Writing .txt file in SD Card - DE2

I just solved my problem and it seems that my altera_up_sd_card_avalon_interface.h and altera_up_sd_card_avalon_interface.c files were outdated. I replaced my files with the ones at ftp://ftp.altera.com/up/pub/altera_material/11.0/university_program_ip_cores/ and now it seems to read my files correctly.

Another problem I had was when trying to read characters with value above 127, because the alt_up_sd_card_read returns a short int. Then, I changed its return value to int on altera_up_sd_card_avalon_interface.h and altera_up_sd_card_avalon_interface.c, and at the former, I changed:

* Line 1733 from (char) to (int);

* Line 1680 from char to int;

That resolved my problems, and now I can read values above 127.