16 brne Loop .set Cycles_Left_To_Do = @0 - (3*Loops_Needed) _Cycle_Waister Cycles_Left_To_Do .EndIf .If (@0 > 768) && (@0 < 262146) ;C=1+4n ;262146 = 1 + (4 * 2^16) + 1 .set Loops_Needed = (@0 - 1)/4 ldi ZL,Low(Loops_Needed) ldi ZH,High(Loops_Needed) Loop: sbiw ZL,1 brne Loop .set Cycles_Left_To_Do = (@0 - (4*Loops_Needed))-1 _Cycle_Waister Cycles_Left_To_Do .EndIf .If (@0 > 262145) && (@0 < 83886083) ;C=2+5n ;83.886.083 = 2 + (5 * 2^24) +1 .set Loops_Needed = (@0 - 2)/5 ldi R16,Low(Loops_Needed) ldi ZL,Byte2(Loops_Needed) ldi ZH,Byte3(Loops_Needed) Loop: subi R16,1 sbci ZL,0 sbci ZH,0 brne Loop .set Cycles_Left_To_Do = (@0 - (5*Loops_Needed))-2 _Cycle_Waister Cycles_Left_To_Do .EndIf .If (@0 > 83886082) && (@0 < 25769803780) ;C=3+6n ;25769803780 = 3 + (6 * 2^32) +1 .set Loops_Needed = (@0 - 3)6 ldi XL,Low(Loops_Needed) ldi XH,Byte2(Loops_Needed) ldi ZL,Byte3(Loops_Needed) ldi ZH,Byte4(Loops_Needed) Loop: sbiw Xl sbci ZL,0 sbci ZH,0 brne Loop .set Cycles_Left_To_Do = (@0 - (6*Loops_Needed)) - 3 _Cycle_Waister Cycles_Left_To_Do .endif .endmacro |