Hello Stefan:

Glad to hear you fixed your read and write issues. When you try to use scanf I believe that you will have the compiler and linker trying to include floating point from the C library. Some things to consider...

1) Does your C compiler package include the floating point library?

2) Does the particular microcontroller that you are using have enough code memory to hold the whole program? Linking in code for scanf can make the resulting object file quite a bit larger and may be an issue for small memory microcontrollers.

3) Are you using an evaluation version of a tool set that limits the size of the program you can make to 2K or some other small size? The larger code size needed for scanf may cause you to exceed the limit.

Michael Karas