void Delay_us(uint32_t us)
{
    uint32_t ticks = 72 * us;
    SysTick->LOAD = ticks;
    SysTick->CTRL |= 0x01;  //enable
    while (!(SysTick->CTRL&SysTick_CTRL_COUNTFLAG_Msk));
    SysTick->CTRL &= ~0x01; //disable
}

PIN_OUT_PP(One_Wire_Pin);
while (1)
{
    PIN_ON(One_Wire_Pin);
    Delay_us(500);
    PIN_OFF(One_Wire_Pin);
    Delay_us(500);
}

unsigned int One_Wire_Reset(GPIO_TypeDef * GPIOx, uint16_t PINx)
{
    unsigned int tmp;
    PIN_IN(GPIOx, PINx);
    if ((PIN_SYG(GPIOx, PINx))==0)    return One_Wire_Bus_Low_Error;

    PIN_OUT_PP(GPIOx, PINx);
    PIN_OFF(GPIOx, PINx);
    Delay_us(480);
    PIN_ON(GPIOx, PINx);
    PIN_IN(GPIOx, PINx);
    Delay_us(60);

    if ((PIN_SYG(GPIOx, PINx))==0) tmp=One_Wire_Success;
        else tmp=One_Wire_Error_No_Echo;
    Delay_us(Time_After_Reset);
    return tmp;
}

#include "systick.h"
#include "stm32f0xx.h"

void
systick_init(void)
{
SysTick->CTRL &= SysTick_CTRL_ENABLE_Msk; // stop SysTick timer
SysTick->LOAD = 0x00FFFFFF;
SysTick->VAL = 0x00FFFFFF;
SysTick->CTRL = SysTick_CTRL_ENABLE_Msk; // start SysTick timer
}

int
systick_ticks(void)
{
return SysTick->VAL;
}

int
systick_diff(int from, int to)
{
return (from - to) & 0x00FFFFFF;
}

void
systick_delay(int ticks)
{
int start = systick_ticks();
while (systick_diff(start, systick_ticks()) < ticks) ;
}

#define DWT_CYCCNT    *(volatile uint32_t *)0xE0001004
#define DWT_CONTROL   *(volatile uint32_t *)0xE0001000
#define SCB_DEMCR     *(volatile uint32_t *)0xE000EDFC
  
#ifndef HCLK
  #define   HCLK      168000000
#endif

#define dwt_ena()     (SCB_DEMCR   |=  CoreDebug_DEMCR_TRCENA_Msk)
#define dwt_dis()     (SCB_DEMCR   &= ~CoreDebug_DEMCR_TRCENA_Msk)
#define dwt_rst()     DWT_CYCCNT    = 0
#define dwt_start()   (DWT_CONTROL |= DWT_CTRL_CYCCNTENA_Msk)
#define dwt_cnt()     DWT_CYCCNT

void delay_1us (void) {
  uint32_t start, end;
  
  start = dwt_cnt();
  end = start + HCLK/1000000;
  if (end < start) while (dwt_cnt() > start);
  while (end >= dwt_cnt());
}

void delay_1ms (void) {
  uint32_t start, end;
  
  start = dwt_cnt();
  end = start + HCLK/1000;
  if (end < start) while (dwt_cnt() > start);
  while (end >= dwt_cnt());

SysTick->CTRL = 1 << 2;
u32 j = SysTick->CTRL;
SysTick->LOAD = SysTick->CURRENT = ticks;
SysTick->CTRL = 1 | 1 << 2;
while (!(SysTick->CTRL & 1 << 16));
SysTick->CTRL = 1 << 2;  //disable