コード例 #1
0
ファイル: main.c プロジェクト: joseayebenes/TivaFly
void confSys(){
	//
	// Set the clocking to run at 40 MHz from the PLL.
	//
	ROM_SysCtlClockSet(SYSCTL_SYSDIV_5 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ |
			SYSCTL_OSC_MAIN);	//Ponermos el reloj principal a 40 MHz (200 Mhz del Pll dividido por 5)


	// Get the system clock speed.
	g_ulSystemClock = SysCtlClockGet();


	//Habilita el clock gating de los perifericos durante el bajo consumo --> perifericos que se desee activos en modo Sleep
	//                                                                        deben habilitarse con SysCtlPeripheralSleepEnable
	ROM_SysCtlPeripheralClockGating(true);

	// Inicializa el subsistema de medida del uso de CPU (mide el tiempo que la CPU no esta dormida)
	// Para eso utiliza un timer, que aqui hemos puesto que sea el TIMER3 (ultimo parametro que se pasa a la funcion)
	// (y por tanto este no se deberia utilizar para otra cosa).
	CPUUsageInit(g_ulSystemClock, configTICK_RATE_HZ/10, 3);
}
コード例 #2
0
//*****************************************************************************
//
// This example demonstrates how to use the uDMA controller to transfer data
// between memory buffers and to and from a peripheral, in this case a UART.
// The uDMA controller is configured to repeatedly transfer a block of data
// from one memory buffer to another.  It is also set up to repeatedly copy a
// block of data from a buffer to the UART output.  The UART data is looped
// back so the same data is received, and the uDMA controlled is configured to
// continuously receive the UART data using ping-pong buffers.
//
// The processor is put to sleep when it is not doing anything, and this allows
// collection of CPU usage data to see how much CPU is being used while the
// data transfers are ongoing.
//
//*****************************************************************************
int
main(void)
{
    static unsigned long ulPrevSeconds;
    static unsigned long ulPrevXferCount;
    static unsigned long ulPrevUARTCount = 0;
    static char cStrBuf[40];
    tRectangle sRect;
    unsigned long ulCenterX;
    unsigned long ulXfersCompleted;
    unsigned long ulBytesTransferred;

    //
    // Set the clocking to run from the PLL at 50 MHz.
    //
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

    //
    // Set the device pinout appropriately for this board.
    //
    PinoutSet();

    //
    // Enable peripherals to operate when CPU is in sleep.
    //
    ROM_SysCtlPeripheralClockGating(true);

    //
    // Initialize the display driver.
    //
    Kitronix320x240x16_SSD2119Init();

    //
    // Initialize the graphics context and find the middle X coordinate.
    //
    GrContextInit(&g_sContext, &g_sKitronix320x240x16_SSD2119);

    //
    // Get the center X coordinate of the screen, since it is used a lot.
    //
    ulCenterX = GrContextDpyWidthGet(&g_sContext) / 2;

    //
    // Fill the top 15 rows of the screen with blue to create the banner.
    //
    sRect.sXMin = 0;
    sRect.sYMin = 0;
    sRect.sXMax = GrContextDpyWidthGet(&g_sContext) - 1;
    sRect.sYMax = 23;
    GrContextForegroundSet(&g_sContext, ClrDarkBlue);
    GrRectFill(&g_sContext, &sRect);

    //
    // Put a white box around the banner.
    //
    GrContextForegroundSet(&g_sContext, ClrWhite);
    GrRectDraw(&g_sContext, &sRect);

    //
    // Put the application name in the middle of the banner.
    //
    GrContextFontSet(&g_sContext, g_pFontCm20);
    GrStringDrawCentered(&g_sContext, "udma-demo", -1, ulCenterX, 11, 0);

    //
    // Show the clock frequency on the display.
    //
    GrContextFontSet(&g_sContext, g_pFontCmss18b);
    usnprintf(cStrBuf, sizeof(cStrBuf), "Stellaris @ %u MHz",
              SysCtlClockGet() / 1000000);
    GrStringDrawCentered(&g_sContext, cStrBuf, -1, ulCenterX, 40, 0);

