Hi,
please look at the functions fprintf, fscanf, fgetc, fputc, fgets and fputs. All these functions are implemented in newlib, but unfortunately, I do not have any experience with read/write data from/to file using micro and I am afraid you have to modify these functions or add some functionality manually. I found some information how to read/write to file using Arduino, so I think it should be also possible using MPC5748G, but I am not able to provide any more information.
Please look at the following URL:
Using Newlib in ARM bare metal programs | Freedom Embedded
Regards,
Martin
PS: Do not forget correctly configure UART.
