delay.c

来自「This is the source code for 5x7 Matrix d」· C语言 代码 · 共 37 行

//delay subroutines
//change the crystal frequency according to your operating frequency

#define XTAL_FREQ 20

void delay_ms(unsigned int);

#if	XTAL_FREQ >= 12

#define	delay_us(x)	{ unsigned char _dcnt; \
			  _dcnt = (x)*((XTAL_FREQ)/(12)); \
			  while(--_dcnt != 0) \
				  continue; }
#else

#define	delay_us(x)	{ unsigned char _dcnt; \
			  _dcnt = (x)/((12)/(XTAL_FREQ))|1; \
			  while(--_dcnt != 0) \
				  continue; }
#endif

void delay_ms(unsigned int cnt)
{

unsigned char	i;
	do {
		i = 4;
		do {
			delay_us(250);
		} while(--i);
	} while(--cnt);

}