    //
    // Show static text and field labels on the display.
    //
    GrStringDrawCentered(&g_sContext, "uDMA Mem Transfers", -1,
                         ulCenterX, 62, 0);
    GrStringDrawCentered(&g_sContext, "uDMA UART Transfers", -1,
                         ulCenterX, 84, 0);

    //
    // Configure SysTick to occur 100 times per second, to use as a time
    // reference.  Enable SysTick to generate interrupts.
    //
    ROM_SysTickPeriodSet(ROM_SysCtlClockGet() / SYSTICKS_PER_SECOND);
    ROM_SysTickIntEnable();
    ROM_SysTickEnable();

    //
    // Initialize the CPU usage measurement routine.
    //
    CPUUsageInit(SysCtlClockGet(), SYSTICKS_PER_SECOND, 2);

    //
    // Enable the uDMA controller at the system level.  Enable it to continue
    // to run while the processor is in sleep.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
    ROM_SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_UDMA);

    //
    // Enable the uDMA controller error interrupt.  This interrupt will occur
    // if there is a bus error during a transfer.
    //
    ROM_IntEnable(INT_UDMAERR);

    //
    // Enable the uDMA controller.
    //
    ROM_uDMAEnable();

    //
    // Point at the control table to use for channel control structures.
    //
    ROM_uDMAControlBaseSet(ucControlTable);

    //
    // Initialize the uDMA memory to memory transfers.
    //
    InitSWTransfer();

    //
    // Initialize the uDMA UART transfers.
    //
    InitUART0Transfer();

    //
    // Remember the current SysTick seconds count.
    //
    ulPrevSeconds = g_ulSeconds;

    //
    // Remember the current count of memory buffer transfers.
    //
    ulPrevXferCount = g_ulMemXferCount;

    //
    // Loop until the button is pressed.  The processor is put to sleep
    // in this loop so that CPU utilization can be measured.
    //
    while(1)
    {
        //
        // Check to see if one second has elapsed.  If so, the make some
        // updates.
        //
        if(g_ulSeconds != ulPrevSeconds)
        {
            //
            // Print a message to the display showing the CPU usage percent.
            // The fractional part of the percent value is ignored.
            //
            usnprintf(cStrBuf, sizeof(cStrBuf), "CPU utilization %2u%%",
                      g_ulCPUUsage >> 16);
            GrStringDrawCentered(&g_sContext, cStrBuf, -1, ulCenterX, 160, 1);

            //
            // Tell the user how many seconds we have to go before ending.
            //
            usnprintf(cStrBuf, sizeof(cStrBuf), " Test ends in %d seconds ",
                      10 - g_ulSeconds);
            GrStringDrawCentered(&g_sContext, cStrBuf, -1, ulCenterX, 120, 1);

            //
            // Remember the new seconds count.
            //
            ulPrevSeconds = g_ulSeconds;

            //
            // Calculate how many memory transfers have occurred since the last
            // second.
            //
            ulXfersCompleted = g_ulMemXferCount - ulPrevXferCount;

            //
            // Remember the new transfer count.
            //
            ulPrevXferCount = g_ulMemXferCount;

            //
            // Compute how many bytes were transferred in the memory transfer
            // since the last second.
            //
            ulBytesTransferred = ulXfersCompleted * MEM_BUFFER_SIZE * 4;

            //
            // Print a message to the display showing the memory transfer rate.
            //
            usnprintf(cStrBuf, sizeof(cStrBuf), " %8u Bytes/Sec ",
                      ulBytesTransferred);
            GrStringDrawCentered(&g_sContext, cStrBuf, -1, ulCenterX, 182, 1);

            //
            // Calculate how many UART transfers have occurred since the last
            // second.
            //
            ulXfersCompleted = (g_ulRxBufACount + g_ulRxBufBCount -
                                ulPrevUARTCount);

            //
            // Remember the new UART transfer count.
            //
            ulPrevUARTCount = g_ulRxBufACount + g_ulRxBufBCount;

            //
            // Compute how many bytes were transferred by the UART.  The number
            // of bytes received is multiplied by 2 so that the TX bytes
            // transferred are also accounted for.
            //
            ulBytesTransferred = ulXfersCompleted * UART_RXBUF_SIZE * 2;

