this is refer to discuss no 17250
I just want to share how to set the UART2 & UART3 register, after reading further the datasheet, the UART2 & UART3 can you enable with set the Power Connection Register.
/* power UP UART2 & UART3 */ LPC_SC->PCONP |= 0x03000000;
and then you can set-up the uart2 or uart3 register without hang. and the port works correctly.