ENCODER1_Position += enc_step[(pa << 3) | (pb << 2) | (a << 1) | b];
    if(ENCODER1_Position < 0) ENCODER1_Position = ENCODER1_Resolution - 1;
    else if(ENCODER1_Position == ENCODER1_Resolution) ENCODER1_Position = 0;

if (ENCODER1_Position == ENCODER1_resolution){
        ENCODER1_Position = 0;}
    if (ENCODER1_Position == -1){
        ENCODER1_Position = ENCODER1_resolution-1;}

    AT91F_AIC_ConfigureIt ( AT91C_BASE_AIC, AT91C_ID_TC0, TIMER0_INTERRUPT_LEVEL,AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL, timer0_c_irq_handler);

void timer0_c_irq_handler(void)

pAIC->AIC_SMR[AT91C_ID_TC0] = AT91C_AIC_SRCTYPE_INT_HIGH_LEVEL | TIMER0_INTERRUPT_LEVEL;
pAIC->AIC_SVR[AT91C_ID_TC0] = (unsigned long) timer0_c_irq_handler;
pAIC->AIC_IECR = (1UL << AT91C_ID_TC0);

void AT91F_TC_Open ( AT91PS_TC TC_pt, unsigned int Mode, unsigned int TimerId)
{
    unsigned int dummy;
    AT91F_PMC_EnablePeriphClock ( AT91C_BASE_PMC, 1<< TimerId );
    TC_pt->TC_CCR = AT91C_TC_CLKDIS;
    TC_pt->TC_IDR = 0xFFFFFFFF;
            dummy = TC_pt->TC_SR;
            dummy = dummy;
    TC_pt->TC_CMR = Mode;
TC_pt->TC_CMR = ((unsigned int) 0x0 << 15)    
|    AT91C_TC_CLKI
|    AT91C_TC_BURST_NONE    
|     AT91C_TC_LDBSTOP        
|    AT91C_TC_LDBDIS
|    AT91C_TC_ETRGEDG_NONE        
|    AT91C_TC_LDRA_RISING
|    AT91C_TC_LDRB_FALLING;
    
TC_pt->TC_CCR = AT91C_TC_CLKEN;
}

    dummy = TC_pt->TC_SR;
    dummy = dummy;

    TC_pt->TC_SR;

void AT91F_TC_Open ( AT91PS_TC TC_pt, unsigned int Mode, unsigned int TimerId)
{
    ...
    TC_pt->TC_CMR = Mode;

    TC_pt->TC_CMR = ((unsigned int) 0x0 << 15)    /*0 -режим захвата разрешен.*/

#define TIOA0           (1<<0)
#define TIOA1           (1<<15)
#define TIOA0_MASK      (1<<0)
#define TIOA1_MASK      (1<<15)
#define TIOA_MASK       (TIOA0_MASK|TIOA1_MASK)
…….
int main (void) {
  *AT91C_PMC_PCER =     (1UL << AT91C_ID_PIOA) |
                               (1UL << AT91C_ID_IRQ0) |  
                                (1UL << AT91C_ID_US0)  |  
                (1UL << AT91C_ID_TC1);

  pPIO->PIO_PER  = LED_MASK;
  pPIO->PIO_OER  = LED_MASK;
  pPIO->PIO_SODR = LED_MASK;

  init_timer ();
  pioa_irq_init();
  init_serial();
  timer_init ();

  while (1) {
    pPIO->PIO_CODR = LED1;
    wait(10);
    printf ("E1=%8.2f",accel_X);  
    pPIO->PIO_SODR = LED1;                       
    wait(10);  
}
}

AT91C_BASE_TC1->TC_IER  = AT91C_TC_LDRAS|AT91C_TC_LDRBS;

*AT91C_PIOA_BSR = TIOA_MASK;
*AT91C_PIOA_PDR = TIOA_MASK;

#define LED1            (1<<17)
#define LED2            (1<<18)
#define NB_LED         2
#define LED_MASK    (LED1|LED2)

#define SW1_MASK   (1<<20)
#define SW2_MASK   (1<<19)
#define SW_MASK     (SW1_MASK|SW2_MASK)      
#define SW1             (1<<20)
#define SW2             (1<<19)
  
#define TIOA0           (1<<0)
#define TIOA1           (1<<15)
#define TIOA0_MASK (1<<0)
#define TIOA1_MASK (1<<15)
#define TIOA_MASK   (TIOA0_MASK|TIOA1_MASK)    

#define ENCODER1_A_MASK        (1<<26)
#define ENCODER1_B_MASK        (1<<28)
#define ENCODER2_A_MASK        (1<<29)
#define ENCODER2_B_MASK        (1<<30)
#define ENCODER_A_MASK         (ENCODER1_A_MASK|ENCODER1_B_MASK|ENCODER2_A_MASK|ENCODER2_B_MASK)