            //
            // Print a message to the display showing the UART transfer rate.
            //
            usnprintf(cStrBuf, sizeof(cStrBuf), " %8u Bytes/Sec ",
                      ulBytesTransferred);
            GrStringDrawCentered(&g_sContext, cStrBuf, -1, ulCenterX, 204, 1);
        }

        //
        // Put the processor to sleep if there is nothing to do.  This allows
        // the CPU usage routine to measure the number of free CPU cycles.
        // If the processor is sleeping a lot, it can be hard to connect to
        // the target with the debugger.
        //
        SysCtlSleep();

        //
        // See if we have run long enough and exit the loop if so.
        //
        if(g_ulSeconds >= 10)
        {
            break;
        }
    }
コード例 #3
0
//*****************************************************************************
//
// This example demonstrates how to use the uDMA controller to transfer data
// between memory buffers and to and from a peripheral, in this case a UART.
// The uDMA controller is configured to repeatedly transfer a block of data
// from one memory buffer to another.  It is also set up to repeatedly copy a
// block of data from a buffer to the UART output.  The UART data is looped
// back so the same data is received, and the uDMA controlled is configured to
// continuously receive the UART data using ping-pong buffers.
//
// The processor is put to sleep when it is not doing anything, and this allows
// collection of CPU usage data to see how much CPU is being used while the
// data transfers are ongoing.
//
//*****************************************************************************
int
main(void)
{
    static uint32_t ui32PrevSeconds;
    static uint32_t ui32PrevXferCount;
    static uint32_t ui32PrevUARTCount = 0;
    uint32_t ui32XfersCompleted;
    uint32_t ui32BytesTransferred;

    //
    // Enable lazy stacking for interrupt handlers.  This allows floating-point
    // instructions to be used within interrupt handlers, but at the expense of
    // extra stack usage.
    //
    ROM_FPULazyStackingEnable();

    //
    // Set the clocking to run from the PLL at 50 MHz.
    //
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

    //
    // Enable peripherals to operate when CPU is in sleep.
    //
    ROM_SysCtlPeripheralClockGating(true);

    //
    // Enable the GPIO port that is used for the on-board LED.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOF);

    //
    // Enable the GPIO pins for the LED (PF2).
    //
    ROM_GPIOPinTypeGPIOOutput(GPIO_PORTF_BASE, GPIO_PIN_2);

    //
    // Initialize the UART.
    //
    ConfigureUART();

    UARTprintf("\033[2JuDMA Example\n");

    //
    // Show the clock frequency on the display.
    //
    UARTprintf("Tiva C Series @ %u MHz\n\n", ROM_SysCtlClockGet() / 1000000);

    //
    // Show statistics headings.
    //
    UARTprintf("CPU    Memory     UART       Remaining\n");
    UARTprintf("Usage  Transfers  Transfers  Time\n");

    //
    // Configure SysTick to occur 100 times per second, to use as a time
    // reference.  Enable SysTick to generate interrupts.
    //
    ROM_SysTickPeriodSet(ROM_SysCtlClockGet() / SYSTICKS_PER_SECOND);
    ROM_SysTickIntEnable();
    ROM_SysTickEnable();

    //
    // Initialize the CPU usage measurement routine.
    //
    CPUUsageInit(ROM_SysCtlClockGet(), SYSTICKS_PER_SECOND, 2);

    //
    // Enable the uDMA controller at the system level.  Enable it to continue
    // to run while the processor is in sleep.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
    ROM_SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_UDMA);

    //
    // Enable the uDMA controller error interrupt.  This interrupt will occur
    // if there is a bus error during a transfer.
    //
    ROM_IntEnable(INT_UDMAERR);

    //
    // Enable the uDMA controller.
    //
    ROM_uDMAEnable();

    //
    // Point at the control table to use for channel control structures.
    //
    ROM_uDMAControlBaseSet(ui8ControlTable);

    //
    // Initialize the uDMA memory to memory transfers.
    //
    InitSWTransfer();

