path: root/usb-device-cdc-serial-project/main.c

/* ----------------------------------------------------------------------------
 *         ATMEL Microcontroller Software Support 
 * ----------------------------------------------------------------------------
 * Copyright (c) 2008, Atmel Corporation
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the disclaimer below.
 *
 * Atmel's name may not be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
 * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
 * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
 * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * ----------------------------------------------------------------------------
 */

//-----------------------------------------------------------------------------
/// \dir "USB CDC serial converter"
///
/// !!!Purpose
///
/// The USB CDC Serial Project will help you to get familiar with the
/// USB Device Port(UDP) and USART interface on AT91SAM microcontrollers. Also
/// it can help you to be familiar with the USB Framework that is used for
/// rapid development of USB-compliant class drivers such as USB Communication
/// Device class (CDC).
///
/// You can find following information depends on your needs:
/// - Sample usage of USB CDC driver and USART driver.
/// - USB CDC driver development based on the AT91 USB Framework.
/// - USB enumerate sequence, the standard and class-specific descriptors and
///   requests handling.
/// - The initialize sequence and usage of UDP interface.
/// - The initialize sequence and usage of USART interface with PDC.
///
/// !See
/// - usart: USART interface driver
/// - tc: TIMER/COUNTER interface driver
/// - usb: USB Framework, USB CDC driver and UDP interface driver
///    - "AT91 USB device framework"
///       - "USBD API"
///    - "cdc-serial"
///       - "USB CDC Serial Device"
///       - "USB CDC Serial Host Driver"
///
/// !!!Requirements
///
/// This package can be used with all Atmel evaluation kits that have both
/// UDP and USART interface.
///
/// The current supported board list:
/// - at91sam7s-ek (exclude at91sam7s32)
/// - at91sam7x-ek
/// - at91sam7xc-ek
/// - at91sam7a3-ek
/// - at91sam7se-ek
/// - at91sam9260-ek
/// - at91sam9263-ek
///
/// !!!Description
///
/// When an EK running this program connected to a host (PC for example), with
/// USB cable, the EK appears as a Seriao COM port for the host, after driver
/// installation with the offered 6119.inf. Then the host can send or receive
/// data through the port with host software. The data stream from the host is
/// then sent to the EK, and forward to USART port of AT91SAM chips. The USART
/// port of the EK is monitored by the timer and the incoming data will be sent
/// to the host.
///
/// !!!Usage
///
/// -# Build the program and download it inside the evaluation board. Please
///    refer to the
///    <a href="http://www.atmel.com/dyn/resources/prod_documents/doc6224.pdf">
///    SAM-BA User Guide</a>, the
///    <a href="http://www.atmel.com/dyn/resources/prod_documents/doc6310.pdf">
///    GNU-Based Software Development</a> application note or to the
///    <a href="ftp://ftp.iar.se/WWWfiles/arm/Guides/EWARM_UserGuide.ENU.pdf">
///    IAR EWARM User Guide</a>, depending on your chosen solution.
/// -# On the computer, open and configure a terminal application
///    (e.g. HyperTerminal on Microsoft Windows) with these settings:
///   - 115200 bauds
///   - 8 bits of data
///   - No parity
///   - 1 stop bit
///   - No flow control
/// -# Start the application.
/// -# In the terminal window, the following text should appear:
///     \code
///     -- USB Device CDC Serial Project xxx --
///     -- AT91xxxxxx-xx
///     -- Compiled: xxx xx xxxx xx:xx:xx --
///     \endcode
/// -# When connecting USB cable to windows, the LED blinks, and the host
///    reports a new USB %device attachment (if it's the first time you connect
///    an %audio speaker demo board to your host). You can use the inf file
///    at91lib\\usb\\device\\cdc-serial\\drv\\6119.inf to install the serial
///    port. Then new "AT91 USB to Serial Converter (COMx)" appears in the
///    hardware %device list.
/// -# You can run hyperterminal to send data to the port. And it can be seen
///    at the other hyperterminal connected to the USART port of the EK.
///
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
/// \unit
///
/// !Purpose
///
/// This file contains all the specific code for the
/// usb-device-cdc-serial-project
///
/// !Contents
///
/// The code can be roughly broken down as follows:
///    - Configuration functions
///       - VBus_Configure
///       - PIO & Timer configurations in start of main
///    - Interrupt handlers
///       - ISR_Vbus
///       - ISR_Timer0
///       - ISR_Usart0
///    - Callback functions
///       - UsbDataReceived
///    - The main function, which implements the program behavior
///
/// Please refer to the list of functions in the #Overview# tab of this unit
/// for more detailed information.
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
//         Headers
//------------------------------------------------------------------------------

