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#define error - Codevision

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beer_bains

Posted: Nov 19, 2010 - 12:27 AM

Joined: Nov 18, 2010
Posts: 103
Location: Auckland, New Zealand

i am using codevision to write a program for a mega64.

in my definitions i used:

#define input PORTG.0

and then in the program i used:

if (input == 1)
{
do this do that etc
}
but when I compile it gives me an error sayin:
"the first argument of the '.' operator must be of 'struct' or 'union' type" and highlights the 'if' line which refers to the #define input line.

Is there something wrong with my syntax? How can I do this, what am I doing wrong?
searching the net, help files, data sheets hasn't really lead me anywhere so your help will be much appreciated.

Thanks

Mike B

Posted: Nov 19, 2010 - 12:35 AM

Joined: Jun 22, 2004
Posts: 3849
Location: South West Utah, USA

Look up your PORTG<decimal>0 syntax in a C manual. The decimal point has a special meaning in C.

If you want to input from an AVR pin, use the PIN register, not the PORT register. Also use a different method of selecting pin 0.

ezharkov

Posted: Nov 19, 2010 - 12:52 AM

Joined: Jun 21, 2005
Posts: 882
Location: Chicago area, USA

As far as I remember, the CodeVision's portName.pinNumber extension works only for the first 32 registers. PORTG is outside that area. Therefore you have to access it using standard C methods. For example:
#define input ((PORTG & (1 << 0)) != 0)

But as Mike says, make sure that PORTG is really what you want. You say "input", which means that you probably want PING, not PORTG.

Eugene

beer_bains

Posted: Nov 19, 2010 - 01:04 AM

Joined: Nov 18, 2010
Posts: 103
Location: Auckland, New Zealand

ezharkov wrote:

thanks for that. that explains why the codevision picks up portg as an error and not ports a c and d which i also did using the same way.

Mike is also right I want to use PING0. Can I do that the same way as you mentioned:

#define input ((PORTG & (1 << 0)) != 0)

also if you could please write this in binary, like #define input PING = ob_____ that will be a huge help for me to understand this better.

thanks a lot guys. knowledge gained!!

beer_bains

Posted: Nov 19, 2010 - 01:09 AM

Joined: Nov 18, 2010
Posts: 103
Location: Auckland, New Zealand

Mike B wrote:

yes that's right. I should really be using the PIN register. so thanks for that. When you say use a different method. What method could I used??

thank you

ezharkov

Posted: Nov 19, 2010 - 01:09 AM

Joined: Jun 21, 2005
Posts: 882
Location: Chicago area, USA

beer_bains wrote:

write this in binary

Not sure what you mean exactly. Maybe this?
#define input ((PING & 0b00000001) != 0)

beer_bains

Posted: Nov 19, 2010 - 01:23 AM

Joined: Nov 18, 2010
Posts: 103
Location: Auckland, New Zealand

ezharkov wrote:

#define input ((PING & 0b00000001) != 0)

thanks for that. sorry if i'm bein annoying... but from what I understand the above is exactly the same as:
#define input ((PING & (1 << 0)) != 0)

and what this does is it defines 'input' as PING0, ya??

cheers. thanks again.