    //
    // Initialize the uDMA UART transfers.
    //
    InitUART1Transfer();

    //
    // Remember the current SysTick seconds count.
    //
    ui32PrevSeconds = g_ui32Seconds;

    //
    // Remember the current count of memory buffer transfers.
    //
    ui32PrevXferCount = g_ui32MemXferCount;

    //
    // Loop until the button is pressed.  The processor is put to sleep
    // in this loop so that CPU utilization can be measured.
    //
    while(1)
    {
        //
        // Check to see if one second has elapsed.  If so, the make some
        // updates.
        //
        if(g_ui32Seconds != ui32PrevSeconds)
        {
            //
            // Turn on the LED as a heartbeat
            //
            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, GPIO_PIN_2);

            //
            // Print a message to the display showing the CPU usage percent.
            // The fractional part of the percent value is ignored.
            //
            UARTprintf("\r%3d%%   ", g_ui32CPUUsage >> 16);

            //
            // Remember the new seconds count.
            //
            ui32PrevSeconds = g_ui32Seconds;

            //
            // Calculate how many memory transfers have occurred since the last
            // second.
            //
            ui32XfersCompleted = g_ui32MemXferCount - ui32PrevXferCount;

            //
            // Remember the new transfer count.
            //
            ui32PrevXferCount = g_ui32MemXferCount;

            //
            // Compute how many bytes were transferred in the memory transfer
            // since the last second.
            //
            ui32BytesTransferred = ui32XfersCompleted * MEM_BUFFER_SIZE * 4;

            //
            // Print a message showing the memory transfer rate.
            //
            if(ui32BytesTransferred >= 100000000)
            {
                UARTprintf("%3d MB/s   ", ui32BytesTransferred / 1000000);
            }
            else if(ui32BytesTransferred >= 10000000)
            {
                UARTprintf("%2d.%01d MB/s  ", ui32BytesTransferred / 1000000,
                           (ui32BytesTransferred % 1000000) / 100000);
            }
            else if(ui32BytesTransferred >= 1000000)
            {
                UARTprintf("%1d.%02d MB/s  ", ui32BytesTransferred / 1000000,
                           (ui32BytesTransferred % 1000000) / 10000);
            }
            else if(ui32BytesTransferred >= 100000)
            {
                UARTprintf("%3d KB/s   ", ui32BytesTransferred / 1000);
            }
            else if(ui32BytesTransferred >= 10000)
            {
                UARTprintf("%2d.%01d KB/s  ", ui32BytesTransferred / 1000,
                           (ui32BytesTransferred % 1000) / 100);
            }
            else if(ui32BytesTransferred >= 1000)
            {
                UARTprintf("%1d.%02d KB/s  ", ui32BytesTransferred / 1000,
                           (ui32BytesTransferred % 1000) / 10);
            }
            else if(ui32BytesTransferred >= 100)
            {
                UARTprintf("%3d B/s    ", ui32BytesTransferred);
            }
            else if(ui32BytesTransferred >= 10)
            {
                UARTprintf("%2d B/s     ", ui32BytesTransferred);
            }
            else
            {
                UARTprintf("%1d B/s      ", ui32BytesTransferred);
            }

            //
            // Calculate how many UART transfers have occurred since the last
            // second.
            //
            ui32XfersCompleted = (g_ui32RxBufACount + g_ui32RxBufBCount -
                                  ui32PrevUARTCount);

            //
            // Remember the new UART transfer count.
            //
            ui32PrevUARTCount = g_ui32RxBufACount + g_ui32RxBufBCount;

            //
            // Compute how many bytes were transferred by the UART.  The number
            // of bytes received is multiplied by 2 so that the TX bytes
            // transferred are also accounted for.
            //
            ui32BytesTransferred = ui32XfersCompleted * UART_RXBUF_SIZE * 2;