#include <board.h>
#include <pio/pio.h>
#include <pio/pio_it.h>
#include <aic/aic.h>
#include <tc/tc.h>
#include <usart/usart.h>
#include <utility/trace.h>
#include <utility/led.h>
#include <usb/device/cdc-serial/CDCDSerialDriver.h>
#include <usb/device/cdc-serial/CDCDSerialDriverDescriptors.h>
#include <pmc/pmc.h>

//------------------------------------------------------------------------------
//      Definitions
//------------------------------------------------------------------------------
#ifndef AT91C_ID_TC0
    #define AT91C_ID_TC0 AT91C_ID_TC
#endif

/// Size in bytes of the buffer used for reading data from the USB & USART
#define DATABUFFERSIZE \
    BOARD_USB_ENDPOINTS_MAXPACKETSIZE(CDCDSerialDriverDescriptors_DATAIN)

/// Use for power management
#define STATE_IDLE    0
/// The USB device is in suspend state
#define STATE_SUSPEND 4
/// The USB device is in resume state
#define STATE_RESUME  5

//------------------------------------------------------------------------------
//      Internal variables
//------------------------------------------------------------------------------
/// State of USB, for suspend and resume
unsigned char USBState = STATE_IDLE;

/// List of pins that must be configured for use by the application.
static const Pin pins[] = {PIN_USART0_TXD, PIN_USART0_RXD};

/// Double-buffer for storing incoming USART data.
static unsigned char usartBuffers[2][DATABUFFERSIZE];

/// Current USART buffer index.
static unsigned char usartCurrentBuffer = 0;

/// Buffer for storing incoming USB data.
static unsigned char usbBuffer[DATABUFFERSIZE];

//------------------------------------------------------------------------------
//         VBus monitoring (optional)
//------------------------------------------------------------------------------
#if defined(PIN_USB_VBUS)

#define VBUS_CONFIGURE()  VBus_Configure()

/// VBus pin instance.
static const Pin pinVbus = PIN_USB_VBUS;

//------------------------------------------------------------------------------
/// Handles interrupts coming from PIO controllers.
//------------------------------------------------------------------------------
static void ISR_Vbus(const Pin *pPin)
{
    // Check current level on VBus
    if (PIO_Get(&pinVbus)) {

        TRACE_INFO("VBUS conn\n\r");
        USBD_Connect();
    }
    else {

        TRACE_INFO("VBUS discon\n\r");
        USBD_Disconnect();
    }
}

//------------------------------------------------------------------------------
/// Configures the VBus pin to trigger an interrupt when the level on that pin
/// changes.
//------------------------------------------------------------------------------
static void VBus_Configure( void )
{
    TRACE_INFO("VBus configuration\n\r");

    // Configure PIO
    PIO_Configure(&pinVbus, 1);
    PIO_ConfigureIt(&pinVbus, ISR_Vbus);
    PIO_EnableIt(&pinVbus);

    // Check current level on VBus
    if (PIO_Get(&pinVbus)) {

        // if VBUS present, force the connect
        TRACE_INFO("VBUS conn\n\r");
        USBD_Connect();
    }
    else {
        USBD_Disconnect();
    }           
}

#else
    #define VBUS_CONFIGURE()    USBD_Connect()
#endif //#if defined(PIN_USB_VBUS)

