Problem with UART ADSP-2191

Hi, everyone.

There is the problem with UART adps-2191. I use simple code to transmit a string. To define the THR register emptiness I use polling of the THRE bit (bit 5) in the LSR register. But I see on the oscilloscope screen only last byte (it looks like the next byte overwrites the previous one). Then I insert explicit delay after sending byte and everything works properly (i see the whole string on the oscilloscope screen). I even used the example from the data sheet (hardware reference) but result is the same. What have I done wrong?