            //
            // Print a message showing the UART transfer rate.
            //
            if(ui32BytesTransferred >= 1000000)
            {
                UARTprintf("%1d.%02d MB/s  ", ui32BytesTransferred / 1000000,
                           (ui32BytesTransferred % 1000000) / 10000);
            }
            else if(ui32BytesTransferred >= 100000)
            {
                UARTprintf("%3d KB/s   ", ui32BytesTransferred / 1000);
            }
            else if(ui32BytesTransferred >= 10000)
            {
                UARTprintf("%2d.%01d KB/s  ", ui32BytesTransferred / 1000,
                           (ui32BytesTransferred % 1000) / 100);
            }
            else if(ui32BytesTransferred >= 1000)
            {
                UARTprintf("%1d.%02d KB/s  ", ui32BytesTransferred / 1000,
                           (ui32BytesTransferred % 1000) / 10);
            }
            else if(ui32BytesTransferred >= 100)
            {
                UARTprintf("%3d B/s    ", ui32BytesTransferred);
            }
            else if(ui32BytesTransferred >= 10)
            {
                UARTprintf("%2d B/s     ", ui32BytesTransferred);
            }
            else
            {
                UARTprintf("%1d B/s      ", ui32BytesTransferred);
            }

            //
            // Print a spinning line to make it more apparent that there is
            // something happening.
            //
            UARTprintf("%2ds", 10 - ui32PrevSeconds);

            //
            // Turn off the LED.
            //
            GPIOPinWrite(GPIO_PORTF_BASE, GPIO_PIN_2, 0);
        }

        //
        // Put the processor to sleep if there is nothing to do.  This allows
        // the CPU usage routine to measure the number of free CPU cycles.
        // If the processor is sleeping a lot, it can be hard to connect to
        // the target with the debugger.
        //
        ROM_SysCtlSleep();

        //
        // See if we have run int32_t enough and exit the loop if so.
        //
        if(g_ui32Seconds >= 10)
        {
            break;
        }
    }
コード例 #4
0
ファイル: ui.c プロジェクト: VENGEL/StellarisWare
//*****************************************************************************
//
//! Initializes the user interface.
//!
//! This function initializes the user interface modules (on-board and serial),
//! preparing them to operate and control the motor drive.
//!
//! \return None.
//
//*****************************************************************************
void
UIInit(void)
{
    unsigned long ulSysTickVal;

    //
    // Enable the GPIO peripherals needed for the button and LEDs
    //
    SysCtlPeripheralEnable(USER_BUTTON_GPIO_PERIPH);
    SysCtlPeripheralEnable(LED_GPIO_PERIPH);

    //
    // Set up button GPIO as input, and LEDs as outputs, and turn them off
    //
    GPIODirModeSet(USER_BUTTON_PORT, USER_BUTTON_PIN, GPIO_DIR_MODE_IN);
    GPIODirModeSet(STATUS_LED_PORT, STATUS_LED_PIN, GPIO_DIR_MODE_OUT);
    GPIODirModeSet(MODE_LED_PORT, MODE_LED_PIN, GPIO_DIR_MODE_OUT);
    GPIOPinWrite(STATUS_LED_PORT, STATUS_LED_PIN, 0);
    GPIOPinWrite(MODE_LED_PORT, MODE_LED_PIN, 0);

    //
    // Set up the LED blinking function
    //
    BlinkInit(STATUS_LED, STATUS_LED_PORT, STATUS_LED_PIN);
    BlinkInit(MODE_LED, MODE_LED_PORT, MODE_LED_PIN);
    BlinkStart(MODE_LED, UI_INT_RATE / 2, UI_INT_RATE / 2, eUIMode + 1);

    //
    // Enable the ADC peripheral, needed for potentiometer
    //
    SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);
    SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_ADC0);

    //
    // Set the ADC to run at the maximum rate of 500 ksamples.
    //
    HWREG(SYSCTL_RCGC0) |= 0x00000200;
    HWREG(SYSCTL_SCGC0) |= 0x00000200;

