proxmark3/common_arm/usb_cdc.c

//-----------------------------------------------------------------------------
// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// See LICENSE.txt for the text of the license.
//-----------------------------------------------------------------------------
// at91sam7s USB CDC device implementation
// based on the "Basic USB Example" from ATMEL (doc6123.pdf)
//-----------------------------------------------------------------------------

#include "usb_cdc.h"
#include "proxmark3_arm.h"
#include "usart_defs.h"

/*
AT91SAM7S256  USB Device Port
• Embedded 328-byte dual-port RAM for endpoints
• Four endpoints
– Endpoint 0: 8 bytes
– Endpoint 1 and 2: 64 bytes ping-pong
– Endpoint 3: 64 bytes
– Ping-pong Mode (two memory banks) for bulk endpoints
*/

//
#define AT91C_EP_CONTROL        0
#define AT91C_EP_OUT            1  // cfg bulk out
#define AT91C_EP_IN             2  // cfg bulk in
#define AT91C_EP_NOTIFY         3  // cfg cdc notification interrup

// The endpoint size is defined in usb_cdc.h

// Section: USB Descriptors
#define USB_DESCRIPTOR_DEVICE           0x01    // DescriptorType for a Device Descriptor.
#define USB_DESCRIPTOR_CONFIGURATION    0x02    // DescriptorType for a Configuration Descriptor.
#define USB_DESCRIPTOR_STRING           0x03    // DescriptorType for a String Descriptor.
#define USB_DESCRIPTOR_INTERFACE        0x04    // DescriptorType for an Interface Descriptor.
#define USB_DESCRIPTOR_ENDPOINT         0x05    // DescriptorType for an Endpoint Descriptor.
#define USB_DESCRIPTOR_DEVICE_QUALIFIER 0x06    // DescriptorType for a Device Qualifier.
#define USB_DESCRIPTOR_OTHER_SPEED      0x07    // DescriptorType for a Other Speed Configuration.
#define USB_DESCRIPTOR_INTERFACE_POWER  0x08    // DescriptorType for Interface Power.
#define USB_DESCRIPTOR_OTG              0x09    // DescriptorType for an OTG Descriptor.
#define USB_DESCRIPTOR_IAD              0x0B    // DescriptorType for a Interface Association Descriptor
#define USB_DESCRIPTOR_TYPE_BO          0x0F    // DescriptorType for a BOS Descriptor.

/* Configuration Attributes */
#define _DEFAULT    (0x01<<7)       //Default Value (Bit 7 is set)
#define _SELF       (0x01<<6)       //Self-powered (Supports if set)
#define _RWU        (0x01<<5)       //Remote Wakeup (Supports if set)
#define _HNP        (0x01 << 1)     //HNP (Supports if set)
#define _SRP        (0x01)          //SRP (Supports if set)

/* Endpoint Transfer Type */
#define _CTRL       0x00            //Control Transfer
#define _ISO        0x01            //Isochronous Transfer
#define _BULK       0x02            //Bulk Transfer
#define _INTERRUPT  0x03            //Interrupt Transfer

// (bit7 | 0 = OUT, 1 = IN)
#define _EP_IN      0x80
#define _EP_OUT     0x00
#define _EP01_OUT   0x01
#define _EP01_IN    0x81
#define _EP02_OUT   0x02
#define _EP02_IN    0x82
#define _EP03_OUT   0x03
#define _EP03_IN    0x83


/* WCID specific Request Code */
#define MS_OS_DESCRIPTOR_INDEX          0xEE
#define MS_VENDOR_CODE                  0x1C
#define MS_EXTENDED_COMPAT_ID           0x04
#define MS_EXTENDED_PROPERTIES          0x05
#define MS_WCID_GET_DESCRIPTOR          0xC0
#define MS_WCID_GET_FEATURE_DESCRIPTOR  0xC1

/* USB standard request code */
#define STD_GET_STATUS_ZERO           0x0080
#define STD_GET_STATUS_INTERFACE      0x0081
#define STD_GET_STATUS_ENDPOINT       0x0082

#define STD_CLEAR_FEATURE_ZERO        0x0100
#define STD_CLEAR_FEATURE_INTERFACE   0x0101
#define STD_CLEAR_FEATURE_ENDPOINT    0x0102

#define STD_SET_FEATURE_ZERO          0x0300
#define STD_SET_FEATURE_INTERFACE     0x0301
#define STD_SET_FEATURE_ENDPOINT      0x0302

#define STD_SET_ADDRESS               0x0500
#define STD_GET_DESCRIPTOR            0x0680
#define STD_SET_DESCRIPTOR            0x0700
#define STD_GET_CONFIGURATION         0x0880
#define STD_SET_CONFIGURATION         0x0900
#define STD_GET_INTERFACE             0x0A81
#define STD_SET_INTERFACE             0x0B01
#define STD_SYNCH_FRAME               0x0C82

/* CDC Class Specific Request Code */
#define GET_LINE_CODING               0x21A1
#define SET_LINE_CODING               0x2021
#define SET_CONTROL_LINE_STATE        0x2221

static bool isAsyncRequestFinished = false;
static AT91PS_UDP pUdp = AT91C_BASE_UDP;
static uint8_t btConfiguration = 0;
static uint8_t btConnection    = 0;
static uint8_t btReceiveBank   = AT91C_UDP_RX_DATA_BK0;

static const char devDescriptor[] = {
    /* Device descriptor */
    0x12,      // Length
    USB_DESCRIPTOR_DEVICE,      // Descriptor Type (DEVICE)
    0x00, 0x02, // Complies with USB Spec. Release (0200h = release 2.00)  0210 == release 2.10
    2,      // Device Class:    Communication Device Class
    0,      // Device Subclass: CDC class sub code ACM [ice 0x02 = win10 virtual comport ]
    0,      // Device Protocol: CDC Device protocol (unused)
    AT91C_USB_EP_CONTROL_SIZE,      // MaxPacketSize0
    0xc4, 0x9a, // Vendor ID  [0x9ac4 = J. Westhues]
    0x8f, 0x4b, // Product ID [0x4b8f = Proxmark-3 RFID Instrument]
    0x00, 0x01, // BCD Device release number (1.00)
    1,      // index Manufacturer
    2,      // index Product
    3,      // index SerialNumber
    1       // Number of Configs
};

static const char cfgDescriptor[] = {

    /* Configuration 1 descriptor */
    // -----------------------------
    9,         // Length
    USB_DESCRIPTOR_CONFIGURATION, // Descriptor Type
    (9 + 9 + 5 + 5 + 4 + 5 + 7 + 9 + 7 + 7), 0, // Total Length 2 EP + Control
    2,         // Number of Interfaces
    1,         // Index value of this Configuration (used in SetConfiguration from Host)
    0,         // Configuration string index
    _DEFAULT,      // Attributes 0xA0
    0xFA,      // Max Power consumption

