gistfile1.txt

/** use DWT counter to delay */
void dwt_sleep(u32 time) 
{
	static volatile u32 *DWT_CYCCNT  = (u32 *) 0xE0001004; 
	static volatile u32 *DWT_CONTROL = (u32 *) 0xE0001000;
	static volatile u32 *SCB_DEMCR   = (u32 *) 0xE000EDFC;
	
	/* reset the counter */
 	*DWT_CYCCNT = 0;
	/* start DWT counter */
 	*DWT_CONTROL = *DWT_CONTROL | 1;
	
	/* delay */
	while(*DWT_CYCCNT <= time);

	/* stop DWT counter */
	*DWT_CONTROL = 0;
}