On Wed, 24 Sep 2014, Joerg Wunsch wrote:
What you can do is:
#include <stdint.h>
static void
delay_us(uint8_t us)
{
while (--us != 0)
_delay_us(1);
}
To reduce the computational damage somewhat:
static void
delay_us(uint8_t us)
{
#define cyclesforus(us) \
((us)*(uint16_t)((uint64_t)(F_CPU)*0x100/1000000)/0x100)
#define kase(x) case x: \
__builtin_avr_delay_cycles(cyclesforus(x)-cyclesforus(x-1))
switch (us & 0x0F) {
kase(15); kase(14); kase(13); kase(12);
kase(11); kase(10); kase( 9); kase( 8);
kase( 7); kase( 6); kase( 5); kase( 4);
kase( 3); kase( 2); kase( 1); case 0: ;
}
if(us & 0x10) _delay_us(0x10);
if(us & 0x20) _delay_us(0x20);
if(us & 0x40) _delay_us(0x40);
if(us & 0x80) _delay_us(0x80);
}
....
delay_us(42);
delay_us(43);
While this is quite customary to do in the millisecond range
(using _delay_ms(1)), it's questionable though whether your
call and computational overhead would not rather twice the
delays in the microsecond range.
--
Michael [email protected]
"SCSI is NOT magic. There are *fundamental technical
reasons* why it is necessary to sacrifice a young
goat to your SCSI chain now and then." -- John Woods
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