    // IAD to associate the one CDC interface
    // --------------------------------------
    /*
        8,         // Length
        USB_DESCRIPTOR_IAD, // IAD_DESCRIPTOR (0x0B)
        0,         // CDC_INT_INTERFACE NUMBER  (
        2,         // IAD INTERFACE COUNT (two interfaces)
        2,         // Function Class: CDC_CLASS
        2,         // Function SubClass: ACM
        1,         // Function Protocol: v.25term
        0,         // iInterface
    */

    /* Interface 0 Descriptor */
    /* CDC Communication Class Interface Descriptor Requirement for Notification*/
    // -----------------------------------------------------------
    9,         // Length
    USB_DESCRIPTOR_INTERFACE, // Descriptor Type
    0,         // Interface Number
    0,         // Alternate Setting
    1,         // Number of Endpoints in this interface
    2,         // Interface Class code    (Communication Interface Class)
    2,         // Interface Subclass code (Abstract Control Model)
    1,         // InterfaceProtocol       (Common AT Commands, V.25term)
    0,         // iInterface

    /* Header Functional Descriptor */
    5,         // Function Length
    0x24,      // Descriptor type:    CS_INTERFACE
    0,         // Descriptor subtype: Header Functional Descriptor
    0x10, 0x01, // bcd CDC:1.1

    /* ACM Functional Descriptor */
    4,         // Function Length
    0x24,      // Descriptor Type:    CS_INTERFACE
    2,         // Descriptor Subtype: Abstract Control Management Functional Descriptor
    2,         // Capabilities        D1, Device supports the request combination of Set_Line_Coding, Set_Control_Line_State, Get_Line_Coding, and the notification Serial_State

    /* Union Functional Descriptor */
    5,         // Function Length
    0x24,      // Descriptor Type:    CS_INTERFACE
    6,         // Descriptor Subtype: Union Functional Descriptor
    0,         // MasterInterface:    Communication Class Interface
    1,         // SlaveInterface0:    Data Class Interface

    /* Call Management Functional Descriptor */
    5,         // Function Length
    0x24,      // Descriptor Type:    CS_INTERFACE
    1,         // Descriptor Subtype: Call Management Functional Descriptor
    0,         // Capabilities:       Device sends/receives call management information only over the Communication Class interface. Device does not handle call management itself
    1,         // Data Interface:     Data Class Interface

    /* Protocol Functional Descriptor */
    /*
    6,
    0x24,      // Descriptor Type: CS_INTERFACE
    0x0B,      // Descriptor Subtype: Protocol Unit functional Descriptor
    0xDD,      // constant uniq ID of unit
    0xFE,      // protocol
    */

    /* CDC Notification Endpoint descriptor */
    // ---------------------------------------
    7,                           // Length
    USB_DESCRIPTOR_ENDPOINT,     // Descriptor Type
    _EP03_IN,                    // EndpointAddress:   Endpoint 03 - IN
    _INTERRUPT,                  // Attributes
    AT91C_USB_EP_CONTROL_SIZE, 0x00, // MaxPacket Size:    EP0 - 8
    0xFF,                        // Interval polling


    /* Interface 1 Descriptor */
    /* CDC Data Class Interface 1 Descriptor Requirement */
    9,                           // Length
    USB_DESCRIPTOR_INTERFACE,    // Descriptor Type
    1,                           // Interface Number
    0,                           // Alternate Setting
    2,                           // Number of Endpoints
    0x0A,                        // Interface Class:     CDC Data interface class
    0,                           // Interface Subclass:  not used
    0,                           // Interface Protocol:  No class specific protocol required (usb spec)
    0,                           // Interface

    /* Endpoint descriptor */
    7,                           // Length
    USB_DESCRIPTOR_ENDPOINT,     // Descriptor Type
    _EP01_OUT,                   // Endpoint Address:    Endpoint 01 - OUT
    _BULK,                       // Attributes:          BULK
    AT91C_USB_EP_OUT_SIZE, 0x00,     // MaxPacket Size:      64 bytes
    0,                           // Interval:            ignored for bulk

    /* Endpoint descriptor */
    7,                           // Length
    USB_DESCRIPTOR_ENDPOINT,     // Descriptor Type
    _EP02_IN,                    // Endpoint Address:    Endpoint 02 - IN
    _BULK,                       // Attribute:           BULK
    AT91C_USB_EP_IN_SIZE, 0x00,      // MaxPacket Size:      64 bytes
    0                            // Interval:            ignored for bulk
};

// BOS descriptor
static const char bosDescriptor[] = {
    0x5,
    USB_DESCRIPTOR_TYPE_BO,
    0xC,
    0x0,
    0x1,  // 1 device capability
    0x7,
    0x10, // USB_DEVICE_CAPABITY_TYPE,
    0x2,
    0x2,  // LPM capability bit set
    0x0,
    0x0,
    0x0
};