#if defined (CP15_PRESENT)
//------------------------------------------------------------------------------
/// Put the CPU in 32kHz, disable PLL, main oscillator
/// Put voltage regulator in standby mode
//------------------------------------------------------------------------------
void LowPowerMode(void)
{
    PMC_CPUInIdleMode();
}
//------------------------------------------------------------------------------
/// Put voltage regulator in normal mode
/// Return the CPU to normal speed 48MHz, enable PLL, main oscillator
//------------------------------------------------------------------------------
void NormalPowerMode(void)
{
}

#elif defined(at91sam7a3)
//------------------------------------------------------------------------------
/// Put the CPU in 32kHz, disable PLL, main oscillator
//------------------------------------------------------------------------------
void LowPowerMode(void)
{
    // MCK=48MHz to MCK=32kHz
    // MCK = SLCK/2 : change source first from 48 000 000 to 18. / 2 = 9M
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=SLCK : then change prescaler
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_CSS_SLOW_CLK;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // disable PLL
    AT91C_BASE_PMC->PMC_PLLR = 0;
    // Disable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = 0;

    PMC_DisableProcessorClock();
}
//------------------------------------------------------------------------------
/// Return the CPU to normal speed 48MHz, enable PLL, main oscillator
//------------------------------------------------------------------------------
void NormalPowerMode(void)
{
    // MCK=32kHz to MCK=48MHz
    // enable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = (( (AT91C_CKGR_OSCOUNT & (0x06 <<8)) | AT91C_CKGR_MOSCEN ));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MOSCS ) );

    // enable PLL@96MHz
    AT91C_BASE_PMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x0E) |
         (AT91C_CKGR_PLLCOUNT & (28<<8)) |
         (AT91C_CKGR_MUL & (0x48<<16)));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_LOCK ) );
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1 ;
    // MCK=SLCK/2 : change prescaler first
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=PLLCK/2 : then change source
    AT91C_BASE_PMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK  ;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
}

#elif defined (at91sam7se)
//------------------------------------------------------------------------------
/// Put the CPU in 32kHz, disable PLL, main oscillator
/// Put voltage regulator in standby mode
//------------------------------------------------------------------------------
void LowPowerMode(void)
{
    // MCK=48MHz to MCK=32kHz
    // MCK = SLCK/2 : change source first from 48 000 000 to 18. / 2 = 9M
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=SLCK : then change prescaler
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_CSS_SLOW_CLK;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // disable PLL
    AT91C_BASE_PMC->PMC_PLLR = 0;
    // Disable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = 0;

    // Voltage regulator in standby mode : Enable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR |= AT91C_VREG_PSTDBY;

    PMC_DisableProcessorClock();
}
//------------------------------------------------------------------------------
/// Put voltage regulator in normal mode
/// Return the CPU to normal speed 48MHz, enable PLL, main oscillator
//------------------------------------------------------------------------------
void NormalPowerMode(void)
{
    // Voltage regulator in normal mode : Disable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR &= ~AT91C_VREG_PSTDBY;

    // MCK=32kHz to MCK=48MHz
    // enable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = (( (AT91C_CKGR_OSCOUNT & (0x06 <<8)) | AT91C_CKGR_MOSCEN ));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MOSCS ) );

    // enable PLL@96MHz
    AT91C_BASE_PMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x0E) |
         (AT91C_CKGR_PLLCOUNT & (28<<8)) |
         (AT91C_CKGR_MUL & (0x48<<16)));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_LOCK ) );
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1 ;
    // MCK=SLCK/2 : change prescaler first
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=PLLCK/2 : then change source
    AT91C_BASE_PMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK  ;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
}

#elif defined (at91sam7s)
//------------------------------------------------------------------------------
/// Put the CPU in 32kHz, disable PLL, main oscillator
/// Put voltage regulator in standby mode
//------------------------------------------------------------------------------
void LowPowerMode(void)
{
    // MCK=48MHz to MCK=32kHz
    // MCK = SLCK/2 : change source first from 48 000 000 to 18. / 2 = 9M
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=SLCK : then change prescaler
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_CSS_SLOW_CLK;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // disable PLL
    AT91C_BASE_PMC->PMC_PLLR = 0;
    // Disable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = 0;

