[CM3]UART always lose the last char

Hi,there.

I am using UART of my CM3 board,and there is something strange.

I use minicom(a friendly serial communication program for linux) to Rx data came from CM3,and every thing goes well except that the last char is always lost. I have followed my program step by step through j-link and it works very very very well,but once let CM3 runs at normal state(no halt,no step by step),the problem comes again.Can someone help me?Thanks.

Best regards.