printf doesn't work

printf() outputs through putchar() which usually outputs to a single I/O device. Does your putchar() allow for multiple I/O devices? How do you switch between them?

"printf() outputs through putchar()..."

http://www.keil.com/support/man/docs/ca/ca_printf.htm

"... which usually outputs to a single I/O device."

You will need to consult your compiler Manuals (specifically, the Library section) to find out the specific requirements of the particular putchar() implementation.

I wouldn't be surprised if GCC requires you to do some sort of "device open" for the UART; I have no idea for RealView - you'll have to read that one up for yourself!

I did sweep over the manuals for my compiler (http://www.keil.com/support/man/docs/ca/ca_putchar.htm ) but I can't find any thing valuable in there. Because of that I put my problem on a forum. I know Please read the manual sometimes works but not in this case…

http://www.keil.com/support/man/docs/ca/ca_putchar.htm

As it suggests on that page, you'll have to modify the source to provide the functionality you require.

"but I can't find any thing valuable in there."

Eh???

http://www.keil.com/support/man/docs/ca/ca_putchar.htm says:

"Source code is provide in the LIB folder."

See also http://www.keil.com/support/man/docs/ca/ca_lib_source.htm

You have the complete source code, so you can see exactly what it's doing, and modify it to your requirements!

http://www.keil.com/support/docs/2014.htm

http://www.keil.com/download/docs/288.asp