Re: Wait for mux to settle for PCI-DAS 1002

From: Ivan Martinez <imr_at_oersted.dtu.dk> · Date: Tue, 11 Mar 2003 13:43:21 +0100

	Hello Lorenzo,
	Thank you for the bug report. I guess adding the delay won't harm anybody, so 
we better add it and see if there any complains. Let me make the patch and 
send it to David, so I update my e-mail address too.
	Greetings,
	Ivan Martinez

On Tuesday 11 March 2003 12:47 pm, Lorenzo Dozio wrote:
> Hi,
>
> I'm working on an industrial project using RTAI-Lab with Comedi support
> to manage analog I/O of a ComputerBoards PCI-DAS 1002. I noticed that
> the driver (cb_pcidas) misses a waiting time for multiplexer to settle.
> This lack involves wrong readings with multiple consecutive
> comedi_data_read calls on different AI channels. You can test the
> outcome simply by adding other comedi_data_read to the "inp" demo under
> Comedilib.
> The right behaviour is retrieved by adding a delay of 5 us after the
> writing to the ADC Channel MUX and Control Register.
>
> --- cb_pcidas.c.orig    Tue Mar 11 12:40:52 2003
> +++ cb_pcidas.c Tue Mar 11 12:41:07 2003
> _at__at_ -815,6 +815,8 _at__at_
>                  bits |= SE;
>          outw(bits, devpriv->control_status + ADCMUX_CONT);
>
> +       udelay(5);
> +
>          /* clear fifo */
>          outw(0, devpriv->adc_fifo + ADCFIFOCLR);
>
> I don't know if this modification affects other boards supported by the
> same driver. Anyone can test it?
>
> Ciao, Lorenzo.
>
>
> _______________________________________________
> comedi mailing list
> comedi_at_comedi.org
> https://cvs.comedi.org/cgi-bin/mailman/listinfo/comedi