_nop_ () does not work

[hal2003]

Posted on September 08, 2005 at 07:08

_nop_ () does not work

[hal2003]

Posted on September 07, 2005 at 11:43

Hi forum!

Second topic today. Think today is not my day.

I need a small delay in a program. Thus I added _nop_ (); in the source code. But it didn't work. So I wrote the following lines in the main function where x is an IO pin:

while(1)

{

x = 1;

_nop_ ();

x = 0;

_nop_ ();

}

Only the second _nop_ () causes a delay. The first one is just ignored. I use µVision2 from Keil.

Thanks Oliver

[najoua]

Posted on September 07, 2005 at 12:24

Hello,

This works fine.

Did you check the generated code? Are the NOP instructions in the LST file?

Regards,

[hal2003]

Posted on September 07, 2005 at 14:43

Here's the code:

ASSUME DPP3 : SYSTEM

EXTRN ?C_STARTUP : FAR

REGDEF R0 - R15

?PR?SLREGELUNG SECTION CODE WORD 'FCODE'

; line 1: #pragma large

; line 2: #pragma src

; line 3: #pragma MOD167 FIX167

; line 4:

; line 5: #include ''intrins.h''

; line 6: #include ''regst10F269.h''

; line 7: #include ''absacc.h''

; line 8: #include ''math.h''

; line 9:

; line 10: sbit Testpin = P3^7;

; line 11:

; line 12: #include ''stdio.h''

; line 13:

; line 14: void main(void)

main PROC FAR

GLOBAL main

; FUNCTION main (BEGIN RMASK = @0x8000)

; line 15: {

; line 16: DP3 = 0x00C0;

MOV DP3,#192

; line 17:

; line 18: while(1)

?C0003:

; line 19: {

; line 20: Testpin = 1;

BSET Testpin

; line 21: _nop_();

NOP

; line 22: Testpin = 0;

BCLR Testpin

; line 23: _nop_();

NOP

; line 24: }

JMP cc_UC,?C0003

; FUNCTION main (END RMASK = @0x8000)

main ENDP

?PR?SLREGELUNG ENDS

; line 25: }

; line 26: // E N D E -----

; line 27:

; line 28:

END

And here's a link to the signal I get: http://img141.imageshack.us/my.php?image=signal9bi.jpg

[ This message was edited by: olfab on 07-09-2005 18:14 ]

[najoua]

Posted on September 08, 2005 at 07:08

Hello,

As you can see both NOP's are in the code.

So I guess since you have just a JUMP at the end, you need to add more than just ONE NOP to see a delay.

I hope this helps you,

Regards,