SparkFun Forums

[micklitz]

I'm new to pics and I'm trying out the code on the spark fun website from the Biggie area, and the pwm control software on those pages has a delay called delay_us(step) on line 125. I'm using the CC5x compiler and they delay file has no delay_us routine in it. I currently don't know how to write one. Thankyou for any ideas how to.

Here is the link:
http://www.sparkfun.com/commerce/presen ... e%20Biggie

[micklitz]

it also seems like the code is for a 4MHz clock. I'm using 20. Here is the code:
/*
DELAYS AND TIMING
=================

Delays are frequently used. There are various
ways to generate them:
1. Instruction cycle counting
2. Using the TMR0 timer
3. Watchdog timeout for low power consumption
4. Using variables achieves longer delays
*/


void delay_ms( uns16 millisec)
// Delays a multiple of 1 milliseconds at 4 MHz
// using the TMR0 timer
{
char next = 0;

OPTION = 2; // prescaler divide TMR0 rate by 8
TMR0 = 2; // deduct 2*8 fixed instruction cycles delay
do {
next += 125;
clrwdt(); // needed only if watchdog is enabled
while (TMR0 != next) // 125 * 8 = 1000 (= 1 ms)
;
} while ( -- millisec != 0);
}


void delay10( char n)
/*
Delays a multiple of 10 milliseconds using the TMR0 timer
Clock : 4 MHz => period T = 0.25 microseconds
1 IS = 1 Instruction Cycle = 1 microsecond
error: 0.16 percent
*/
{
char i;

OPTION = 7;
do {
clrwdt(); // only if watchdog enabled
i = TMR0 + 39; /* 256 microsec * 39 = 10 ms */
while ( i != TMR0)
;
} while ( --n > 0);
}


void _delay10( char x)
/*
Delays a multiple of 10 milliseconds
using instruction cycle counting
Clock : 32768 Hz => period T = 30.518 microseconds
1 Instruction Cycle = 1 IS = 4 * T = 122 microseconds
10 ms = 82 IS (81.92) => error: 0.1 percent
*/
{
do {
char i = 26; /* 2 IS */
do ; while ( --i > 0); /* 26 * 3 - 1 = 77 IS */
} while ( --x > 0); /* 3 IS */
}



char counterT;

void maintimer( void)
{
if ( TO == 1) {
/* power up or MCLR */
PORTA = 0; /* write output latch first */
TRISA = 0; /* all outputs */
TRISB = 0xFF; /* all inputs */
}
else {
/* watchdog wakeup */
if ( --counterT > 0) {
OPTION = 0x0B; /* WDT divide by 16 */
sleep(); /* waiting 16 * 18 ms =
288 ms = 0.288 seconds */
}
}

// ..

delay_ms( 5500); /* 5.5 seconds */

// ..

delay10( 100); /* 1 second */

// ..

counterT = 7; // 7 * 0.288 sec. = 2 sec. totally
OPTION = 0x0B; // 0 1011: WDT divide by 16
// main terminates by sleep();, allows low power consumption
// waiting for watchdog timeout: approx. 16*18 ms = 288 ms
}

[micklitz]

I found this on an old sparkfun website. It definately helped.

Code: Select all

/*
7/23/02
Nathan Seidle
nathan.seidle@colorado.edu
Delays for... Well, everything.
11-11 Updated the delays - now they actually delay what they say they should.
10-11-03 Updated delays. New CC5X compiler is muy optimized.
*/
//Really short delay
void delay_us(uns16 x)
{
#ifdef Clock_4MHz
//Calling with 10us returns 69us
for ( ; x > 0 ; x--);
#endif
#ifdef Clock_8MHz
//Calling with 1us returns 11us
//Calling with 10us returns 56us
//for ( ; x > 0 ; x--);
//Calling with 1us returns 7.5us
//Calling with 10us returns 48
//Calling with 1000us returns 4.5ms
while(--x);
//while(x--);
#endif
#ifdef HS_Osc
//Calling with 10us returns 13 us
//Calling with 1us returns 1.8us
while(--x) nop();
#endif
}
//General short delay
void delay_ms(uns16 x)
{
#ifdef Clock_4MHz
//Clocks out at 1002us per 1ms
int y;
for ( ; x > 0 ; x--)
for ( y = 0 ; y < 108 ; y++);
#endif
#ifdef Clock_8MHz
//Clocks out at 1006us per 1ms
uns8 y, z;
for ( ; x > 0 ; x--)
for ( y = 0 ; y < 4 ; y++)
for ( z = 0 ; z < 69 ; z++);
#endif
#ifdef HS_Osc
uns8 y, z;
//Clocks out to 1.00ms per 1ms
//9.99 ms per 10ms
for ( ; x > 0 ; x--)
for ( y = 0 ; y < 4 ; y++)
for ( z = 0 ; z < 176 ; z++);
#endif
}
43
//Delays in 31.25kHz Low Power mode using the internal 31.25kHz oscillator
void delay_s_lp(uns16 x)
{
uns16 y;
//Clocks out to 1.001s per 1s
for ( ; x > 0 ; x--)
for ( y = 0 ; y < 775 ; y++);