// Microsoft OS Extended Configuration Compatible ID Descriptor
/*
static const char CompatIDFeatureDescriptor[] = {
        0x28, 0x00, 0x00, 0x00,                         // Descriptor Length 40bytes (0x28)
        0x00, 0x01,                                     // Version ('1.0')
        MS_EXTENDED_COMPAT_ID, 0x00,                    // Compatibility ID Descriptor Index  0x0004
        0x01,                                           // Number of sections. 0x1
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,       // Reserved (7bytes)
        // -----function section 1------
        0x00,                                           // Interface Number #0
        0x01,                                           // reserved (0x1)
        0x57, 0x49, 0x4E, 0x55, 0x53, 0x42, 0x00, 0x00, // Compatible ID  ('WINUSB\0\0')  (8bytes)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // Sub-Compatible ID (8byte)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00              // Reserved (6bytes)
};
*/

// Microsoft Extended Properties Feature Descriptor
/*
static const char OSprop[] = {
        // u32 Descriptor Length (10+132+64+102 == 308
        0x34, 0x01, 0, 0,
        // u16 Version ('1.0')
        0, 1,
        // u16 wIndex
        MS_EXTENDED_PROPERTIES, 0,
        // u16 wCount  -- three section
        3, 0,

        // -----property section 1------
        // u32 size  ( 14+40+78 == 132)
        132, 0, 0, 0,
        // u32 type
        1, 0, 0, 0,  // unicode string
        // u16 namelen  (20*2 = 40)
        40, 0,
        // name  DeviceInterfaceGUID
        'D',0,'e',0,'v',0,'i',0,'c',0,'e',0,'I',0,'n',0,'t',0,'e',0,'r',0,'f',0,'a',0,'c',0,'e',0,'G',0,'U',0,'I',0,'D',0,0,0,
        // u32 datalen  (39*2 = 78)
        78, 0, 0, 0,
        // data {4D36E978-E325-11CE-BFC1-08002BE10318}
        '{',0,'4',0,'d',0,'3',0,'6',0,'e',0,'9',0,'7',0,'8',0,'-',0,'e',0,'3',0,'2',0,'5',0,
        '-',0,'1',0,'1',0,'c',0,'e',0,'-',0,'b',0,'f',0,'c',0,'1',0,'-',0,'0',0,'8',0,'0',0,
        '0',0,'2',0,'b',0,'e',0,'1',0,'0',0,'3',0,'1',0,'8',0,'}',0,0,0,

        // -----property section 2------
        // u32 size  ( 14+12+38 == 64)
        64, 0, 0, 0,
        // u32 type
        1, 0, 0, 0,  // unicode string
        // u16 namelen (12)
        12, 0,
        // name Label
        'L',0,'a',0,'b',0,'e',0,'l',0,0,0,
        // u32 datalen ( 19*2 = 38 )
        38, 0, 0, 0,
        // data 'Awesome PM3 Device'
        'A',0,'w',0,'e',0,'s',0,'o',0,'m',0,'e',0,' ',0,'P',0,'M',0,'3',0,' ',0,'D',0,'e',0,'v',0,'i',0,'c',0,'e',0,0,0,

        // -----property section 3------
        // u32 size ( 14+12+76 == 102)
        102, 0, 0, 0,
        // u32 type
        2, 0, 0, 0,  //Unicode string with environment variables
        // u16 namelen (12)
        12, 0,
        // name Icons
        'I',0,'c',0,'o',0,'n',0,'s',0,0,0,
        // u32 datalen ( 38*2 ==  76)
        76, 0, 0, 0,
        // data '%SystemRoot%\\system32\\Shell32.dll,-13'
        '%',0,'S',0,'y',0,'s',0,'t',0,'e',0,'m',0,'R',0,'o',0,'o',0,'t',0,'%',0,
        '\\',0,'s',0,'y',0,'s',0,'t',0,'e',0,'m',0,'3',0,'2',0,'\\',0,
        'S',0,'h',0,'e',0,'l',0,'l',0,'3',0,'2',0,'.',0,'d',0,'l',0,'l',0,',',0,
        '-',0,'1',0,'3',0,0,0
};

*/

static const char StrLanguageCodes[] = {
    4,          // Length
    0x03,       // Type is string
    0x09, 0x04  // supported language Code 0 = 0x0409 (English)
};

// Note: ModemManager (Linux) ignores Proxmark3 devices by matching the
// manufacturer string "proxmark.org". Don't change this.
// or use the blacklisting file.
static const char StrManufacturer[] = {
    26,         // Length
    0x03,       // Type is string
    'p', 0, 'r', 0, 'o', 0, 'x', 0, 'm', 0, 'a', 0, 'r', 0, 'k', 0, '.', 0, 'o', 0, 'r', 0, 'g', 0,
};

static const char StrProduct[] = {
    20,         // Length
    0x03,       // Type is string
    'p', 0, 'r', 0, 'o', 0, 'x', 0, 'm', 0, 'a', 0, 'r', 0, 'k', 0, '3', 0
};

#ifndef WITH_FLASH
static const char StrSerialNumber[] = {
    14,         // Length
    0x03,       // Type is string
    'i', 0, 'c', 0, 'e', 0, 'm', 0, 'a', 0, 'n', 0
};
#else // WITH_FLASH is defined

