[asterisk-users] Questions on X100P/X101P cards

[Tzafrir Cohen]

On Thu, May 07, 2009 at 11:47:03AM +0200, Vincent wrote:
> On Thu, 7 May 2009 09:32:19 +0300, Tzafrir Cohen
> <tzafrir.cohen at xorcom.com> wrote:
> >Some X100P cards (e.g.: those that are based on SI3034, but not those
> >basedon SI3035) support "programmable" impedance settings. Sadly the
> >wcfxo driver does not support it.
> >
> >Fixing it should mostly be a matter of lifting some code from wctdm.c
> >and adapting it. Shouldn't be much of an issue. Anybody wants to try
> >that?
> >
> >(The cards I have at home are SI3035, sadly)
> >
> >A more interesting task would be to add support for some newer
> >(soft/"win"-) modems. Anybody wants to try that?
> >
> >The wcfxo driver needs some love and care. Don't expect Digium to do
> >that for you. They have more important stuff to do. Go and write your
> >own device drivers.
> 
> Thanks guys. So, provided the card has the right DAA chips to match
> the country in which it is used (FCC or CTR21), all it takes to use
> this hardware to handle a POTS line is patching Zaptel? IOW, the
> hardware itself is good enough for SOHO use?

The problem with X100P and "UK calelr ID" is, if I understand it
correctly, that the card does not detect polarity reversal.

But doesn't it provide you with the raw amperage and voltage of the
line? This should allow detecting polarity reversal. And once that is
done, the driver can send up a polarity reversal event, and no change in
Asterisk is required.

This is all within wcfxo.c and thus has no effect on the performance of
other DAHDI devices.

It sounds so simple that there must have been a good reason why
something more complicated has been required.

> 
> According to the following document, NovaVox (which no longer sells
> X100P cards) provides a Zaptel patch for cards sold by X100P.com to
> support non-FCC countries and UK CID:

Quoting later on:

| The DAA chip used in the X100P SE card is a Si3014/Si3034, which does
| support polarity reversal detection. However, because the X100P card 
| Zaptel driver does not include any polarity reversal detection code, 
| the X100P SE polarity detection feature cannot be used. An alternative 
| is to use a patch that uses a history buffer to store the CID value 
| written by Tony Hoyle. By the time the first ring arrives, the buffer 
| has a history of what was received immediately before so the CID 
| information can be extracted.

So, anybody wants to work on the code of wcfxo to add polarity
detection?

CPU is cheap (certainly so when referring to wcfxo, which will only
driver very few channels on a system), but this is still no excuse to
waste it.

Alternatively, some code to manually detect polarity reversal by
sampling amperage and voltage of the card may also help.

> 
> "This document describes how to configure an Open Source IP PBX with
> an X100P Special Edition (SE) FXO PCI card installed to support Caller
> ID received from a UK BT PSTN line. The configuration requires
> implementing a patch for Asterisk®/Zaptel that was originally written
> for the UK but has also been known to work in other countries.[...]
> 
> The Zaptel wcfxo driver has two user configurable modes of operation,
> FCC to support US line standards and CTR21 to support European line
> standards. The Silicon labs Si3012/Si3035 DAA chip used in the
> original Digium X100P card and low cost X100P clone cards only
> supports FCC mode. However, the Si3014/Si3034 DAA chip used on the
> X100P SE supports global line standards."

This is the first thing I mentioned. Should be a relatively trivial
change in the driver.

-- 
               Tzafrir Cohen
icq#16849755              jabber:tzafrir.cohen at xorcom.com
+972-50-7952406           mailto:tzafrir.cohen at xorcom.com
http://www.xorcom.com  iax:guest at local.xorcom.com/tzafrir