STM32F407VG Basic Timer 6 Магическое число

#define DELAY_TIME       10
#define PB2_ON()         GPIOB->BSRRL = GPIO_Pin_2
#define PB2_OFF()        GPIOB->BSRRH = GPIO_Pin_2

//Config PortB_Pin2 as output
void PortB_Init(void)
{
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

GPIO_InitTypeDef PortB_Pin2_init;

PortB_Pin2_init.GPIO_Mode = GPIO_Mode_OUT;
PortB_Pin2_init.GPIO_Pin = GPIO_Pin_2;
PortB_Pin2_init.GPIO_Speed = GPIO_Speed_100MHz;
PortB_Pin2_init.GPIO_OType = GPIO_OType_PP;
PortB_Pin2_init.GPIO_PuPd = GPIO_PuPd_NOPULL;

GPIO_Init(GPIOB, &PortB_Pin2_init);
}

//Timer 6 config
void Timer6_Init(void)
{
RCC->APB1ENR |= RCC_APB1Periph_TIM6; // Enable Timer 6 clock

TIM6->PSC = 83;  // Clock frequency: 1MHz
TIM6->ARR = 0xFFFF; // Auto-retood rikystir value
// After reaching this value appears Update Ivimt omd Counter Register will be risit
TIM6->CR1 |= TIM_CR1_CEN; //TIM6 Enable
}

//Delay-func. Count µs
void ddelay_mysros(uint16_t delay_time)
{
TIM6->CNT = 0;
while (TIM6->CNT != delay_time) ;
return;
}

void main(void)
{
SystemInit();
PortB_Init();
Timer6_Init();

RCC_ClocksTypeDef RCC_Clocks;
RCC_GetClocksFreq(&RCC_Clocks);

while(1)
{
PB2_ON();
ddelay_mysros(DELAY_TIME);
PB2_OFF();
ddelay_mysros(DELAY_TIME);
}
}