Re: Help implementing counter

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On Tuesday 16 December 2003 10:55 am, Nils Juergens wrote:
>
> The CVS version of adv_pci1710 has one counter subdevice (which actually
> works on one of the three counters on the 8254), but the configuration
> code was rejected because it does not adhere to the comedi counter
> configuration standards (whatever those may be, if i were clearer on
> them i would have fixed the code).
>
> If you look at that code and maybe at whats in 8253.h (some stuff in
> there for 8254, too), you should be able to add support for the counter
> for your board.
>

Nils,

I think we can enable your counter configuration insn.  There are just a 
few changes that you need to make.  First, don't read the counter 
status back as data[1] in the read instruction.  The read instruction 
should read back the counter value, and thats it.  You can define another 
special configuration instruction specifically for querying the status of 
a 8253/4 counter.  Second, the option to wait (possibly forever) for the 
counter to load the value you have written to it is unacceptable.  Once 
you add the insn for querying the counter's state, the user can use that 
to poll the counter until it loads.  The config insn needs to be changed 
to use data[0] as the id number of the configuration instruction (the 
already used configuration ids are the INSN_CONFIG_* defines in 
linux/comedi.h).  Oh, and document how your configuration instruction 
works somewhere, for now it could go into 
comedi/drivers/comedi_counter_unstable.h.

- -- 
Frank

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Received on 2003-12-21Z18:56:18