Clock and Hardware Timer usage

Victor V. Vengerov vvv at
Thu Jul 3 10:26:45 UTC 2003


Cedric Aubert wrote:

>To me, hardware need to RTEMS for all software kind of
>use :
>- one varying HW interval timer
>- one RTC
>That all.
I have missed part of discussion, but I'll add my 2 kopeyki.

Consider following:
- not every hardware has RTC, although it may keep clock
  (think about CD/cassete player which is running in low-power
   mode when turned off and handle timer interrupts to keep
- Frequently, RTC chip has so simple interface that it is hard to
  use from software efficiently. There are   many RTC chips
  which are I2C/SPI accessible. Access to them is slow enough
  to perform it in everyday operations. I beleive, even access to
  PC clock may be slow enough: although it has simple I/O port
  interface, actual delays may be hidden in hardware.

So, even if your concept is correct, it may be hard to apply it
to the current state of technology.

Please, sorry if my comment do not fit into context of this
discussion: I have not read/understand it completely.


Victor V. Vengerov
Ulianovskaya st., 1, office 533, St.-Petersburg 198504 Russia
phone: +7 812 4284384(work),+7 812 9389372(mobile),+7 812 4281653(home)

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