    //
    // Program sequencer for collecting ADC sample for potentiometer
    // position, bus voltage, and temperature sensor.
    //
    ADCSequenceConfigure(ADC0_BASE, UI_ADC_SEQUENCER, ADC_TRIGGER_PROCESSOR,
                         UI_ADC_PRIORITY);
    ADCSequenceStepConfigure(ADC0_BASE, UI_ADC_SEQUENCER, 0, POT_ADC_CHAN);
    ADCSequenceStepConfigure(ADC0_BASE, UI_ADC_SEQUENCER, 1, BUSV_ADC_CHAN);
    ADCSequenceStepConfigure(ADC0_BASE, UI_ADC_SEQUENCER, 2,
                             ADC_CTL_TS | ADC_CTL_END);
    ADCSequenceEnable(ADC0_BASE, UI_ADC_SEQUENCER);
    ADCProcessorTrigger(ADC0_BASE, UI_ADC_SEQUENCER);   // take initial sample

    //
    // initialize the lower level,
    // positioner, which handles computing all the motion control
    //
    StepperInit();

    //
    // Get a pointer to the stepper status.
    //
    pStepperStatus = StepperGetMotorStatus();

    //
    // Force an update of all the parameters (sets defaults).
    //
    UISetPWMFreq();
    UISetChopperBlanking();
    UISetMotorParms();
    UISetControlMode();
    UISetDecayMode();
    UISetStepMode();
    UISetFixedOnTime();

    //
    // Initialize the flash parameter block driver.
    //
    FlashPBInit(FLASH_PB_START, FLASH_PB_END, FLASH_PB_SIZE);

    //
    // Initialize the serial user interface.
    //
    UISerialInit();
    IntPrioritySet(INT_UART0, UI_SER_INT_PRI);

    //
    // Make sure that the UART doesnt get put to sleep
    //
    SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_UART0);

    //
    // Initialize the on-board user interface.
    //
    UIOnboardInit(GPIOPinRead(USER_BUTTON_PORT, USER_BUTTON_PIN), 0);

    //
    // Initialize the processor usage routine.
    //
    CPUUsageInit(SysCtlClockGet(), UI_INT_RATE, 2);

    //
    // Configure SysTick to provide a periodic user interface interrupt.
    //
    SysTickPeriodSet(SysCtlClockGet() / UI_INT_RATE);
    SysTickIntEnable();
    SysTickEnable();
    IntPrioritySet(FAULT_SYSTICK, SYSTICK_INT_PRI);

    //
    // A delay is needed to let the current sense line discharge after
    // reset, before the current fault parameter is configured.  The
    // two loops below let the systick roll around once before proceeding.
    //
    ulSysTickVal = SysTickValueGet();

    //
    // Wait for systick to reach 0 and roll over to top.
    //
    while(SysTickValueGet() <= ulSysTickVal)
    {
    }

    //
    // Wait for systick to get back to the starting value.
    //
    while(SysTickValueGet() > ulSysTickVal)
    {
    }

    //
    // Now set the current fault parameter (after the delay above).
    //
    UISetFaultParms();

    //
    // Load stored parameters from flash, if any are available.
    //
    UIParamLoad();
}
コード例 #5
0
//*****************************************************************************
//
// This example demonstrates how to use the uDMA controller to transfer data
// between memory buffers and to and from a peripheral, in this case a UART.
// The uDMA controller is configured to repeatedly transfer a block of data
// from one memory buffer to another.  It is also set up to repeatedly copy a
// block of data from a buffer to the UART output.  The UART data is looped
// back so the same data is received, and the uDMA controlled is configured to
// continuously receive the UART data using ping-pong buffers.
//
// The processor is put to sleep when it is not doing anything, and this allows
// collection of CPU usage data to see how much CPU is being used while the
// data transfers are ongoing.
//
//*****************************************************************************
int
main(void)
{
    static unsigned long ulPrevSeconds;
    static unsigned long ulPrevXferCount;
    static unsigned long ulPrevUARTCount = 0;
    unsigned long ulXfersCompleted;
    unsigned long ulBytesTransferred;
    unsigned long ulButton;

    //
    // Set the clocking to run from the PLL at 50 MHz.
    //
    ROM_SysCtlClockSet(SYSCTL_SYSDIV_4 | SYSCTL_USE_PLL | SYSCTL_OSC_MAIN |
                       SYSCTL_XTAL_16MHZ);

    //
    // Enable peripherals to operate when CPU is in sleep.
    //
    ROM_SysCtlPeripheralClockGating(true);

