[Xenomai-help] Advice on clock sources for xenomai rtdm driver

[Xenomai-help] Advice on clock sources for xenomai rtdm driver

[Carlos Eduardo de Brito Novaes]

Hello all.

I woud like to ask you some opinion about timers.
I am slowly working on a real time driver for a acquisition board. It can be 
configured for read up to 32 anaalog channels and has a internal timer that wil 
start the conversion on a programmed time (its a 8254 timer) or the PC ca send 
a command to start conversions to. Sadly, there is no interrupt generated by 
this board, so if using the internal timer the driver has to keep polling some 
io ports to check for data and if any, retrieve it.
If I can setup a (precise) timer to trigger an interrupt, so I can start the 
conversions and on a know time read back the data. But the interrupt rate 
would be about 1K or a bit more, so RTC would not be a good idea, I think. I 
also read about HPET but it seens to have issues with xenomai and also I read 
that for some reason, some interupts would be lost. Do you guys recommend me 
something? Should I stick with polling and set up some delays with 
usleep_range or there is a good timer on PC boards and weel supported with 
xenomai?

Sorry for the long post, and tanks.

Carlos Novaes.

Re: [Xenomai-help] Advice on clock sources for xenomai rtdm driver

[Gilles Chanteperdrix]

On 07/10/2011 11:41 PM, Carlos Eduardo de Brito Novaes wrote:
> Hello all.
> 
> I woud like to ask you some opinion about timers.
> I am slowly working on a real time driver for a acquisition board. It can be 
> configured for read up to 32 anaalog channels and has a internal timer that wil 
> start the conversion on a programmed time (its a 8254 timer) or the PC ca send 
> a command to start conversions to. Sadly, there is no interrupt generated by 
> this board, so if using the internal timer the driver has to keep polling some 
> io ports to check for data and if any, retrieve it.
> If I can setup a (precise) timer to trigger an interrupt, so I can start the 
> conversions and on a know time read back the data. But the interrupt rate 
> would be about 1K or a bit more, so RTC would not be a good idea, I think. I 
> also read about HPET but it seens to have issues with xenomai and also I read 
> that for some reason, some interupts would be lost. Do you guys recommend me 
> something? Should I stick with polling and set up some delays with 
> usleep_range or there is a good timer on PC boards and weel supported with 
> xenomai?

If you are writing an rtdm driver, why not using rtdm timers?
http://www.xenomai.org/documentation/xenomai-2.5/html/api/group__rtdmtimer.html

-- 
                                                                Gilles.