Hello, thanks to everybody for your comments and help. I found out what was the problem in MSP430x15x,16x,161x Errata's description file. Here is a quote:
US14 - Bug description: (PRELIMINARY) Module: USART0, USART1, UART Mode: Lost character start edge When using the USART in UART mode with UxBR0 = 0x03 & UxBR1 = 0x00, the start edge of received characters may be ignored due to internal timing conflicts within the UART state machine. This condition does not apply when UxBR0 is > 0x03. Workaround: (In progress) Mindaugas
