怎么调试的？
把你相关代码发上来帮你看看。

不能通讯，你是采用中断还是轮询？
出现的什么错误？
板子是否支持？
GPIO口有否复用？

//*****************************************************************************
#include "inc/hw_ints.h"
#include "inc/hw_memmap.h"
#include "inc/hw_types.h"
#include "driverlib/debug.h"
#include "driverlib/fpu.h"
#include "driverlib/gpio.h"
#include "driverlib/interrupt.h"
#include "driverlib/sysctl.h"
#include "driverlib/uart.h"
#include "driverlib/rom.h"
#include "grlib/grlib.h"
#include "drivers/cfal96x64x16.h"
//*****************************************************************************
//
//! addtogroup example_list
//!

UART Echo (uart_echo)

//!
//! This example application utilizes the UART to echo text.  The first UART
//! (connected to the USB debug virtual serial port on the evaluation board)
//! will be configured in 115,200 baud, 8-n-1 mode.  All characters received on
//! the UART are transmitted back to the UART.
//
//*****************************************************************************
//*****************************************************************************
//
// The error routine that is called if the driver library encounters an error.
//
//*****************************************************************************
#ifdef DEBUG
void
__error__(char *pcFilename, unsigned long ulLine)
[
]
#endif
//*****************************************************************************
//
// The UART interrupt handler.
//
//*****************************************************************************
void
UARTIntHandler(void)
[
   unsigned long ulStatus;
   //
   // Get the interrrupt status.
   //
   ulStatus = ROM_UARTIntStatus(UART3_BASE, true);
   //
   // Clear the asserted interrupts.
   //
   ROM_UARTIntClear(UART3_BASE, ulStatus);
   //
   // Loop while there are characters in the receive FIFO.
   //
   while(ROM_UARTCharsAvail(UART3_BASE))
   [
       //
       // Read the next character from the UART and write it back to the UART.
       //
       ROM_UARTCharPutNonBlocking(UART3_BASE,
                                  ROM_UARTCharGetNonBlocking(UART3_BASE));
   ]
]
//*****************************************************************************
//
// Send a string to the UART.
//
//*****************************************************************************
void
UARTSend(const unsigned char *pucBuffer, unsigned long ulCount)
[
   //
   // Loop while there are more characters to send.
   //
   while(ulCount--)
   [
       //
       // Write the next character to the UART.
       //
       ROM_UARTCharPutNonBlocking(UART3_BASE, *pucBuffer++);
   ]
]
//*****************************************************************************
//
// This example demonstrates how to send a string of data to the UART.
//
//*****************************************************************************
int
main(void)
[
   tRectangle sRect;
   tContext sContext;
   //
   // The FPU should be enabled because some compilers will use floating-
   // point registers, even for non-floating-point code.  If the FPU is not
   // enabled this will cause a fault.  This also ensures that floating-
   // point operations could be added to this application and would work
   // correctly and use the hardware floating-point unit.  Finally, lazy
   // stacking is enabled for interrupt handlers.  This allows floating-
   // point instructions to be used within interrupt handlers, but at the
   // expense of extra stack usage.
   //
   FPUEnable();
   FPULazyStackingEnable();
   //
   // Set the clocking to run directly from the crystal.
   //
   ROM_SysCtlClockSet(SYSCTL_SYSDIV_1 | SYSCTL_USE_OSC | SYSCTL_OSC_MAIN |
                      SYSCTL_XTAL_16MHZ);
   //
   // Initialize the display driver.
   //
   CFAL96x64x16Init();
   //
   // Initialize the graphics context.
   //
   GrContextInit(&sContext, &g_sCFAL96x64x16);
   //
   // Fill the top part of the screen with blue to create the banner.
   //
   sRect.sXMin = 0;
   sRect.sYMin = 0;
   sRect.sXMax = GrContextDpyWidthGet(&sContext) - 1;
   sRect.sYMax = 9;
   GrContextForegroundSet(&sContext, ClrDarkBlue);
   GrRectFill(&sContext, &sRect);
   //
   // Change foreground for white text.
   //
   GrContextForegroundSet(&sContext, ClrWhite);
   //
   // Put the application name in the middle of the banner.
   //
   GrContextFontSet(&sContext, g_pFontFixed6x8);
   GrStringDrawCentered(&sContext, "OURS-uart3-echo", -1,
                        GrContextDpyWidthGet(&sContext) / 2, 4, 0);
   //
   // Initialize the display and write some instructions.
   //
   GrStringDrawCentered(&sContext, "Connect a", -1,
                        GrContextDpyWidthGet(&sContext) / 2, 20, false);
   GrStringDrawCentered(&sContext, "terminal", -1,
                        GrContextDpyWidthGet(&sContext) / 2, 30, false);
   GrStringDrawCentered(&sContext, "to UART3.", -1,
                        GrContextDpyWidthGet(&sContext) / 2, 40, false);
   GrStringDrawCentered(&sContext, "115200,N,8,1", -1,
                        GrContextDpyWidthGet(&sContext) / 2, 50, false);
   //
   // Enable the peripherals used by this example.
   //
   ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
   ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART3);
   //
   // Enable processor interrupts.
   //
   ROM_IntMasterEnable();
   //
   // Set GPIO G4 and G5 as UART pins.
   //
   ROM_GPIOPinTypeUART(GPIO_PORTC_BASE, GPIO_PIN_6 | GPIO_PIN_7);
   //
   // Configure the UART for 115,200, 8-N-1 operation.
   //
   ROM_UARTConfigSetExpClk(UART3_BASE, ROM_SysCtlClockGet(), 115200,
                           (UART_CONFIG_WLEN_8 | UART_CONFIG_STOP_ONE |
                            UART_CONFIG_PAR_NONE));
   //
   // Enable the UART interrupt.
   //
   ROM_IntEnable(INT_UART3);
   ROM_UARTIntEnable(UART3_BASE, UART_INT_RX | UART_INT_RT);
   //
   // Prompt for text to be entered.
   //
   UARTSend((unsigned char *)"Please Enter: ", 16);
   //
   // Loop forever echoing data through the UART.
   //
   while(1)
   [
   ]
]

