topic Re: printf problem in ColdFire/68K Microcontrollers and Processors

printf problem

LPs1978 — Fri, 17 Jul 2009 20:29:27 GMT

Hi all,

I'm in triuble with printf. I'm trying to use the printf standard funcion, but each time I want to use it the linker give me errors. It tells me that it cannot find UART function. I think that this is a problem of the console support, but I have not idea how to disable it.

How I can tell toi the linker to not use UART functions?

Thanks in advance

Re: printf problem

LPs1978 — Mon, 20 Jul 2009 15:39:49 GMT

Has someone news about my problem?

There is a way to use the stdout with printf instead of console without recompile libraries?

Message Edited by LPs1978 on 2009-07-20 09:40 AM

Re: printf problem

admin — Mon, 20 Jul 2009 16:30:10 GMT

Macro using fprintf() function can be used as a simple workaround.

Switching stdout from UART console to another device is OS-specific. For example, well-known uC/OS uses i/O library function ReplaceStdio().

Re: printf problem

LPs1978 — Mon, 20 Jul 2009 16:55:47 GMT

Sorry,

my problem is to use the pritf as stadard output. In other words I need to modify the stdout->write_proc to a my proprietary procedure.

What is happening to me is that I include stdio.h an when I use printf the sistem calls WriteUARTN funztion instead of my procedure.

I think that the problem is that the library wants to send to UART the output instead of stdout file structure.

What I can do to solve my problem??

Re: printf problem

admin — Mon, 20 Jul 2009 17:38:30 GMT

Is overloading stdout->write_proc with your proprietary procedure succeed?

Re: printf problem

LPs1978 — Mon, 20 Jul 2009 18:34:53 GMT

Yes! with the following istrunction:

stdout->write_proc = Write_Display;

But teh firmware continue to call WriteUARTN and not my Write_Display function.

Where is my error????

Re: printf problem

LPs1978 — Tue, 21 Jul 2009 14:05:51 GMT

Probably I found out the problem.

I debugged my firmware and I saw that when the istruction

stdout->write_proc = Write_Display;

is executed the stdout->write_proc value doesn't change and still at value 0.

The stdout structure is allocated in RAM.

What can cause this strange behaviour?

Thanks in advance for you support.

Re: printf problem

LPs1978 — Tue, 21 Jul 2009 16:21:58 GMT

Some others news to stress you men.

If I watch at the address of stdout->write_proc using view-global variables codewarrior function the value is 0x200006E4.

In my code, if I read the address using instruction

__io_proc *Pippo = &stdout->write_proc;

the address is totally different. The address that I read is 8 byte more high instead of the real one:

0x200006EC.

Than when I the firmware executes the istruction

stdout->write_proc = Write_Display;

it modify another part of stdout structure.

This means that the software is compiling something different instead of stdout file structure.

Have you got any idea to make me able to run the printf correctly????

Message Edited by LPs1978 on 2009-07-21 10:38 AM

Re: printf problem

LPs1978 — Tue, 21 Jul 2009 18:37:35 GMT

I'm back to stress you.

At the end I found the problem of FILE structure. In ansi_prefix_CF.size.h was defined no tiny library, but for MCF52221 is mandatory to use C_4i_CF_SZ library that is a small size one.

Now the write_proc is set correctly, but my write function isn't colled.

Is the tiny library able to make me use printf???