[asterisk-dev] Change RX Signalling Bits in Dahdi drivers

[Optical Phoenix]

Hello!
Thanks very much for your input. I would very much like to create a new
signalling type,I have been intimidated by the complexity of the driver.
Would it be very difficult to create a new type?

> case DAHDI_SIG_FXSLS:
> if (!(~cursig & DAHDI_BBIT)) {      /*Dennis RINGING  */  /*<----- I think
> this is checking if the state is different from a set value? needs
> clarification*/
>  /* Check for ringing first */
> __dahdi_hooksig_pvt(chan, DAHDI_RXSIG_RING);
> break;
>  }
I added the tilde before cursig, It should now check if the signal is a "1"
correct?

and here, I have done a similar thing
}
if ((chan->sig != DAHDI_SIG_FXSLS) && (~cursig & DAHDI_BITS_ABCD)) {  /*
added tilde  Should  be true if cursig is 0000, I think?*/
    /* if went on hook */
__dahdi_hooksig_pvt(chan, DAHDI_RXSIG_ONHOOK);
} else {
__dahdi_hooksig_pvt(chan, DAHDI_RXSIG_OFFHOOK);
}

To give a little background, my goal is to create a PLAR signalling type.
Since PLAR is very simple in comparison to FXO/S and is completely
symmetrical(both sides signal the same way), It took me a while to figure
out that there were tx and rx sections because I was only familiar with
PLAR and E&M, and didn't expect there to be different cases.
ON HOOK is all ones (1111)
OFF HOOK is all zeros (0000)

Thanks again,
Dennis

On Wed, Mar 6, 2013 at 1:21 PM, Shaun Ruffell <sruffell at digium.com> wrote:

> Hi Dennis,
>
> On Wed, Mar 06, 2013 at 11:42:54AM -0500, Optical Phoenix wrote:
> > Greeting,
> > I am trying to setup PLAR signalling in asterisk. I have modified the
> FXSLS
> > TX bits in dahdi-base.c on line 2580, and I can make calls.
>
> After you get things woring, what about adding a new signalling type
> instead of modifying loopstart?
>
> > .sig_type = DAHDI_SIG_FXSLS,
> > .bits[DAHDI_TXSIG_ONHOOK]  = DAHDI_BITS_ABCD, /*changed by  for PLAR*/
> >  .bits[DAHDI_TXSIG_OFFHOOK] = (0), /*changed by  for PLAR*/
> > .bits[DAHDI_TXSIG_START]   = DAHDI_BITS_ABCD, /*changed by for PLAR*/
> >
> > When I go to change the rx, its a bit more complex. I have learned from
> > this list that dahdi_rbsbits() handles the rx bits, but my changes seem
> to
> > have no effect. Does anyone have a good understanding of this function? I
> > would appreciate any help you can provide.
> >
> > case DAHDI_SIG_FXSLS:
> > if (!(cursig & DAHDI_BBIT)) {      /*Dennis RINGING  */  /*<----- I think
> > this is checking if the state is different from a set value? needs
> > clarification*/
> >  /* Check for ringing first */
> > __dahdi_hooksig_pvt(chan, DAHDI_RXSIG_RING);
> > break;
> >  }
>
> This is just checking if new BBIT is 0, which would indicate a ring.
> At the top of dahdi_rbsbits there was already a check to see if
> cursig is different from the previously saved rxsig.
>
> > if ((chan->sig != DAHDI_SIG_FXSLS) && (cursig & DAHDI_ABIT)) {  /*<------
> > Why is it checking DAHDI_SIG_FXSLS? do I need to modify this to be 1111
> > also?*/
>
> I'm not sure about this question. When using Loop start signalling,
> the central office cannot indicate that the call was terminated to
> the remote station.  Hence, that is why the only events sent to
> __dahdi_hooksig_pvt are DAHDI_RXSIG_RING and DAHDI_RXSIG_OFFHOOK
> when configured with FSX Loop Start signalling. So basically, that
> check is to ensure that the ABIT is only looked at in FXSKS and
> FXSGS signalling (which shares this code block with the FXSLS
> signalling).
>
> >      /* if went on hook */
> > __dahdi_hooksig_pvt(chan, DAHDI_RXSIG_ONHOOK);  /*<----------I think this
> > is passing it to a function that reacts to the signal in this case the
> > onhook signal?*/
> >  } else {
> > __dahdi_hooksig_pvt(chan, DAHDI_RXSIG_OFFHOOK);  /* <------ same here but
> > with the off hook? */
> >  }
>
> Essentially, yes. dahdi_hooksig_pvt processes real state
> transitions on the line and converts them into events for Asterisk.
> For example, dahdi_rbsbits knows when a line goes offhook / onhook,
> but that could result in a WINK, FLASH, OFFHOOK, ONHOOK event to
> asterisk depending on the current state and timing of the actual
> line transitions.
>
> Hope this helps.
>
> --
> Shaun Ruffell
> Digium, Inc. | Linux Kernel Developer
> 445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
> Check us out at: www.digium.com & www.asterisk.org
>
> --
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