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 Using the AVR JTAG ICE and AVRISP ISP programmer
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sohomcu

4 Posts
Posted - 09/20/2007 :  00:14:54  Show Profile
Dear all,

Would anyone please help to solve my problem on using CodeVision
C compiler.

I need to pass a variable parameter to the function delay_us( )
which only accept constant expression.
Is it possible?

Thanks a lot

Eddy Lau
Reply #1

ZLM

2945 Posts
Posted - 09/20/2007 :  07:18:37  Show Profile
Did you try cast the varible?

Example:

unsigned char delayInMs;

delay_us((const unsigned char) delayInMs);
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Reply #2

sohomcu

4 Posts
Posted - 09/21/2007 :  02:15:02  Show Profile
I tried your suggestion but it produce an error of invalid
typecast.

Just can't understand why the function delay_ms( ) can accept variable as parameter but delay_us( ) cannot.

What's the purposeof making this limitation?
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Reply #3

ZLM

2945 Posts
Posted - 09/21/2007 :  14:30:29  Show Profile
What is the delay_us() function prototype looks like?
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Reply #4

sohomcu

4 Posts
Posted - 09/22/2007 :  23:36:17  Show Profile
the content of delay.h is as follows:

// CodeVisionAVR C Compiler
// (C) 1998-2000 Pavel Haiduc, HP InfoTech S.R.L.

#ifndef _DELAY_INCLUDED_
#define _DELAY_INCLUDED_

#pragma used+

void delay_us(unsigned int n);
void delay_ms(unsigned int n);

#pragma used-

#endif

I wonder whether this is compiler bug or not?

Who can tell me the answer?

Thanks
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Reply #5

ZLM

2945 Posts
Posted - 09/23/2007 :  23:06:26  Show Profile
It looks fine but I do not know what is "#pragma used+" for.

How about remove those two #pragma lines?
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Reply #6

sohomcu

4 Posts
Posted - 09/23/2007 :  23:34:50  Show Profile
I am sure the problem has nothing concerned with the two
#pragma lines.

Anyway, thanks for your kind concern to my problem.
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