***
/*-----------------*/
/* LEDs Definition */
/*-----------------*/
#define AT91B_LED1            (1<<19)       // AT91C_PIO_PB19 AT91C_PB19_PWM0 AT91C_PB19_TCLK1
#define AT91B_LED2            (1<<20)       // AT91C_PIO_PB20 AT91C_PB20_PWM1 AT91C_PB20_PWM1
#define AT91B_LED3            (AT91C_PIO_PB21)       // AT91C_PIO_PB21 AT91C_PB21_PWM2 AT91C_PB21_PCK1
#define AT91B_LED4            (AT91C_PIO_PB22)       // AT91C_PIO_PB22 AT91C_PB22_PWM3 AT91C_PB22_PCK2
#define AT91B_NB_LEB          4
#define AT91B_LED_MASK        (AT91B_LED1|AT91B_LED2|AT91B_LED3|AT91B_LED4)
#define AT91D_BASE_PIO_LED       (AT91C_BASE_PIOB)

***

const int led_mask[] = { AT91B_LED1, AT91B_LED2, AT91B_LED3, AT91B_LED4 };

***
int main (void) {
  int i;

  // Enable the Clock of the PIO
  AT91C_BASE_PMC->PMC_PCER  = 1 << AT91C_ID_PIOA;
  AT91C_BASE_PMC->PMC_PCER  = 1 << AT91C_ID_PIOB;

  // Configure the PIO Lines corresponding to LED1..LED4 as Outputs
  AT91C_BASE_PIOB->PIO_PER  = AT91B_LED_MASK;
  AT91C_BASE_PIOB->PIO_OER  = AT91B_LED_MASK;

  // Clear the LED's. On the Board we must apply a "1" to turn off LEDs
  AT91C_BASE_PIOB->PIO_SODR = AT91B_LED_MASK;

  // Loop forever
  for (;;) {
    for (i = 0; i < AT91B_NB_LEB; i++) {
      AT91C_BASE_PIOB->PIO_CODR = led_mask[i];
      wait();
      AT91C_BASE_PIOB->PIO_SODR = led_mask[i];
      wait();
    }
    for (i = (AT91B_NB_LEB - 1); i >= 0; i--) {
      AT91C_BASE_PIOB->PIO_CODR = led_mask[i];
      wait();
      AT91C_BASE_PIOB->PIO_SODR = led_mask[i];
      wait();
    }
  }
}