#define CONFIGURE_MICROSECONDS_PER_TICK

[Cláudio Silva]

Hello Luca,

The timer unit has two different stages:
The prescaler is clocked by the system clock and decremented on each
clock cycle. When the prescaler underflows, it is reloaded from the
prescaler reload register and a timer tick is generated for the two
timers and watchdog
This prescaler tick will decrement the timer count. The clock tick to
the processor will only be generated when the timer count underflows.

The value MICROSECONDS_PER_TICK will be used to program the timer
count; therefore your real clock tick interrupt will occur with a
MICROSECONDS_PER_TICK period.
(http://git.rtems.org/rtems/tree/c/src/lib/libbsp/sparc/leon2/clock/ckinit.c)

Regards,
Cláudio

On Thu, May 17, 2012 at 11:10 AM, Luca Cinquepalmi
<cinquepalmi at planetek.it> wrote:
> Hi all,
> I'm working with a leon2 processor board having:
>
> cpu clock = 16MHz
> prescaler value = 1023 (every 1024 cpu clock a tick is generated)
>
> In theory MICROSECONDS_PER_TICK should be
>
> ((cpu clock)^(-1))*1024 = 64
>
> bu it's a strange value (usually it's around 10000). Can you give me some
> explenation?
> Thank you
>
>     Luca
>
>
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