// Manually calculated size of descriptor with unique ID:
// offset  0, lengt h 1: total length field
// offset  1, length  1: descriptor type field
// offset  2, length 12: 6x unicode chars (original string)
// offset 14, length  4: 2x unicode chars (underscores)      [[ to avoid descriptor being (size % 8) == 0, OS bug workaround ]]
// offset 18, length 32: 16x unicode chars (8-byte serial as hex characters)
// ============================
// total: 50 bytes
#define USB_STRING_DESCRIPTOR_SERIAL_NUMBER_LENGTH  50
char StrSerialNumber[] = {
    14,         // Length is initially identical to non-unique version ... The length updated at boot, if unique serial is available
    0x03,       // Type is string
    'i', 0, 'c', 0, 'e', 0, 'm', 0, 'a', 0, 'n', 0,
    '_', 0, '_', 0,
    'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0,
    'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0, 'x', 0,
};
void usb_update_serial(uint64_t newSerialNumber) {
    static bool configured = false; // TODO: enable by setting to false here...
    if (configured) {
        return;
    }
    // run this only once per boot... even if it fails to find serial number
    configured = true;
    // reject serial number if all-zero or all-ones
    if ((newSerialNumber == 0x0000000000000000) || (newSerialNumber == 0xFFFFFFFFFFFFFFFF)) {
        return;
    }
    // Descriptor is, effectively, initially identical to non-unique serial
    // number because it reports the shorter length in the first byte.
    // Convert uniqueID's eight bytes to 16 unicode characters in the
    // descriptor and, finally, update the descriptor's length, which
    // causes the serial number to become visible.
    for (uint8_t i = 0; i < 8; i++) {
        // order of nibbles chosen to match display order from `hw status`
        uint8_t nibble1 = (newSerialNumber >> ((8 * i) + 4)) & 0xFu; // bitmasks [0xF0, 0xF000, 0xF00000, ... 0xF000000000000000]
        uint8_t nibble2 = (newSerialNumber >> ((8 * i) + 0)) & 0xFu; // bitmasks [0x0F, 0x0F00, 0x0F0000, ... 0x0F00000000000000]
        char c1 = nibble1 < 10 ? '0' + nibble1 : 'A' + (nibble1 - 10);
        char c2 = nibble2 < 10 ? '0' + nibble2 : 'A' + (nibble2 - 10);
        StrSerialNumber[18 + (4 * i) + 0] = c1; // [ 18, 22, .., 42, 46 ]
        StrSerialNumber[18 + (4 * i) + 2] = c2; // [ 20, 24, .., 44, 48 ]
    }
    StrSerialNumber[0] = USB_STRING_DESCRIPTOR_SERIAL_NUMBER_LENGTH;
}
#endif


// size includes their own field.
static const char StrMS_OSDescriptor[] = {
    18,         // length 0x12
    0x03,       // Type is string
    'M', 0, 'S', 0, 'F', 0, 'T', 0, '1', 0, '0', 0, '0', 0, MS_VENDOR_CODE, 0
};

static const char *getStringDescriptor(uint8_t idx) {
    switch (idx) {
        case 0:
            return StrLanguageCodes;
        case 1:
            return StrManufacturer;
        case 2:
            return StrProduct;
        case 3:
            return StrSerialNumber;
        case MS_OS_DESCRIPTOR_INDEX:
            return StrMS_OSDescriptor;
        default:
            return (NULL);
    }
}

// Bitmap for all status bits in CSR which must be written as 1 to cause no effect
#define REG_NO_EFFECT_1_ALL      AT91C_UDP_RX_DATA_BK0 | AT91C_UDP_RX_DATA_BK1 \
    |AT91C_UDP_STALLSENT   | AT91C_UDP_RXSETUP \
    |AT91C_UDP_TXCOMP

// Clear flags in the UDP_CSR register and waits for synchronization
#define UDP_CLEAR_EP_FLAGS(endpoint, flags) { \
        volatile unsigned int reg; \
        reg = pUdp->UDP_CSR[(endpoint)]; \
        reg |= REG_NO_EFFECT_1_ALL; \
        reg &= ~(flags); \
        pUdp->UDP_CSR[(endpoint)] = reg; \
    }

// reset flags in the UDP_CSR register and waits for synchronization
#define UDP_SET_EP_FLAGS(endpoint, flags) { \
        volatile unsigned int reg; \
        reg = pUdp->UDP_CSR[(endpoint)]; \
        reg |= REG_NO_EFFECT_1_ALL; \
        reg |= (flags); \
        pUdp->UDP_CSR[(endpoint)] = reg; \
    }


typedef struct {
    uint32_t BitRate;
    uint8_t Format;
    uint8_t ParityType;
    uint8_t DataBits;
} AT91S_CDC_LINE_CODING, *AT91PS_CDC_LINE_CODING;

static AT91S_CDC_LINE_CODING line = { // purely informative, actual values don't matter
    USART_BAUD_RATE, // baudrate
    0,               // 1 Stop Bit
    0,               // None Parity
    8                // 8 Data bits
};

// timer counts in 21.3us increments (1024/48MHz), rounding applies
// WARNING: timer can't measure more than 1.39s (21.3us * 0xffff)
static void SpinDelayUs(int us) {
    int ticks = ((MCK / 1000000) * us + 512) >> 10;

    // Borrow a PWM unit for my real-time clock
    AT91C_BASE_PWMC->PWMC_ENA = PWM_CHANNEL(0);

    // 48 MHz / 1024 gives 46.875 kHz
    AT91C_BASE_PWMC_CH0->PWMC_CMR = PWM_CH_MODE_PRESCALER(10);      // Channel Mode Register
    AT91C_BASE_PWMC_CH0->PWMC_CDTYR = 0;                            // Channel Duty Cycle Register
    AT91C_BASE_PWMC_CH0->PWMC_CPRDR = 0xffff;                       // Channel Period Register

    uint16_t start = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;

    for (;;) {
        uint16_t now = AT91C_BASE_PWMC_CH0->PWMC_CCNTR;
        if (now == (uint16_t)(start + ticks))
            return;

        WDT_HIT();
    }
}

/*
 *----------------------------------------------------------------------------
 * \fn    usb_disable
 * \brief This function deactivates the USB device
 *----------------------------------------------------------------------------
*/
void usb_disable(void) {
    // Disconnect the USB device
    AT91C_BASE_PIOA->PIO_ODR = GPIO_USB_PU;

    // Clear all lingering interrupts
    if (pUdp->UDP_ISR & AT91C_UDP_ENDBUSRES) {
        pUdp->UDP_ICR = AT91C_UDP_ENDBUSRES;
    }
}

/*
 *----------------------------------------------------------------------------
 * \fn    usb_enable
 * \brief This function Activates the USB device
 *----------------------------------------------------------------------------
*/
void usb_enable(void) {
    // Set the PLL USB Divider
    AT91C_BASE_CKGR->CKGR_PLLR |= AT91C_CKGR_USBDIV_1 ;

