trunk/PIC/delay.h

/*
 *      Delay functions for HI-TECH C on the PIC18
 *
 *      Functions available:
 *              DelayUs(x)      Delay specified number of microseconds
 *              DelayMs(x)      Delay specified number of milliseconds
 *
 *      Note that there are range limits: 
 *      - on small values of x (i.e. x<10), the delay becomes less
 *      accurate. DelayUs is accurate with xtal frequencies in the
 *      range of 4-16MHZ, where x must not exceed 255. 
 *      For xtal frequencies > 16MHz the valid range for DelayUs
 *      is even smaller - hence affecting DelayMs.
 *      To use DelayUs it is only necessary to include this file.
 *      To use DelayMs you must include delay.c in your project.
 *
 *      Set the crystal frequency in the CPP predefined symbols list in
 *      HPDPIC, or on the PICC commmand line, e.g.
 *      picc -DXTAL_FREQ=4MHZ
 *
 *      or
 *      picc -DXTAL_FREQ=100KHZ
 *      
 *      Note that this is the crystal frequency, the CPU clock is
 *      divided by 4.
 *
 *      MAKE SURE this code is compiled with full optimization!!!
*/

#define MHZ     *1

#ifndef XTAL_FREQ
#define XTAL_FREQ       4MHZ            /* Crystal frequency in MHz */
#endif

#if     XTAL_FREQ < 8MHZ
#define uS_CNT  238                     /* 4x to make 1 mSec */
#endif
#if     XTAL_FREQ == 8MHZ
#ifndef uS_CNT
#define uS_CNT  244
#else
#define uS_CNT  246
#endif
#endif

#define FREQ_MULT       (XTAL_FREQ)/(4MHZ)

#define DelayUs(x)      { unsigned char _dcnt; \
                          if(x>=4) _dcnt=(x*(FREQ_MULT)/2); \
                          else _dcnt=1; \
                          while(--_dcnt > 0) \
                                {\
                                asm("nop");\
                                asm("nop");\
                                continue; }\
                } 

extern void DelayMs(unsigned char);


1	/*
2	* Delay functions for HI-TECH C on the PIC18
3	*
4	* Functions available:
5	* DelayUs(x) Delay specified number of microseconds
6	* DelayMs(x) Delay specified number of milliseconds
7	*
8	* Note that there are range limits:
9	* - on small values of x (i.e. x<10), the delay becomes less
10	* accurate. DelayUs is accurate with xtal frequencies in the
11	* range of 4-16MHZ, where x must not exceed 255.
12	* For xtal frequencies > 16MHz the valid range for DelayUs
13	* is even smaller - hence affecting DelayMs.
14	* To use DelayUs it is only necessary to include this file.
15	* To use DelayMs you must include delay.c in your project.
16	*
17	* Set the crystal frequency in the CPP predefined symbols list in
18	* HPDPIC, or on the PICC commmand line, e.g.
19	* picc -DXTAL_FREQ=4MHZ
20	*
21	* or
22	* picc -DXTAL_FREQ=100KHZ
23	*
24	* Note that this is the crystal frequency, the CPU clock is
25	* divided by 4.
26	*
27	* MAKE SURE this code is compiled with full optimization!!!
28	*/
29
30	#define MHZ *1
31
32	#ifndef XTAL_FREQ
33	#define XTAL_FREQ 4MHZ /* Crystal frequency in MHz */
34	#endif
35
36	#if XTAL_FREQ < 8MHZ
37	#define uS_CNT 238 /* 4x to make 1 mSec */
38	#endif
39	#if XTAL_FREQ == 8MHZ
40	#ifndef uS_CNT
41	#define uS_CNT 244
42	#else
43	#define uS_CNT 246
44	#endif
45	#endif
46
47	#define FREQ_MULT (XTAL_FREQ)/(4MHZ)
48
49	#define DelayUs(x) { unsigned char _dcnt; \
50	if(x>=4) _dcnt=(x*(FREQ_MULT)/2); \
51	else _dcnt=1; \
52	while(--_dcnt > 0) \
53	{\
54	asm("nop");\
55	asm("nop");\
56	continue; }\
57	}
58
59	extern void DelayMs(unsigned char);
60
61