    //
    // Set the push button as an input with a pull-up.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOB);
    ROM_GPIODirModeSet(GPIO_PORTB_BASE, GPIO_PIN_4, GPIO_DIR_MODE_IN);
    ROM_GPIOPadConfigSet(GPIO_PORTB_BASE, GPIO_PIN_4,
                         GPIO_STRENGTH_2MA, GPIO_PIN_TYPE_STD_WPU);

    //
    // Initialize the UART.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOA);
    ROM_SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_UART0);
    GPIOPinConfigure(GPIO_PA0_U0RX);
    GPIOPinConfigure(GPIO_PA1_U0TX);
    ROM_GPIOPinTypeUART(GPIO_PORTA_BASE, GPIO_PIN_0 | GPIO_PIN_1);
    UARTStdioInit(0);
    UARTprintf("\033[2JuDMA Example\n");

    //
    // Show the clock frequency and exit instructions.
    //
    UARTprintf("Stellaris @ %u MHz\n", ROM_SysCtlClockGet() / 1000000);
    UARTprintf("Press button to use debugger.\n\n");

    //
    // Show statistics headings.
    //
    UARTprintf("CPU    Memory     UART\n");
    UARTprintf("Usage  Transfers  Transfers\n");

    //
    // Configure SysTick to occur 100 times per second, to use as a time
    // reference.  Enable SysTick to generate interrupts.
    //
    ROM_SysTickPeriodSet(ROM_SysCtlClockGet() / SYSTICKS_PER_SECOND);
    ROM_SysTickIntEnable();
    ROM_SysTickEnable();

    //
    // Initialize the CPU usage measurement routine.
    //
    CPUUsageInit(ROM_SysCtlClockGet(), SYSTICKS_PER_SECOND, 2);

    //
    // Enable the uDMA controller at the system level.  Enable it to continue
    // to run while the processor is in sleep.
    //
    ROM_SysCtlPeripheralEnable(SYSCTL_PERIPH_UDMA);
    ROM_SysCtlPeripheralSleepEnable(SYSCTL_PERIPH_UDMA);

    //
    // Enable the uDMA controller error interrupt.  This interrupt will occur
    // if there is a bus error during a transfer.
    //
    ROM_IntEnable(INT_UDMAERR);

    //
    // Enable the uDMA controller.
    //
    ROM_uDMAEnable();

    //
    // Point at the control table to use for channel control structures.
    //
    ROM_uDMAControlBaseSet(ucControlTable);

    //
    // Initialize the uDMA memory to memory transfers.
    //
    InitSWTransfer();

    //
    // Initialize the uDMA UART transfers.
    //
    InitUART1Transfer();

    //
    // Remember the current SysTick seconds count.
    //
    ulPrevSeconds = g_ulSeconds;

    //
    // Remember the current count of memory buffer transfers.
    //
    ulPrevXferCount = g_ulMemXferCount;

    //
    // Loop until the button is pressed.  The processor is put to sleep
    // in this loop so that CPU utilization can be measured.  When the
    // processor is sleeping a lot, it can be hard to connect to the target
    // with the debugger.  Pressing the button will cause this loop to exit
    // and the processor will no longer sleep.
    //
    while(1)
    {
        //
        // Check for the select button press.  If the button is pressed,
        // then exit this loop.
        //
        ulButton = ROM_GPIOPinRead(GPIO_PORTB_BASE, GPIO_PIN_4);
        if(!ulButton)
        {
            break;
        }

        //
        // Check to see if one second has elapsed.  If so, the make some
        // updates.
        //
        if(g_ulSeconds != ulPrevSeconds)
        {
            //
            // Print a message to the display showing the CPU usage percent.
            // The fractional part of the percent value is ignored.
            //
            UARTprintf("\r%3d%%   ", g_ulCPUUsage >> 16);

            //
            // Remember the new seconds count.
            //
            ulPrevSeconds = g_ulSeconds;

            //
            // Calculate how many memory transfers have occurred since the last
            // second.
            //
            ulXfersCompleted = g_ulMemXferCount - ulPrevXferCount;

            //
            // Remember the new transfer count.
            //
            ulPrevXferCount = g_ulMemXferCount;

