Embedded Systems Architecture

Newlib printf

Writing pre-formatted strings is not the most ideal API to access a serial port to provide debug messages. Application developers would most certainly prefer if the system exposed a standard C printf function. When the toolchain includes an implementation of a standard C library, it usually gives you the possibility to connect the standard output of the main program to a serial interface. Luckily enough, the toolchain in use for the reference platform allows us to link to newlib functions. Similar to what we did in Chapter 5, Memory Management, using the malloc and free functions from newlib, we provide a backend function called _write(), which gets the output redirected from the string formatted by all the calls to printf() ...