    // Voltage regulator in standby mode : Enable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR |= AT91C_VREG_PSTDBY;

    PMC_DisableProcessorClock();
}

//------------------------------------------------------------------------------
/// Put voltage regulator in normal mode
/// Return the CPU to normal speed 48MHz, enable PLL, main oscillator
//------------------------------------------------------------------------------
void NormalPowerMode(void)
{
    // Voltage regulator in normal mode : Disable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR &= ~AT91C_VREG_PSTDBY;

    // MCK=32kHz to MCK=48MHz
    // enable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = (( (AT91C_CKGR_OSCOUNT & (0x06 <<8)) | AT91C_CKGR_MOSCEN ));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MOSCS ) );

    // enable PLL@96MHz
    AT91C_BASE_PMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x0E) |
         (AT91C_CKGR_PLLCOUNT & (28<<8)) |
         (AT91C_CKGR_MUL & (0x48<<16)));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_LOCK ) );
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1 ;
    // MCK=SLCK/2 : change prescaler first
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=PLLCK/2 : then change source
    AT91C_BASE_PMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK  ;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );

}

#elif defined (at91sam7x) || defined (at91sam7xc)
//------------------------------------------------------------------------------
/// Put the CPU in 32kHz, disable PLL, main oscillator
/// Put voltage regulator in standby mode
//------------------------------------------------------------------------------
void LowPowerMode(void)
{
    // MCK=48MHz to MCK=32kHz
    // MCK = SLCK/2 : change source first from 48 000 000 to 18. / 2 = 9M
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=SLCK : then change prescaler
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_CSS_SLOW_CLK;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // disable PLL
    AT91C_BASE_PMC->PMC_PLLR = 0;
    // Disable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = 0;

    // Voltage regulator in standby mode : Enable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR |= AT91C_VREG_PSTDBY;

    PMC_DisableProcessorClock();
}

//------------------------------------------------------------------------------
/// Put voltage regulator in normal mode
/// Return the CPU to normal speed 48MHz, enable PLL, main oscillator
//------------------------------------------------------------------------------
void NormalPowerMode(void)
{
    // Voltage regulator in normal mode : Disable VREG Low Power Mode
    AT91C_BASE_VREG->VREG_MR &= ~AT91C_VREG_PSTDBY;

    // MCK=32kHz to MCK=48MHz
    // enable Main Oscillator
    AT91C_BASE_PMC->PMC_MOR = (( (AT91C_CKGR_OSCOUNT & (0x06 <<8)) | AT91C_CKGR_MOSCEN ));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MOSCS ) );

    // enable PLL@96MHz
    AT91C_BASE_PMC->PMC_PLLR = ((AT91C_CKGR_DIV & 0x0E) |
         (AT91C_CKGR_PLLCOUNT & (28<<8)) |
         (AT91C_CKGR_MUL & (0x48<<16)));
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_LOCK ) );
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1 ;
    // MCK=SLCK/2 : change prescaler first
    AT91C_BASE_PMC->PMC_MCKR = AT91C_PMC_PRES_CLK_2;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
    // MCK=PLLCK/2 : then change source
    AT91C_BASE_PMC->PMC_MCKR |= AT91C_PMC_CSS_PLL_CLK  ;
    while( !( AT91C_BASE_PMC->PMC_SR & AT91C_PMC_MCKRDY ) );
}

#endif

//------------------------------------------------------------------------------
//         Internal functions
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// Handles interrupts coming from Timer #0.
//------------------------------------------------------------------------------
static void ISR_Timer0()
{
    unsigned char size;
    unsigned int status = AT91C_BASE_TC0->TC_SR;

    if ((status & AT91C_TC_CPCS) != 0) {
    
        // Flush PDC buffer
        size = DATABUFFERSIZE - AT91C_BASE_US0->US_RCR;
        if (size == 0) {

            AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
            return;
        }
        AT91C_BASE_US0->US_RCR = 0;
    