            //
            // Compute how many bytes were transferred in the memory transfer
            // since the last second.
            //
            ulBytesTransferred = ulXfersCompleted * MEM_BUFFER_SIZE * 4;

            //
            // Print a message showing the memory transfer rate.
            //
            if(ulBytesTransferred >= 100000000)
            {
                UARTprintf("%3d MB/s   ", ulBytesTransferred / 1000000);
            }
            else if(ulBytesTransferred >= 10000000)
            {
                UARTprintf("%2d.%01d MB/s  ", ulBytesTransferred / 1000000,
                           (ulBytesTransferred % 1000000) / 100000);
            }
            else if(ulBytesTransferred >= 1000000)
            {
                UARTprintf("%1d.%02d MB/s  ", ulBytesTransferred / 1000000,
                           (ulBytesTransferred % 1000000) / 10000);
            }
            else if(ulBytesTransferred >= 100000)
            {
                UARTprintf("%3d KB/s   ", ulBytesTransferred / 1000);
            }
            else if(ulBytesTransferred >= 10000)
            {
                UARTprintf("%2d.%01d KB/s  ", ulBytesTransferred / 1000,
                           (ulBytesTransferred % 1000) / 100);
            }
            else if(ulBytesTransferred >= 1000)
            {
                UARTprintf("%1d.%02d KB/s  ", ulBytesTransferred / 1000,
                           (ulBytesTransferred % 1000) / 10);
            }
            else if(ulBytesTransferred >= 100)
            {
                UARTprintf("%3d B/s    ", ulBytesTransferred);
            }
            else if(ulBytesTransferred >= 10)
            {
                UARTprintf("%2d B/s     ", ulBytesTransferred);
            }
            else
            {
                UARTprintf("%1d B/s      ", ulBytesTransferred);
            }

            //
            // Calculate how many UART transfers have occurred since the last
            // second.
            //
            ulXfersCompleted = (g_ulRxBufACount + g_ulRxBufBCount -
                                ulPrevUARTCount);

            //
            // Remember the new UART transfer count.
            //
            ulPrevUARTCount = g_ulRxBufACount + g_ulRxBufBCount;

            //
            // Compute how many bytes were transferred by the UART.  The number
            // of bytes received is multiplied by 2 so that the TX bytes
            // transferred are also accounted for.
            //
            ulBytesTransferred = ulXfersCompleted * UART_RXBUF_SIZE * 2;

            //
            // Print a message showing the UART transfer rate.
            //
            if(ulBytesTransferred >= 1000000)
            {
                UARTprintf("%1d.%02d MB/s  ", ulBytesTransferred / 1000000,
                           (ulBytesTransferred % 1000000) / 10000);
            }
            else if(ulBytesTransferred >= 100000)
            {
                UARTprintf("%3d KB/s   ", ulBytesTransferred / 1000);
            }
            else if(ulBytesTransferred >= 10000)
            {
                UARTprintf("%2d.%01d KB/s  ", ulBytesTransferred / 1000,
                           (ulBytesTransferred % 1000) / 100);
            }
            else if(ulBytesTransferred >= 1000)
            {
                UARTprintf("%1d.%02d KB/s  ", ulBytesTransferred / 1000,
                           (ulBytesTransferred % 1000) / 10);
            }
            else if(ulBytesTransferred >= 100)
            {
                UARTprintf("%3d B/s    ", ulBytesTransferred);
            }
            else if(ulBytesTransferred >= 10)
            {
                UARTprintf("%2d B/s     ", ulBytesTransferred);
            }
            else
            {
                UARTprintf("%1d B/s      ", ulBytesTransferred);
            }

            //
            // Print a spinning line to make it more apparent that there is
            // something happening.
            //
            UARTprintf("%c", g_pcTwirl[ulPrevSeconds % 4]);
        }

        //
        // Put the processor to sleep if there is nothing to do.  This allows
        // the CPU usage routine to measure the number of free CPU cycles.
        // If the processor is sleeping a lot, it can be hard to connect to
        // the target with the debugger.
        //
        ROM_SysCtlSleep();
    }