Rich Adamson wrote:
<snip>
If you draw a schematic of the fxo module on the TDM card, its almost exactly like the tech note schematic for the Silicon Labs chipset.
First guess is that was the starting point for whoever built the card and modules for digium.
It appears on the surface that whoever did the design and layout is not an industry leader in professional hardware design, but there is a lot of room for opinion in that statement. Part of that stems from a missed circuit board trace on the E/F model, noisy reset line between the pci controller chip (Tigerjet) and the fxo modules, pci controller loses its ID, etc.
I've improved the stability of my card by adding a capacitor on the
reset line. Hasn't taken a hit in over two weeks.
Is this the E/F or revised H card? Where and what cap did you install?
Also, when the driver is loaded, my system reports an E/F card, but the board clearly says "H"
Anyone know for sure which is correct.
There is also major differences when comparing external gatewayAs illustrated by the problems this card has with PCI slots. Even some motherboards which clearly are PCI 2.2 can't see the card in ANY slot.
products to the TDM card, and most of those difference involve the controls inherient to dedicated microprocessors (or controllers)on the gateways, verses asterisk's approach of relying on the host processor for everything (and it's associated uncontrolled/unknown pci motherboard structure).
On top of all that, the drivers for the card (as of right now) areSOme additional problems related to the driver(s) , but probably are not of concern to most, are the way in which the driver detects pulse dialing.
the bare minimum functions needed to make the card function. The
drivers have never been extended to preload the chipset's registers
as documented in the SI tech notes.
Several of us are using Asterisk boxes as something like a private SS7 interface to interconnect electromechanical switches throughout the US.
The FXS module is configured as a ground start device to provide dial tone to an EM switch, as well as an inward path. Multiple FXS modules would allow multiple connections, and GS is normally used to prevent GLARE, or head on collisions on the outside chance that several calls in and out occur at the same time.
Digium support person #1 has stated that GS does not work on this module, and support person #2 says " it should work" In fact it does provide a GS trunk that works well for outgoing calls. On incoming calls, the module does not behave properly, in that before ringing begins, Tip should be grounded, and stay that way throughout ringing and answer. In fact, Tip seems to float somewhere during the ring cycle, and providing an external ground causes ring voltage to cease but not trip ringing.
Also dial pulse detection seems very narrow, and different dials that work fine with much other equipment is not so with this card.
That said, it seems this is one of the few FXS devices that even support pulse dial at all.
It is just another indication of the fairly weak efforts regarding this card, and it seems also for the IAXy module
If you want to play around with the card, download the pdf files from www.silabs.com for the chipset on the card. Then take a look at zaptel/fxstest.c to dump the registers to better understand how the chipset registers are loaded. You'll need to complile that code as a standalone app and run it when asterisk is not loaded.
Trying to follow the code path for a functional TDM card is not
to be taken lightly. Code is scattered across multiple drivers
and buried in asterisk modules. Even those that consider themselves
good asterisk developers stay way from this one.
That doesn't bode well for any corrections, does it.
Also, FWIW - GE branded telephones are, and have been since their introduction, JUNK!
For a quality 1,2, or 3 line POTS phone, with or without answering machine, Panasonic is the one to buy.
John Novack
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