When I try to pass arguments in a function it does not work properly?

[jessemayfield]

I have a function declared as follows:

void Build_API_Tx_Frame ( unsigned char frame_type, unsigned char *payload, unsigned char, payload_size);

{

Tx_Frame_Type = frame_type;

...

No need to type the rest  of the function here...

...

}

When I call this function in my main routine, Tx_Frame_Type does not get passed correctly, it retains a value of zero when I step through in the debugger.

The other arguments being passed, *payload, and payload_size are passing and updating as expected.

Any help would be greatly appreciated.

[trytohelp]

Hello Jesse,

What is the toll version used and the architecture (device) ?

For my understanding it should be linked to an optimization.

Can you check how the Tx_Frame_Type variable is declared ?

      - is it global function or local one ?

      - can you try to defined it as volatile ?

          in some case the volatile keyword breaks the optimization

Have a great day,
Pascal
NXP Technical Support

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[jessemayfield]

Tx_Frame_Type is declared as "unsigned char" and is global variable.

I am using Codewarrior IDE v5.9.0.

The processor being used is "MC9S12C128".

I will try to define Tx_Frame_Type as volatile - just for confirmation - the syntax for this would be as follows:

volatile unsigned char Tx_Frame_Type = 0;   ?

Thanks in advance!

[ZhangJennie]

Hi,

if Tx_Frame_Type is global variable, I suggest you add it to ENTRIES section in prm file to avoid optimization. see how does it work?

Have a great day,
Jennie Zhang

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