        // Send current buffer through the USB
        while (CDCDSerialDriver_Write(usartBuffers[usartCurrentBuffer],
                                      size, 0, 0) != USBD_STATUS_SUCCESS);
    
        // Restart read on buffer
        USART_ReadBuffer(AT91C_BASE_US0,
                         usartBuffers[usartCurrentBuffer],
                         DATABUFFERSIZE);
        usartCurrentBuffer = 1 - usartCurrentBuffer;
        AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
    }
}


//------------------------------------------------------------------------------
//         Callbacks re-implementation
//------------------------------------------------------------------------------
//------------------------------------------------------------------------------
/// Invoked when the USB device leaves the Suspended state. By default,
/// configures the LEDs.
//------------------------------------------------------------------------------
void USBDCallbacks_Resumed(void)
{
    // Initialize LEDs
    LED_Configure(USBD_LEDPOWER);
    LED_Set(USBD_LEDPOWER);
    LED_Configure(USBD_LEDUSB);
    LED_Clear(USBD_LEDUSB);
    USBState = STATE_RESUME;
}

//------------------------------------------------------------------------------
/// Invoked when the USB device gets suspended. By default, turns off all LEDs.
//------------------------------------------------------------------------------
void USBDCallbacks_Suspended(void)
{
    // Turn off LEDs
    LED_Clear(USBD_LEDPOWER);
    LED_Clear(USBD_LEDUSB);
    USBState = STATE_SUSPEND;
}


//------------------------------------------------------------------------------
/// Callback invoked when data has been received on the USB.
//------------------------------------------------------------------------------
static void UsbDataReceived(unsigned int unused,
                            unsigned char status,
                            unsigned int received,
                            unsigned int remaining)
{
    // Check that data has been received successfully
    if (status == USBD_STATUS_SUCCESS) {

        // Send data through USART
        while (!USART_WriteBuffer(AT91C_BASE_US0, usbBuffer, received));
        AT91C_BASE_US0->US_IER = AT91C_US_TXBUFE;

        // Check if bytes have been discarded
        if ((received == DATABUFFERSIZE) && (remaining > 0)) {

            TRACE_WARNING(
                      "UsbDataReceived: %u bytes discarded\n\r",
                      remaining);
        }
    }
    else {

        TRACE_WARNING( "UsbDataReceived: Transfer error\n\r");
    }
}

//------------------------------------------------------------------------------
/// Handles interrupts coming from USART #0.
//------------------------------------------------------------------------------
static void ISR_Usart0()
{
    unsigned int status = AT91C_BASE_US0->US_CSR;
    unsigned short serialState;

    // If USB device is not configured, do nothing
    if (USBD_GetState() != USBD_STATE_CONFIGURED) {

        AT91C_BASE_US0->US_IDR = 0xFFFFFFFF;
        return;
    }

    // Buffer has been read successfully
    if ((status & AT91C_US_ENDRX) != 0) {

        // Disable timer
        AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;

        // Send buffer through the USB
        while (CDCDSerialDriver_Write(usartBuffers[usartCurrentBuffer],
                                      DATABUFFERSIZE, 0, 0) != USBD_STATUS_SUCCESS);

        // Restart read on buffer
        USART_ReadBuffer(AT91C_BASE_US0,
                         usartBuffers[usartCurrentBuffer],
                         DATABUFFERSIZE);
        usartCurrentBuffer = 1 - usartCurrentBuffer;

        // Restart timer
        AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
    }

    // Buffer has been sent
    if ((status & AT91C_US_TXBUFE) != 0) {

        // Restart USB read
        CDCDSerialDriver_Read(usbBuffer,
                              DATABUFFERSIZE,
                              (TransferCallback) UsbDataReceived,
                              0);
        AT91C_BASE_US0->US_IDR = AT91C_US_TXBUFE;
    }

    // Errors
    serialState = CDCDSerialDriver_GetSerialState();

    // Overrun
    if ((status & AT91C_US_OVER) != 0) {

        TRACE_WARNING( "ISR_Usart0: Overrun\n\r");
        serialState |= CDCDSerialDriver_STATE_OVERRUN;
    }