    // Specific Chip USB Initialisation
    // Enables the 48MHz USB clock UDPCK and System Peripheral USB Clock
    AT91C_BASE_PMC->PMC_SCER |= AT91C_PMC_UDP;
    AT91C_BASE_PMC->PMC_PCER = (1 << AT91C_ID_UDP);

    AT91C_BASE_UDP->UDP_FADDR = 0;
    AT91C_BASE_UDP->UDP_GLBSTATE = 0;

    // Enable UDP PullUp (USB_DP_PUP) : enable & Clear of the corresponding PIO
    // Set in PIO mode and Configure in Output
    AT91C_BASE_PIOA->PIO_PER = GPIO_USB_PU; // Set in PIO mode
    AT91C_BASE_PIOA->PIO_OER = GPIO_USB_PU; // Configure as Output

    // Clear for set the Pullup resistor
    AT91C_BASE_PIOA->PIO_CODR = GPIO_USB_PU;

    // Disconnect and reconnect USB controller for 100ms
    usb_disable();

    SpinDelayUs(100 * 1000);
    // Wait for a short while
    //for (volatile size_t i=0; i<0x100000; i++) {};

    // Reconnect USB reconnect
    AT91C_BASE_PIOA->PIO_SODR = GPIO_USB_PU;
    AT91C_BASE_PIOA->PIO_OER = GPIO_USB_PU;
}

/*
 *----------------------------------------------------------------------------
 * \fn    usb_check
 * \brief Test if the device is configured and handle enumeration
 *----------------------------------------------------------------------------
*/
static int usb_reconnect = 0;
static int usb_configured = 0;
void SetUSBreconnect(int value) {
    usb_reconnect = value;
}
int GetUSBreconnect(void) {
    return usb_reconnect;
}
void SetUSBconfigured(int value) {
    usb_configured = value;
}
int GetUSBconfigured(void) {
    return usb_configured;
}

bool usb_check(void) {

    /*
    // reconnected ONCE and
    if ( !USB_ATTACHED() ){
        usb_reconnect = 1;
        return false;
    }

    // only one time after USB been disengaged and re-engaged
    if ( USB_ATTACHED() && usb_reconnect == 1 ) {

        if ( usb_configured == 0) {
            usb_disable();
            usb_enable();

            AT91F_CDC_Enumerate();

            usb_configured = 1;
            return false;
        }
    }
    */

    // interrupt status register
    AT91_REG isr = pUdp->UDP_ISR;

    // end of bus reset
    if (isr & AT91C_UDP_ENDBUSRES) {
        pUdp->UDP_ICR = AT91C_UDP_ENDBUSRES;
        // reset all endpoints
        pUdp->UDP_RSTEP  = (unsigned int) - 1;
        pUdp->UDP_RSTEP  = 0;
        // Enable the function
        pUdp->UDP_FADDR = AT91C_UDP_FEN;
        // Configure endpoint 0  (enable control endpoint)
        pUdp->UDP_CSR[AT91C_EP_CONTROL] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_CTRL);
    } else if (isr & AT91C_UDP_EPINT0) {
        pUdp->UDP_ICR = AT91C_UDP_EPINT0;
        AT91F_CDC_Enumerate();
    }
    /*
    else if (isr & AT91C_UDP_EPINT3 ) {
        pUdp->UDP_ICR = AT91C_UDP_EPINT3;
        AT91F_CDC_Enumerate();
        //pUdp->UDP_ICR |= AT91C_UDP_EPINT3;
    }
    */
    return (btConfiguration) ? true : false;
}

bool usb_poll(void) {
    if (!usb_check()) return false;
    return (pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank);
}

inline uint16_t usb_available_length(void) {
    return ((pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RXBYTECNT) >> 16);
}

/**
    In github PR #129, some users appears to get a false positive from
    usb_poll, which returns true, but the usb_read operation
    still returns 0.
    This check is basically the same as above, but also checks
    that the length available to read is non-zero, thus hopefully fixes the
    bug.
**/
bool usb_poll_validate_length(void) {
    if (!usb_check()) return false;
    if (!(pUdp->UDP_CSR[AT91C_EP_OUT] & btReceiveBank)) return false;
    return ((pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RXBYTECNT) >> 16) > 0;
}

/*
 *----------------------------------------------------------------------------
 * \fn    usb_read
 * \brief Read available data from Endpoint 1 OUT (host to device)
 *----------------------------------------------------------------------------
*/
uint32_t usb_read(uint8_t *data, size_t len) {

    if (len == 0) return 0;

    uint8_t bank = btReceiveBank;
    uint32_t packetSize, nbBytesRcv = 0;
    uint32_t time_out = 0;

    while (len)  {
        if (!usb_check())
            break;

        if (pUdp->UDP_CSR[AT91C_EP_OUT] & bank) {

            packetSize = ((pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RXBYTECNT) >> 16);
            packetSize = MIN(packetSize, len);
            len -= packetSize;
            while (packetSize--) {
                data[nbBytesRcv++] = pUdp->UDP_FDR[AT91C_EP_OUT];
            }

            // flip bank
            UDP_CLEAR_EP_FLAGS(AT91C_EP_OUT, bank)

            if (bank == AT91C_UDP_RX_DATA_BK0)
                bank = AT91C_UDP_RX_DATA_BK1;
            else
                bank = AT91C_UDP_RX_DATA_BK0;
        }

        if (time_out++ == 0x1fff)
            break;
    }

    btReceiveBank = bank;
    return nbBytesRcv;
}

static uint8_t usb_read_ng_buffer[64] = {0};
static size_t usb_read_ng_bufoff = 0;
static size_t usb_read_ng_buflen = 0;

uint32_t usb_read_ng(uint8_t *data, size_t len) {

    if (len == 0)
        return 0;

    uint8_t bank = btReceiveBank;
    uint32_t packetSize, nbBytesRcv = 0;
    uint32_t time_out = 0;

