stm32 rtems_counter_delay_nanoseconds() longer

[Jython]

hi, the size of tick is CONFIGURE_MICROSECONDS_PER_TICK ?

On Sat, Jul 6, 2019 at 12:22 AM Gedare Bloom <gedare at rtems.org> wrote:

> On Thu, Jul 4, 2019 at 2:45 AM Jython <googcheng at gmail.com> wrote:
> >
> > is there someone could help me
> >
> I can give you some guesses.
>
> > On Sun, Jun 30, 2019 at 2:36 PM Jython <googcheng at gmail.com> wrote:
> >>
> >> a 21ms counter in fact more than 10s, see log , my rtc 10s wake up
> >>
> >> static void Delay_ms(x)
> >> {
> >>     #if 0
> ... // delete noise
> >>     #endif
> >>     volatile int i;
> >>     int us_cnt = 1000*x;
> From what you said, probably x=21, and us_cnt = 21000
>
> >>     printf("delay x %dms us_cnt %d\n", x, us_cnt);
> >>     for(i = 0; i < us_cnt; i++)
> >>         rtems_counter_delay_nanoseconds(1000);
> You make 21000 calls to this function with 1000ns (1 us) per call. You
> should debug what is happening during a call to
> rtems_counter_delay_nanoseconds(1000).
>
> Some things to be aware of. The function does not disable interrupts
> or task switches, so if you have other tasks/interrupts, they may be
> scheduled and cause your delay to be even longer than you anticipate.
>
> I would check what is the granularity of your processor ability to
> tell time. That is, what is the size of a "tick". This function will
> convert the nanosecond argument to some number of ticks, and then
> delay at least that many ticks. One possibility is that your tick is
> around 500 microseconds, so each call you make is really becoming
> rtems_counter_delay_ticks(1) ==
> rtems_counter_delay_nanoseconds(500000).  Thus, delay about .0005
> seconds per call * 21000 calls = 10.5 seconds.
>
> >>
> >>     printf("end delay\n");
> >> }
> >>
> >>
> >> [14:33:18.242]ÊÕ¡û¡ôflash_buf 32 00 00 00
> >> write page index 50
> >> log_page_no = 50
> >> before while
> >> loop begin
> >> dtr set 0
> >> baud 9600 at UART1_ChangeBaud
> >> USART_WordLength_8b
> >> USART_StopBits_1
> >> delay x 21ms us_cnt 21000
> >>
> >> [14:33:21.055]ÊÕ¡û¡ôafter clr isr 00000033
> >>
> >> [14:33:31.056]ÊÕ¡û¡ôafter clr isr 00000033
> >>
> >> [14:33:32.759]ÊÕ¡û¡ôend delay
> >> Lenggui_ClrBuffer begin okflag 0
> >>
> >>
> >>
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