#define ENCODER1_A             (1<<26)
#define ENCODER1_B             (1<<28)
#define ENCODER2_A             (1<<29)
#define ENCODER2_B             (1<<30)
….
/*OUTPUT*/             
    pPIO->PIO_PER   = LED_MASK;
    pPIO->PIO_OER   = LED_MASK;
    pPIO->PIO_SODR = LED_MASK;
/*INPUT*/
    pPIO->PIO_ODR  = SW_MASK;
    pPIO->PIO_PER  = SW_MASK;
    pPIO->PIO_IER  = ENCODER_A_MASK;
/*INPUT peripheral*/
    pPIO->PIO_BSR = TIOA_MASK;
    pPIO->PIO_PDR = TIOA_MASK;

const char devDescriptor[] =  {
    /* Device descriptor */
    0x12,  // bLength
    0x01,  // bDescriptorType
    0x10,  // bcdUSBL
    0x01,  //
    0x02,  // bDeviceClass:    CDC class code
    0x00,  // bDeviceSubclass: CDC class sub code
    0x00,  // bDeviceProtocol: CDC Device protocol
    0x08,  // bMaxPacketSize0
    0xFF,  // idVendorL
    0xFF,  //
    0xFF,  // idProductL
    0xFF,  //
    0x10,  // bcdDeviceL
    0x01,  //
    0x00,  // iManufacturer    // 0x01
    0x00,  // iProduct
    0x00,  // SerialNumber
    0x01  // bNumConfigs
  };

  const char cfgDescriptor[] =  {
    /* ============== CONFIGURATION 1 =========== */
    /* Configuration 1 descriptor */
    0x09,  // CbLength
    0x02,  // CbDescriptorType
    0x43,  // CwTotalLength 2 EP + Control
    0x00, 0x02,  // CbNumInterfaces
    0x01,  // CbConfigurationValue
    0x00,  // CiConfiguration
    0xC0,  // CbmAttributes 0xA0
    0x00,  // CMaxPower

    /* Communication Class Interface Descriptor Requirement */
    0x09,  // bLength
    0x04,  // bDescriptorType
    0x00,  // bInterfaceNumber
    0x00,  // bAlternateSetting
    0x01,  // bNumEndpoints
    0x02,  // bInterfaceClass
    0x02,  // bInterfaceSubclass
    0x00,  // bInterfaceProtocol
    0x00,  // iInterface

    /* Header Functional Descriptor */
    0x05,  // bFunction Length
    0x24,  // bDescriptor type: CS_INTERFACE
    0x00,  // bDescriptor subtype: Header Func Desc
    0x10,  // bcdCDC:1.1
    0x01,

    /* ACM Functional Descriptor */
    0x04,  // bFunctionLength
    0x24,  // bDescriptor Type: CS_INTERFACE
    0x02,  // bDescriptor Subtype: ACM Func Desc
    0x00,  // bmCapabilities

    /* Union Functional Descriptor */
    0x05,  // bFunctionLength
    0x24,  // bDescriptorType: CS_INTERFACE
    0x06,  // bDescriptor Subtype: Union Func Desc
    0x00,  // bMasterInterface: Communication Class Interface
    0x01,  // bSlaveInterface0: Data Class Interface

    /* Call Management Functional Descriptor */
    0x05,  // bFunctionLength
    0x24,  // bDescriptor Type: CS_INTERFACE
    0x01,  // bDescriptor Subtype: Call Management Func Desc
    0x00,  // bmCapabilities: D1 + D0
    0x01,  // bDataInterface: Data Class Interface 1

    /* Endpoint 1 descriptor */
    0x07,  // bLength
    0x05,  // bDescriptorType
    0x83,  // bEndpointAddress, Endpoint 03 - IN
    0x03,  // bmAttributes      INT
    0x0A,  // wMaxPacketSize
    0x00, 0xFF,  // bInterval

    /* Data Class Interface Descriptor Requirement */
    0x09,  // bLength
    0x04,  // bDescriptorType
    0x01,  // bInterfaceNumber
    0x00,  // bAlternateSetting
    0x02,  // bNumEndpoints
    0x0A,  // bInterfaceClass
    0x00,  // bInterfaceSubclass
    0x00,  // bInterfaceProtocol
    0x00,  // iInterface

    /* First alternate setting */
    /* Endpoint 1 descriptor */
    0x07,  // bLength
    0x05,  // bDescriptorType
    0x01,  // bEndpointAddress, Endpoint 01 - OUT
    0x02,  // bmAttributes      BULK
    AT91C_EP_OUT_SIZE,  // wMaxPacketSize
    0x00, 0x00,  // bInterval

    /* Endpoint 2 descriptor */
    0x07,  // bLength
    0x05,  // bDescriptorType
    0x82,  // bEndpointAddress, Endpoint 02 - IN
    0x02,  // bmAttributes      BULK
    AT91C_EP_IN_SIZE,  // wMaxPacketSize
    0x00, 0x00  // bInterval
  };

  const char languageIdDescriptor[] =  {
    0x04, 0x03, 0x09, 0x04
  };

  const char manufacturerDescriptor[] =  {

    10, 3, 'F', 0, 'I', 0, 'R', 0, 'M', 0
  };

  const char serialNumberDescriptor[] =  {

    10, 3, '1', 0, '2', 0, '3', 0, 'A', 0
  };

  const char nameDeviseDescriptor[] =  {

    14, 3, 'D', 0, 'E', 0, 'V', 0, 'I', 0,'C',0,'E',0
  };