    // take first from local buffer
    if (len <= usb_read_ng_buflen) {

        for (uint32_t i = 0; i < len; i++) {
            data[nbBytesRcv++] = usb_read_ng_buffer[usb_read_ng_bufoff + i];
        }

        usb_read_ng_buflen -= len;
        if (usb_read_ng_buflen == 0)
            usb_read_ng_bufoff = 0;
        else
            usb_read_ng_bufoff += len;

        return nbBytesRcv;
    } else {
        for (uint32_t i = 0; i < usb_read_ng_buflen; i++) {
            data[nbBytesRcv++] = usb_read_ng_buffer[usb_read_ng_bufoff + i];
        }
        len -= usb_read_ng_buflen;
        usb_read_ng_buflen = 0;
        usb_read_ng_bufoff = 0;
    }

    while (len)  {
        if (!usb_check())
            break;

        if ((pUdp->UDP_CSR[AT91C_EP_OUT] & bank)) {

            uint32_t available = ((pUdp->UDP_CSR[AT91C_EP_OUT] & AT91C_UDP_RXBYTECNT) >> 16);
            packetSize = MIN(available, len);
            available -= packetSize;
            len -= packetSize;
            while (packetSize--) {
                data[nbBytesRcv++] = pUdp->UDP_FDR[AT91C_EP_OUT];
            }
            // fill the local buffer with the remaining bytes
            for (uint32_t i = 0; i < available; i++) {
                usb_read_ng_buffer[i] = pUdp->UDP_FDR[AT91C_EP_OUT];
            }
            usb_read_ng_buflen = available;
            // flip bank
            UDP_CLEAR_EP_FLAGS(AT91C_EP_OUT, bank)
            if (bank == AT91C_UDP_RX_DATA_BK0)
                bank = AT91C_UDP_RX_DATA_BK1;
            else
                bank = AT91C_UDP_RX_DATA_BK0;
        }
        if (time_out++ == 0x1fff)
            break;
    }

    btReceiveBank = bank;
    return nbBytesRcv;
}

/*
 *----------------------------------------------------------------------------
 * \fn    usb_write
 * \brief Send through endpoint 2 (device to host)
 *----------------------------------------------------------------------------
*/
int usb_write(const uint8_t *data, const size_t len) {

    if (!len) return PM3_EINVARG;
    if (!usb_check()) return PM3_EIO;

    // can we write?
    if ((pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY) != 0) return PM3_EIO;

    size_t length = len;
    uint32_t cpt = 0;


    // send first chunk
    cpt = MIN(length, AT91C_USB_EP_IN_SIZE);
    length -= cpt;
    while (cpt--) {
        pUdp->UDP_FDR[AT91C_EP_IN] = *data++;
    }

    UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
    while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY)) {};

    while (length) {
        // Send next chunk
        cpt = MIN(length, AT91C_USB_EP_IN_SIZE);
        length -= cpt;
        while (cpt--) {
            pUdp->UDP_FDR[AT91C_EP_IN] = *data++;
        }

        // Wait for previous chunk to be sent
        // (iceman) when is the bankswapping done?
        while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
            if (!usb_check()) return PM3_EIO;
        }

        UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
        while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};

        UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
        while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY)) {};
    }

    // Wait for the end of transfer
    while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
        if (!usb_check()) return PM3_EIO;
    }

    UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
    while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};


    if (len % AT91C_USB_EP_IN_SIZE == 0) {
        // like AT91F_USB_SendZlp(), in non ping-pong mode
        UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);
        while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {};

        UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
        while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};
    }

    return PM3_SUCCESS;
}

/*
 *----------------------------------------------------------------------------
 * \fn     async_usb_write_start
 * \brief  Start async write process
 * \return PM3_EIO if USB is invalid, PM3_SUCCESS if it is ready for write
 *
 * This function checks if the USB is connected, and wait until the FIFO
 * is ready to be filled.
 *
 * Warning: usb_write() should not be called between
 * async_usb_write_start() and async_usb_write_stop().
 *----------------------------------------------------------------------------
*/
int async_usb_write_start(void) {

    if (!usb_check()) return PM3_EIO;

    while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY) {
        if (!usb_check()) return PM3_EIO;
    }

    isAsyncRequestFinished = false;
    return PM3_SUCCESS;
}

/*
 *----------------------------------------------------------------------------
 * \fn    async_usb_write_pushByte
 * \brief Push one byte to the FIFO of IN endpoint (time-critical)
 *
 * This function simply push a byte to the FIFO of IN endpoint.
 * The FIFO size is AT91C_USB_EP_IN_SIZE. Make sure this function is not called
 * over AT91C_USB_EP_IN_SIZE times between each async_usb_write_requestWrite().
 *----------------------------------------------------------------------------
*/
inline void async_usb_write_pushByte(uint8_t data) {
    pUdp->UDP_FDR[AT91C_EP_IN] = data;
    isAsyncRequestFinished = false;
}

/*
 *----------------------------------------------------------------------------
 * \fn     async_usb_write_requestWrite
 * \brief  Request a write operation (time-critical)
 * \return false if the last write request is not finished, true if success
 *
 * This function requests a write operation from FIFO to the USB bus,
 * and switch the internal banks of FIFO. It doesn't wait for the end of
 * transmission from FIFO to the USB bus.
 *
 * Note: This function doesn't check if the usb is valid, as it is
 * time-critical.
 *----------------------------------------------------------------------------
*/
inline bool async_usb_write_requestWrite(void) {

    // check if last request is finished
    if (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY) {
        return false;
    }

    // clear transmission completed flag
    UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
    while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};

    // start of transmission
    UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);

    // hack: no need to wait if UDP_CSR and UDP_FDR are not used immediately.
    // while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY)) {};
    isAsyncRequestFinished = true;
    return true;
}

/*
 *----------------------------------------------------------------------------
 * \fn     async_usb_write_stop
 * \brief  Stop async write process
 * \return PM3_EIO if USB is invalid, PM3_SUCCESS if data is written
 *
 * This function makes sure the data left in the FIFO is written to the
 * USB bus.
 *
 * Warning: usb_write() should not be called between
 * async_usb_write_start() and async_usb_write_stop().
 *----------------------------------------------------------------------------
*/
int async_usb_write_stop(void) {
    // Wait for the end of transfer
    while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXPKTRDY) {
        if (!usb_check()) return PM3_EIO;
    }