    // Framing error
    if ((status & AT91C_US_FRAME) != 0) {

        TRACE_WARNING( "ISR_Usart0: Framing error\n\r");
        serialState |= CDCDSerialDriver_STATE_FRAMING;
    }

    CDCDSerialDriver_SetSerialState(serialState);
}

//------------------------------------------------------------------------------
//          Main
//------------------------------------------------------------------------------

//------------------------------------------------------------------------------
/// Initializes drivers and start the USB <-> Serial bridge.
//------------------------------------------------------------------------------
int main()
{
    TRACE_CONFIGURE(DBGU_STANDARD, 115200, BOARD_MCK);
    printf("-- USB Device CDC Serial Project %s --\n\r", SOFTPACK_VERSION);
    printf("-- %s\n\r", BOARD_NAME);
    printf("-- Compiled: %s %s --\n\r", __DATE__, __TIME__);

    // If they are present, configure Vbus & Wake-up pins
    PIO_InitializeInterrupts(0);

    // Configure USART
    PIO_Configure(pins, PIO_LISTSIZE(pins));
    AT91C_BASE_PMC->PMC_PCER = 1 << AT91C_ID_US0;
    AT91C_BASE_US0->US_IDR = 0xFFFFFFFF;
    USART_Configure(AT91C_BASE_US0,
                    USART_MODE_ASYNCHRONOUS,
                    115200,
                    BOARD_MCK);
    USART_SetTransmitterEnabled(AT91C_BASE_US0, 1);
    USART_SetReceiverEnabled(AT91C_BASE_US0, 1);
    AIC_ConfigureIT(AT91C_ID_US0, 0, ISR_Usart0);
    AIC_EnableIT(AT91C_ID_US0);

    // Configure timer 0
    AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_TC0);
    AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKDIS;
    AT91C_BASE_TC0->TC_IDR = 0xFFFFFFFF;
    AT91C_BASE_TC0->TC_CMR = AT91C_TC_CLKS_TIMER_DIV5_CLOCK
                             | AT91C_TC_CPCSTOP
                             | AT91C_TC_CPCDIS
                             | AT91C_TC_WAVESEL_UP_AUTO
                             | AT91C_TC_WAVE;
    AT91C_BASE_TC0->TC_RC = 0x00FF;
    AT91C_BASE_TC0->TC_IER = AT91C_TC_CPCS;
    AIC_ConfigureIT(AT91C_ID_TC0, 0, ISR_Timer0);
    AIC_EnableIT(AT91C_ID_TC0);

    // BOT driver initialization
    CDCDSerialDriver_Initialize();

    // connect if needed
    VBUS_CONFIGURE();

    // Driver loop
    while (1) {

        // Device is not configured
        if (USBD_GetState() < USBD_STATE_CONFIGURED) {

            // Connect pull-up, wait for configuration
            USBD_Connect();
            while (USBD_GetState() < USBD_STATE_CONFIGURED);

            // Start receiving data on the USART
            usartCurrentBuffer = 0;
            USART_ReadBuffer(AT91C_BASE_US0, usartBuffers[0], DATABUFFERSIZE);
            USART_ReadBuffer(AT91C_BASE_US0, usartBuffers[1], DATABUFFERSIZE);
            AT91C_BASE_US0->US_IER = AT91C_US_ENDRX
                                     | AT91C_US_FRAME
                                     | AT91C_US_OVER;
            AT91C_BASE_TC0->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;

            // Start receiving data on the USB
            CDCDSerialDriver_Read(usbBuffer,
                                  DATABUFFERSIZE,
                                  (TransferCallback) UsbDataReceived,
                                  0);
        }
        if( USBState == STATE_SUSPEND ) {
            TRACE_DEBUG("suspend  !\n\r");
            LowPowerMode();
            USBState = STATE_IDLE;
        }
        if( USBState == STATE_RESUME ) {
            // Return in normal MODE
            TRACE_DEBUG("resume !\n\r");
            NormalPowerMode();
            USBState = STATE_IDLE;
        }
    }
}