External read not working

NZ_Design — Tue, 31 Oct 2006 08:15:14 GMT

I have a periperal decleared called pGraphicCTRL.

Writing data to this address works fine.

but I wont to do this.

pGraphicCTRL = pGraphicCTRL | Graphic_CD

This should generate a read and then a write on the data bus. I only get a write.

if I change it to

cControl = pGraphicCTRL;

pGraphicCTRL = cControl | Graphic_CD;

I still only get a write and if I step though the code the cControl = pGraphicCTRL line is not compiled in.

Why?

Is this a optimizer thing if so its great job but not this time. What if my signal lines are different.

How do I get around it.

Can I turn the optimizer off?

Daniel

Re: External read not working

CrasyCat — Tue, 31 Oct 2006 18:59:59 GMT

Hello

Did you define and declare pGraphicCTRL as volatile?

This is the only way you can tell the compiler it should not optimize away memory access to

the variable.

volatile is recommended for all variables, which may change asynchronously from the normal execution flow (i.e. I/O ports, global variables modified in an interrupt functions, global variables modified in different tasks when you are running a multi-tasking application).

CrasyCat

topic External read not working in Classic/Legacy CodeWarrior

External read not working

Re: External read not working