    // clear transmission completed flag
    UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
    while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};

    // FIFO is not empty, request a write in non-ping-pong mode
    if (isAsyncRequestFinished == false) {
        UDP_SET_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXPKTRDY);

        while (!(pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP)) {
            if (!usb_check()) return PM3_EIO;
        }

        UDP_CLEAR_EP_FLAGS(AT91C_EP_IN, AT91C_UDP_TXCOMP);
        while (pUdp->UDP_CSR[AT91C_EP_IN] & AT91C_UDP_TXCOMP) {};
    }
    return PM3_SUCCESS;
}

/*
 *----------------------------------------------------------------------------
 * \fn    AT91F_USB_SendData
 * \brief Send Data through the control endpoint
 *----------------------------------------------------------------------------
*/
void AT91F_USB_SendData(AT91PS_UDP pudp, const char *pData, uint32_t length) {
    AT91_REG csr;

    do {
        uint32_t cpt = MIN(length, AT91C_USB_EP_CONTROL_SIZE);
        length -= cpt;

        while (cpt--)
            pudp->UDP_FDR[AT91C_EP_CONTROL] = *pData++;

        if (pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
            UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
            while (pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP);
        }

        UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXPKTRDY);

        do {
            csr = pudp->UDP_CSR[AT91C_EP_CONTROL];
            // Data IN stage has been stopped by a status OUT
            if (csr & AT91C_UDP_RX_DATA_BK0) {

                UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RX_DATA_BK0)
                return;
            }
        } while (!(csr & AT91C_UDP_TXCOMP));

    } while (length);

    if (pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {
        UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
        while (pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP);
    }
}


//*----------------------------------------------------------------------------
//* \fn    AT91F_USB_SendZlp
//* \brief Send zero length packet through the control endpoint
//*----------------------------------------------------------------------------
void AT91F_USB_SendZlp(AT91PS_UDP pudp) {
    UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXPKTRDY);
    // for non ping-pong operation, wait until the FIFO is released
    // the flag for FIFO released is AT91C_UDP_TXCOMP rather than AT91C_UDP_TXPKTRDY
    while (!(pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP)) {};
    UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_TXCOMP);
    while (pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_TXCOMP) {};
}

//*----------------------------------------------------------------------------
//* \fn    AT91F_USB_SendStall
//* \brief Stall the control endpoint
//*----------------------------------------------------------------------------
void AT91F_USB_SendStall(AT91PS_UDP pudp) {
    UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_FORCESTALL);
    while (!(pudp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_ISOERROR)) {};
    UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, (AT91C_UDP_FORCESTALL | AT91C_UDP_ISOERROR));
    while (pudp->UDP_CSR[AT91C_EP_CONTROL] & (AT91C_UDP_FORCESTALL | AT91C_UDP_ISOERROR)) {};
}

//*----------------------------------------------------------------------------
//* \fn    AT91F_CDC_Enumerate
//* \brief This function is a callback invoked when a SETUP packet is received
//* problem:
//* 1. this is for USB endpoint0.  the control endpoint.
//* 2. mixed with CDC ACM endpoint3 , interrupt, control endpoint
//*----------------------------------------------------------------------------
void AT91F_CDC_Enumerate(void) {
    uint8_t bmRequestType, bRequest;
    uint16_t wValue, wIndex, wLength, wStatus;

    if (!(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP))
        return;

    bmRequestType = pUdp->UDP_FDR[AT91C_EP_CONTROL];
    bRequest      = pUdp->UDP_FDR[AT91C_EP_CONTROL];
    wValue        = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
    wValue       |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);
    wIndex        = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
    wIndex       |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);
    wLength       = (pUdp->UDP_FDR[AT91C_EP_CONTROL] & 0xFF);
    wLength      |= (pUdp->UDP_FDR[AT91C_EP_CONTROL] << 8);

    if (bmRequestType & 0x80) {        // Data Phase Transfer Direction Device to Host
        UDP_SET_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_DIR);
        while (!(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_DIR)) {};
    }
    UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RXSETUP);
    while ((pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RXSETUP)) {};

    /*
    if ( bRequest == MS_VENDOR_CODE) {
        if ( bmRequestType == MS_WCID_GET_DESCRIPTOR ) { // C0
            if ( wIndex == MS_EXTENDED_COMPAT_ID ) {  // 4
                //AT91F_USB_SendData(pUdp, CompatIDFeatureDescriptor, MIN(sizeof(CompatIDFeatureDescriptor), wLength));
                //return;
            }
        }

        if ( bmRequestType == MS_WCID_GET_FEATURE_DESCRIPTOR ) {  //C1
            // if ( wIndex == MS_EXTENDED_PROPERTIES ) { // 5  - winusb bug with wIndex == interface index,  so I just send it always)
                //AT91F_USB_SendData(pUdp, OSprop, MIN(sizeof(OSprop), wLength));
                //return;
            // }
        }
    }
    */

    // Handle supported standard device request Cf Table 9-3 in USB specification Rev 1.1
    switch ((bRequest << 8) | bmRequestType) {
        case STD_GET_DESCRIPTOR: {

            if (wValue == 0x100)         // Return Device Descriptor
                AT91F_USB_SendData(pUdp, devDescriptor, MIN(sizeof(devDescriptor), wLength));
            else if (wValue == 0x200)    // Return Configuration Descriptor
                AT91F_USB_SendData(pUdp, cfgDescriptor, MIN(sizeof(cfgDescriptor), wLength));
            else if ((wValue & 0xF00) == 0xF00)  // Return BOS Descriptor
                AT91F_USB_SendData(pUdp, bosDescriptor, MIN(sizeof(bosDescriptor), wLength));
            else if ((wValue & 0x300) == 0x300) {  // Return String Descriptor

                const char *strDescriptor = getStringDescriptor(wValue & 0xff);
                if (strDescriptor != NULL) {
                    AT91F_USB_SendData(pUdp, strDescriptor, MIN(strDescriptor[0], wLength));
                } else {
                    AT91F_USB_SendStall(pUdp);
                }
            } else {
                AT91F_USB_SendStall(pUdp);
            }
        }
        break;
        case STD_SET_ADDRESS:
            AT91F_USB_SendZlp(pUdp);
            pUdp->UDP_FADDR = (AT91C_UDP_FEN | (wValue & 0x7F));
            pUdp->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_FADDEN : 0;
            break;
        case STD_SET_CONFIGURATION:

            /*
            *   Set or clear the device "configured" state.
            *   The LSB of wValue is the "Configuration Number". If this value is non-zero,
            *   it should be the same number as defined in the Configuration Descriptor;
            *   otherwise an error must have occurred.
            *   This device has only one configuration and its Config Number is CONF_NB (= 1).
            */
            AT91F_USB_SendZlp(pUdp);
            btConfiguration = wValue;
            pUdp->UDP_GLBSTATE  = (wValue) ? AT91C_UDP_CONFG : AT91C_UDP_FADDEN;

            // make sure we are not stalled
            /*
            UDP_CLEAR_EP_FLAGS(AT91C_EP_OUT   , AT91C_UDP_FORCESTALL);
            UDP_CLEAR_EP_FLAGS(AT91C_EP_IN    , AT91C_UDP_FORCESTALL);
            UDP_CLEAR_EP_FLAGS(AT91C_EP_NOTIFY, AT91C_UDP_FORCESTALL);
            */

            // enable endpoints
            pUdp->UDP_CSR[AT91C_EP_OUT]    = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT) : 0;
            pUdp->UDP_CSR[AT91C_EP_IN]     = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN)  : 0;
            pUdp->UDP_CSR[AT91C_EP_NOTIFY] = (wValue) ? (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN)   : 0;
            break;
        case STD_GET_CONFIGURATION:
            AT91F_USB_SendData(pUdp, (char *) & (btConfiguration), sizeof(btConfiguration));
            break;
        case STD_GET_STATUS_ZERO:
            wStatus = 0;   // Device is Bus powered, remote wakeup disabled
            AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
            break;
        case STD_GET_STATUS_INTERFACE:
            wStatus = 0;   // reserved for future use
            AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
            break;
        case STD_GET_STATUS_ENDPOINT:
            wStatus = 0;
            wIndex &= 0x0F;
            if ((pUdp->UDP_GLBSTATE & AT91C_UDP_CONFG) && (wIndex <= AT91C_EP_NOTIFY)) {
                wStatus = (pUdp->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
                AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
            } else if ((pUdp->UDP_GLBSTATE & AT91C_UDP_FADDEN) && (wIndex == AT91C_EP_CONTROL)) {
                wStatus = (pUdp->UDP_CSR[wIndex] & AT91C_UDP_EPEDS) ? 0 : 1;
                AT91F_USB_SendData(pUdp, (char *) &wStatus, sizeof(wStatus));
            } else {
                AT91F_USB_SendStall(pUdp);
            }
            break;
        case STD_SET_FEATURE_ZERO:
            AT91F_USB_SendStall(pUdp);
            break;
        case STD_SET_FEATURE_INTERFACE:
            AT91F_USB_SendZlp(pUdp);
            break;
        case STD_SET_FEATURE_ENDPOINT:
            wIndex &= 0x0F;
            if ((wValue == 0) && (wIndex >= AT91C_EP_OUT) && (wIndex <= AT91C_EP_NOTIFY)) {
                pUdp->UDP_CSR[wIndex] = 0;
                AT91F_USB_SendZlp(pUdp);
            } else {
                AT91F_USB_SendStall(pUdp);
            }
            break;
        case STD_CLEAR_FEATURE_ZERO:
            AT91F_USB_SendStall(pUdp);
            break;
        case STD_CLEAR_FEATURE_INTERFACE:
            AT91F_USB_SendZlp(pUdp);
            break;
        case STD_CLEAR_FEATURE_ENDPOINT:
            wIndex &= 0x0F;
            if ((wValue == 0) && (wIndex >= AT91C_EP_OUT) && (wIndex <= AT91C_EP_NOTIFY)) {

                if (wIndex == AT91C_EP_OUT)         pUdp->UDP_CSR[AT91C_EP_OUT] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_OUT);
                else if (wIndex == AT91C_EP_IN)     pUdp->UDP_CSR[AT91C_EP_IN] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_BULK_IN);
                else if (wIndex == AT91C_EP_NOTIFY) pUdp->UDP_CSR[AT91C_EP_NOTIFY] = (AT91C_UDP_EPEDS | AT91C_UDP_EPTYPE_INT_IN);

                AT91F_USB_SendZlp(pUdp);
            } else {
                AT91F_USB_SendStall(pUdp);
            }
            break;

        // handle CDC class requests
        case SET_LINE_CODING: {
            /*
                uint8_t i;
                for ( i = 0 ; i < 7 ; i++ )  {
                    ((uint8_t*)&line)[i] =  pUdp->UDP_FDR[AT91C_EP_CONTROL];
                }  */
            // ignore SET_LINE_CODING...
            while (!(pUdp->UDP_CSR[AT91C_EP_CONTROL] & AT91C_UDP_RX_DATA_BK0)) {};
            UDP_CLEAR_EP_FLAGS(AT91C_EP_CONTROL, AT91C_UDP_RX_DATA_BK0);
            AT91F_USB_SendZlp(pUdp);
            break;
        }
        case GET_LINE_CODING:
            AT91F_USB_SendData(pUdp, (char *) &line, MIN(sizeof(line), wLength));
            break;
        case SET_CONTROL_LINE_STATE:
            btConnection = wValue;
            AT91F_USB_SendZlp(pUdp);
            break;
        default:
            AT91F_USB_SendStall(pUdp);
            break;
    }
}