How to implement microsecond delay on STM8S103F3?

e_zhui2 · ‎2010-05-03

Posted on May 04, 2010 at 03:34

jeffrey23 · ‎2011-05-17

Posted on May 17, 2011 at 15:08

How about the nop instruction approach ?

mozra272 · ‎2011-05-17

Posted on May 17, 2011 at 15:08

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Hi

Boltnut,

try this solution:

/* General Purpose 1Âµs Time base */

void Init_TIM2(void)

{

/* TimerTick = 1Âµs

Warning: fcpu must be equal to 16MHz

fck_cnt = fck_psc/presc = fcpu/16 = 1MHz --> 1 tick every 1Âµs

==> 1 Âµs / 1Âµs = 1 ticks

*/

TIM2_TimeBaseInit( TIM2_PRESCALER_16, 1);

TIM2_UpdateRequestConfig(TIM2_UPDATESOURCE_GLOBAL);

TIM2_ITConfig(TIM2_IT_UPDATE, ENABLE);

TIM2_Cmd(ENABLE);

}

/** Wait a delay

* @param[in] Delay based on timer Tick

* @return None

**/

void WaitDelay(u16 Delay)

{

GTimeStamp = 0x00;

sim();

while (GTimeStamp <= Delay);

rim();

}

/**

* @brief Timer2 Update/Overflow/Break Interruption routine.

* @par Parameters:

* None

* @retval

* None

*/

#ifdef _COSMIC_

@far @interrupt void TIM2_UPD_OVF_BRK_IRQHandler(void)

#else /* _RAISONANCE_ */

void TIM2_UPD_OVF_BRK_IRQHandler(void) interrupt 13

#endif /* _COSMIC_ */

{

GTimeStamp++;

TIM2_ClearFlag(TIM2_FLAG_UPDATE);

}

Regards

mozra

jeffrey23 · ‎2011-05-17

Posted on May 17, 2011 at 15:08

Can you explain what the sim()/rim() are in WaitDelay()

function ?

My idea is shown as below:

void I2C_Delay (u8 bTime)

{

/*

ld a,(OFST+1,sp)

72 0007 0a01 dec (OFST+1,sp)

73 0009 4d tnz a

74 000a 26f9 jrne L13

*/

bTime /= 3; // 3.5 cycles each loop !

while (bTime--)

;

} /* I2C_Delay */

bTime is in STM8S machine cycles

(SYSCLK = 1 / 16MHz = 62.5 ns = 0.0625 us) !

ne562 · ‎2011-05-17

Posted on May 17, 2011 at 15:08

#define US(us) ( F_CPU / 3000000.0 * us )

#define MS(ms) US(ms * 1000) // maximum 10ms

#define _delay( loops ) \

_asm(''$N: \n decw X \n jrne $L \n nop'', (U16)loops);

#define _delay_us(us) _delay(US(us))

void _delay_ms( U16 ms ) {

while (ms--) {

_delay_us( 1000 );

}