Nios-II SOPC UART delivers wrong bytes

there is timing problem.

with UART baudrate = 115200bps and System Clock 48Mhz

SOPC calculate baud error.

that is almost 0.04%(maybe 1byte data loss per 20byte stream)

but. Set system clock to 50Mhz

that is <0.01%

so, I have set system clock to 50Mhz, and test some long UART datastream. (50Kbyte)

that looks perfect.(single thread test)

now I have two problems.

one is how to check datastream end.(for now using timeout method)

the other is testing in multi thread environment.