能进得了中断吗？ 建议你看看寄存器对比下器件手册，看看UART3是否在正常工作

    因为UART0的引脚是默认 UART0模式，但是其他的UART单元所使用的引脚需要通过硬件配置下才能使用。可以添加以下两行代码试下：          
   GPIOPinConfigure(GPIO_PC4_U1RX);    
         GPIOPinConfigure(GPIO_PC5_U1TX);

PC6和PC7管脚是复用的，所以你需要配置GPIO pin脚的功能

                        GPIOPinConfigure(GPIO_PC6_U3RX);
                        GPIOPinConfigure(GPIO_PC7_U3TX);

好的，我试试去，谢谢！

   ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOC);
   GPIOPinConfigure(GPIO_PC6_U3RX);
   GPIOPinConfigure(GPIO_PC7_U3TX);
   ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UART3);
按照您的方法配置了，现在是目标板能发送信号，但接收不了（即：在目标板上复位时，在PC机的串口调试工具里能显示："please enter:"，但PC机端的串口调试工具里点击发送却没有任何反应）

检查一下Startup.c文件中
串口3的中断函数有没有正确注册！怀疑是这个问题！！
或者你在中断函数中设置断点，看看PC上发送文字能否进中断处理函数。

OK，太好了，非常感谢您的支持！

我配置了pin脚还是无法通信，板子reset调试工具什么都无法显示，相同代码配置uart0可以显示。我的代码如下：
int main(void)
[
char cThisChar;
//SysCtlClockSet(SYSCTL_SYSDIV_4|SYSCTL_USE_PLL|SYSCTL_XTAL_16MHZ|SYSCTL_OSC_MAIN);
SysCtlClockSet(SYSCTL_SYSDIV_1|SYSCTL_USE_OSC|SYSCTL_OSC_MAIN|SYSCTL_XTAL_16MHZ);
SysCtlPeripheralEnable(SYSCTL_PERIPH_UART1);
SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
GPIOPinConfigure(GPIO_PB0_U1RX);
GPIOPinConfigure(GPIO_PB1_U1TX);
GPIOPinTypeUART(GPIO_PORTB_BASE,GPIO_PIN_0|GPIO_PIN_1);
UARTConfigSetExpClk(UART1_BASE,SysCtlClockGet(),115200,(UART_CONFIG_WLEN_8|UART_CONFIG_STOP_ONE|UART_CONFIG_PAR_NONE));

UARTCharPut(UART1_BASE,'!');
do
[
cThisChar=UARTCharGet(UART1_BASE);
UARTCharPut(UART1_BASE,cThisChar);
]while ((cThisChar!='n')&&(cThisChar!='r'));
return(0);
]