how could i change my UART baud

Fischer I already found this answer .. but never success with this way...

I suggest :

In Quartus II v6.0 Handbook -> embedded peripherals.

You could find this for UART baudrate configuration :

divisor=int((clok freq/baudrate)+0.5)

According to your clock freq and the baudrate you want, write into the divisor :

IOWR_ALTERA_AVALON_UART_DIVISOR(uart_base_addr, new_divisor);

don't forget to allow modification of divisor in SOPC Builder

you can also read your divisor with IORD_ALTERA_AVALON_UART_DIVISOR..

You don't need to open a file descriptor on the uart IP device

example :

clock freq : 50Mhz

baudrate : 921600 bds

divisor = 54